1. Manuals
  2. Brands
  3. Micro crystal Manuals
  4. Power Tool
  5. RV-1805-C3
  6. Applications manual

Micro crystal RV-1805-C3 Applications Manual

Hide thumbs
Table of Contents

Advertisement

Quick Links

Download this manual
Date: November 2018
RV-1805-C3
Application Manual
Headquarters:
Micro Crystal AG
Mühlestrasse 14
CH-2540 Grenchen
Switzerland
Revision N°: 3.1
Tel.
+41 32 655 82 82
Fax
+41 32 655 82 83
Internet
www.microcrystal.com
Email
sales@microcrystal.com
1/98

Advertisement

Table of Contents
loading
Need help?

Need help?

Do you have a question about the RV-1805-C3 and is the answer not in the manual?

Questions and answers

Summary of Contents for Micro crystal RV-1805-C3

  • Page 1 RV-1805-C3 Application Manual Date: November 2018 Revision N°: 3.1 1/98 Headquarters: Micro Crystal AG Tel. +41 32 655 82 82 Mühlestrasse 14 +41 32 655 82 83 CH-2540 Grenchen Internet www.microcrystal.com Switzerland Email sales@microcrystal.com...

  • Page 2: Table Of Contents

    Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 TABLE OF CONTENTS 1. OVERVIEW ................................ 6 1.1. GENERAL DESCRIPTION ......................... 6 1.2. APPLICATIONS ............................7 2. BLOCK DIAGRAM ............................. 8 2.1. PINOUT ..............................9 2.2. PIN DESCRIPTION ..........................10 2.3.
  • Page 3 Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 4.7. GENERATING HUNDREDTHS OF A SECOND ..................46 4.8. WATCHDOG TIMER ..........................46 4.9. DIGITAL CALIBRATION .......................... 47 4.9.1. XT OSCILLATOR DIGITAL CALIBRATION ..................47 4.9.2. RC OSCILLATOR DIGITAL CALIBRATION ..................48 4.10.
  • Page 4 Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 4.16. SOFTWARE RESET ..........................65 4.17. SLEEP CONTROL STATE MACHINE ....................65 4.17.1. RUN STATE ............................66 4.17.2. SWAIT STATE (SLEEP_WAIT STATE) .................... 66 4.17.3. SLEEP STATE ..........................66 4.17.4.
  • Page 5 RST AC ELECTRICAL CHARACTERISTICS ..................91 7. APPLICATION INFORMATION ........................92 7.1. OPERATING RV-1805-C3 ........................92 7.2. OPERATING RV-1805-C3 WITH BACKUP BATTERY/SUPERCAP ............. 93 8. RECOMMENDED REFLOW TEMPERATURE (LEADFREE SOLDERING) ..........94 9. PACKAGE ................................ 95 9.1. DIMENSIONS AND SOLDERPADS LAYOUT ..................95 9.2.

  • Page 6: Overview

    The power requirement is significantly lower than any other industry RTC (as low as 17 nA). The RV-1805-C3 includes an on-chip oscillator to provide a minimum power consumption, full RTC functions including battery backup and programmable counters and alarms for timer and watchdog functions, and either an I C serial interface for communication with a host controller.

  • Page 7: Applications

    Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 1.2. APPLICATIONS The RV-1805-C3 RTC module has been specially designed for ultimate low power consumption:  60 nA with crystal oscillator (at 3V)  22 nA with RC oscillator and Autocalibration (ACP = 512 sec. at 3V) ...

  • Page 8: Block Diagram

    Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 2. BLOCK DIAGRAM Hundredths Analog Seconds Compare Minutes Hours BACKUP Date Power Months Control Years Weekdays Hundredths Alarm Seconds Alarm Minutes Alarm Hours Alarm Date Alarm Months Alarm...

  • Page 9: Pinout

    Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 2.1. PINOUT RV-1805-C3 Package: Cap_RC CLK/INT BACKUP 1805 9/98...

  • Page 10: Pin Description

    CLKS field (see CONFIGURATION REGISTERS, 11h - Control2). is also asserted low on a power up until the RV-1805-C3 has exited the reset state and is accessible via the I interface. can drive the static value of the CLKB bit.

  • Page 11: Functional Description

    2.3. FUNCTIONAL DESCRIPTION The RV-1805-C3 is an extreme low power CMOS Real-Time Clock / Calendar module with built-in “Tuning-Fork” crystal with the nominal frequency of 32.768 kHz and an on-chip auto-calibrated RC-oscillator; no external components are required for the oscillator circuitry.

  • Page 12: Register Organization

    These bits are not described in the sections below. All of the GPx bits are cleared when the RV-1805-C3 powers up, and they can therefore be used to allow software to determine if a true Power On Reset (POR) has occurred or hold other initialization data.
  • Page 13 Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 Register Definitions (10h to FFh): Address Function Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Control1 STOP 12/24 PSWB CLKB...

  • Page 14: Time And Date Registers

    Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 3.2. TIME AND DATE REGISTERS 00h - Hundredths This register holds the count of hundredths of seconds, in two binary coded decimal (BCD) digits. Values will be from 00 to 99. Note that in order to divide from 32.768 kHz, the hundredths register will not be fully accurate at all times but will be correct every 500 ms.
  • Page 15 Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 03h - Hours This register holds the count of hours, in two binary coded decimal (BCD) digits. Values will be from 00 to 23 if the 12/24 bit (see CONFIGURATION REGISTERS, 10h - Control1) is clear. If the 12/24 bit is set, the AM/PM bit will be 0 for AM hours and 1 for PM hours, and hour values will range from 1 to 12.
  • Page 16 Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 05h - Months This register holds the current month, in two binary coded decimal (BCD) digits. Values will range from 01 to 12. Address Function Bit 7 Bit 6...

  • Page 17: Alarm Registers

    Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 3.3. ALARM REGISTERS 08h - Hundredths Alarm This register holds the alarm value for hundredths of seconds, in two binary coded decimal (BCD) digits. Values will range from 00 to 99. It holds the special values FFh and (F0h to F9h) when ARPT bit is 7. See TIMER REGISTERS, 18h - Countdown Timer Control.
  • Page 18 Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 0Bh - Hours Alarm This register holds the alarm value for hours, in two binary coded decimal (BCD) digits. Values will range from 00 to 23 if the 12/24 bit (see CONFIGURATION REGISTERS, 10h - Control1) is clear. If the 12/24 bit is set, the AM/PM bit will be 0 for AM hours and 1 for PM hours, and hour values will be from 1 to 12.
  • Page 19 Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 0Dh - Months Alarm This register holds the alarm value for months, in two binary coded decimal (BCD) digits. Values will range from 01 to 12. Address Function...

  • Page 20: Configuration Registers

    Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 3.4. CONFIGURATION REGISTERS 0Fh – Status This register holds a variety of status bits. The register may be written at any time to clear or set any status flag. If the ARST bit is set (see 10h - Control1), any read of the Status Register will clear interrupt flags in this register (WDF, BLF, TF, AF and EVF).
  • Page 21 The PSW pin is a normal open drain output. PSWC The PSW pin is driven by an approximately 1 Ω pull-down which allows the RV-1805-C3 to switch power to other system devices through this pin. Write RTC Prevents inadvertent software access to the Counters.
  • Page 22 Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 11h - Control2 This register holds additional control and configuration signals for the flexible output pins and PSW. Note that PSW and are open drain outputs. Address Function...
  • Page 23 This controls the duration of the Inverse AIRQ interrupt as shown below. The interrupt output always goes high when the corresponding flag in the Status Register is cleared. In order to minimize current drawn by the RV-1805-C3 this field should be kept at 3h. Level (static) for both XT mode and RC mode.
  • Page 24 Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 13h – Square Wave SQW This register holds the control for the square wave signal SQW. Note that some frequency selections are not valid if the RC Oscillator is selected.

  • Page 25: Calibration Registers

    Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 3.5. CALIBRATION REGISTERS 14h - Calibration XT This register holds the control signals for the digital calibration function of the XT Oscillator. This register is initialized with a factory value which calibrates the XT Oscillator. The highest modified frequency is 16.384 kHz (see XT OSCILLATOR DIGITAL CALIBRATION).
  • Page 26 Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 15h - Calibration RC Upper This register holds the control signals for the fine digital calibration function of the low power RC Oscillator. This register is initialized with a factory value which calibrates the RC Oscillator. The highest modified frequency is 64 Hz (see RC OSCILLATOR DIGITAL CALIBRATION).

  • Page 27: Sleep Control Register

    Unused, but has to be 0 to avoid extraneous leakage. Sleep Flag No previous SLEEP state occurred. Flag is set when the RV-1805-C3 enters Sleep Mode. This allows software to determine if a SLEEP has occurred since the last time this bit was read. Sleep Wait periods.

  • Page 28: Timer Registers

    Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 3.7. TIMER REGISTERS 18h - Countdown Timer Control This register controls the Countdown Timer function. Note that the TFS = 00 frequency selection is slightly different depending on whether the 32.768 kHz XT Oscillator or the RC Oscillator is selected. In some RC Oscillator modes, the interrupt pulse output is specified as RC Pulse.
  • Page 29 Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 Table 2: Countdown Timer Function Select TRPT Interrupt signal Countdown Timer Frequency Interrupt Pulse Width Pulse/ Single/ XT Oscillator RC Oscillator XT Oscillator RC Oscillator Level Repeat Pulse...
  • Page 30 Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 1Bh - Watchdog Timer This register controls the Watchdog Timer function. Address Function Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0...

  • Page 31: Oscillator Registers

    PSWS field to a value of 6. This insures that a powered down I C master (i.e., the host controller) does not corrupt the RV-1805-C3. XT Oscillator Failure Interrupt Enable OFIE Disables the XT oscillator failure interrupt.

  • Page 32: Miscellaneous Registers

    Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 1Dh – Oscillator Status Register This register holds several miscellaneous bits used to control and observe the oscillators. Address Function Bit 7 Bit 6 Bit 5 Bit 4...

  • Page 33: Analog Control Registers

    Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 3.10. ANALOG CONTROL REGISTERS 20h - Trickle Charge This register controls the Trickle Charger. The Configuration Key CONFKEY must be written with the value 9Dh in order to enable access to this register. See TRICKLE CHARGER.
  • Page 34 Description C in VBACKUP Power state The I C interface is disabled in the VBACKUP Power state in order to prevent erroneous accesses to the RV-1805-C3 if the bus master loses IOBM power. The RV-1805-C3 will not disable the I...

  • Page 35: Id Registers

    Mode. 3.11. ID REGISTERS 28h – ID0 - Part Number Upper Register (Read Only) This register holds the upper eight bits of the part number in BCD format, which is always 18h for the RV-1805-C3. Address Function Bit 7 Bit 6...
  • Page 36 This register holds part of the manufacturing information of the part, including bit 9 of the manufacturing lot number and the upper 7 bits of the unique part identifier. The 15-bit ID field contains a unique value for each RV-1805-C3 part.

  • Page 37: Ram Registers

    Value Description Unused, but must be set to 0 to avoid extraneous leakage. If 0, an internal output is completely disconnected when the RV-1805-C3 is powered from BACKUP BLF Polarity The Battery Low flag BLF is set when the V...
  • Page 38 Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 40h - 7Fh – Standard RAM 64 bytes of RAM space. The data in the RAM is held when using battery power. The upper 2 bits of the effective memory RAM address are taken from the XADS field, and the lower 6 bits are taken from the address offset, supporting a total RAM of 256 bytes.

  • Page 39: Register Reset Values Summary

    Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 3.13. REGISTER RESET VALUES SUMMARY Address Function Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Hundredths Seconds Minutes Hours Date...

  • Page 40: Detailed Functional Description

    (e.g., pushbutton signals), the generation of clock outputs, and watchdog timer functionality. 3. Power management features built into the RV-1805-C3 enable it to operate as a backup device in both line-powered and battery-powered systems. An integrated power control module automatically detects...

  • Page 41: I 2 C Interface

    Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 4.2. C INTERFACE The I C interface is for bidirectional, two-line communication between different ICs or modules. The device is accessed at addresses D2h/D3h, and supports Fast Mode (up to 400 kHz). The I C interface consists of two lines: one bi-directional data line (SDA) and one clock line (SCL).

  • Page 42: Data Valid

    C bus is the Master; the devices which are controlled by the Master are the Slaves. A device generating a message is a Transmitter; a device receiving a message is the Receiver. The RV-1805-C3 acts as a Slave-Receiver or Slave-Transmitter.

  • Page 43: Addressing

    = 0) or a read (R/ = 1) operation (results in D2h or D3h) and the RV-1805-C3 supplies the ACK. The RV-1805-C3 ignores all other address values and does not respond with an ACK. In the write operation, a data transfer is terminated by sending either the STOP condition or the START condition of the next data transfer.

  • Page 44: Write Operation

    After reading or writing one byte, the Register Address is automatically incremented by 1. 1) Master sends out the START condition. 2) Master sends out Slave Address, D2h for the RV-1805-C3; the R/ bit is a 0 indicating a write operation. 3) Acknowledgement from the RV-1805-C3.

  • Page 45: Read Operation

    RC OSCILLATOR The RV-1805-C3 includes an extremely low power RC oscillator which runs at typically 122 Hz (Fnom = 128 Hz). This oscillator is selected by setting the OSEL bit to 1. Switching between the XT and RC Oscillators is guaranteed to produce less than one second of error in the Calendar Counters.

  • Page 46: Hundredths Synchronization

    4.8. WATCHDOG TIMER The RV-1805-C3 includes a Watchdog Timer, which can be configured to generate an interrupt or a reset if it times out. The Watchdog Timer is controlled by the Watchdog Timer Register (see TIMER REGISTERS, 1Bh - Watchdog Timer).

  • Page 47: Digital Calibration

    Timer and Watchdog Timer clocks and the clock driven onto the pin. In addition to the normal calibration, the RV-1805-C3 also includes an Extended Calibration field to compensate a higher XT oscillator frequency. The frequency generated by the Crystal Oscillator may be reduced by -122 ppm multiplied by the value in the XTCAL (see OSCILLATOR REGISTERS, 1Dh –...

  • Page 48: Rc Oscillator Digital Calibration

    64 Hz or lower caused by calibration will be no more than one 64 Hz period. This maximum jitter applies to all clocks in the RV-1805-C3, including the Calendar Counter, Countdown Timer and Watchdog Timer clocks and the clock driven onto the pins.
  • Page 49 Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 The following figure shows the modified clock at the 64 Hz level with the achieved average time accuracy in ppm at 96 seconds (arbitrary). The average calculation was started at the time t = 0 seconds (T = 25°C and V...

  • Page 50: Autocalibration

    4.10. AUTOCALIBRATION The RV-1805-C3 includes the capability of using the internal RC Oscillator for all timing functions. For increased accuracy at a small power penalty, the RC Oscillator may be periodically calibrated to the digitally calibrated Crystal (XT) Oscillator which is turned on only during this calibration. The overall process is referred to as Autocalibration and under most conditions produces a clock with long term accuracy essentially indistinguishable from the digitally calibrated XT Oscillator alone, as shown in the RC/Acal bubble in the following Figure.

  • Page 51: Xt Autocalibration Mode

    RC Oscillator as close to the digitally calibrated XT Oscillator as possible. In RC Autocalibration Mode, the OSEL register bit is set to 1, ACAL is set to 10 or 11 and the RV-1805-C3 uses the RC Oscillator at all times.

  • Page 52: Cap_Rc Pin

    RC Autocalibration Mode is typically the most useful mode, because it allows a dramatic reduction in the power used by the RV-1805-C3 while maintaining the accuracy of the internal clock. The RC is always used as the internal clock so that no time deviations occur as can be seen with XT Autocalibration Mode and automatic switchover.
  • Page 53 Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 Autocalibration maintains the RC Oscillator at a frequency very close to the digitally calibrated XT Oscillator, but there are obviously small deviations which can occur on each cycle. However, as temperature and the raw RC Oscillator frequency vary, deviations typically cancel each other out and produce very low accumulated deviation.
  • Page 54 Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 Autocalibration Time Deviation relative to the digitally calibrated XT Oscillator, ACP = 512 seconds: ACP = 512 Seconds -40 to 85 -25 to 75 -10 to 60 10 to 40 Average Temperature Change Rate in °C/min.

  • Page 55: A Real World Example

    Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 The deviations in both of the cases above for relatively low temperature change rates are less than the deviation introduced by the XT Oscillator itself. The following Figure shows the raw XT deviation, which is more strongly a function of the maximum temperature range than the calibrated RC deviation.

  • Page 56: Rc Autocalibration Timing Accuracy Example

    Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 4.11.9. RC AUTOCALIBRATION TIMING ACCURACY EXAMPLE The RC Oscillator displays relatively high internal jitter caused by pulse addition or subtraction of the Autocalibration process as well as the inherent thermal noise jitter of the RC Oscillator itself. This jitter introduces significant time accuracy errors for short time periods.

  • Page 57: Power Analysis

    XT Oscillator must be used. If such a clock is required only occasionally, the RV-1805-C3 may be temporarily placed in XT Mode by setting the OSEL bit to 0, and then returned to RC Mode by setting OSEL back to 1 when the high frequency clock is no longer required.

  • Page 58: Xt Oscillator Failure Detection

    OF flag will generate an interrupt OFIRQ. If the FOS bit is set and the RV-1805-C3 is currently using the XT Oscillator, it will automatically switch to the RC Oscillator on an XT Oscillator Failure. This guarantees that the system clock will not stop in any case. The OMODE bit indicates the currently selected oscillator, which will not match the oscillator requested by the OSEL bit if the XT Oscillator is not running.

  • Page 59: Alarm Interrupt Airq

    4.13.2. ALARM INTERRUPT AIRQ The RV-1805-C3 may be configured to generate the AIRQ interrupt when the values in the Time and Date Registers match the values in the Alarm Registers. Which register comparisons are required to generate AIRQ is controlled by the ARPT field as described in TIMER REGISTERS, 18h - Countdown Timer Control, allowing software to specify the interrupt interval.

  • Page 60: Servicing Interrupts

    The following Figure illustrates the various power states and the transitions between them. There are three power states: 1. POR – the power on reset state. If the RV-1805-C3 is in this state, all registers including the Counter Registers are initialized to their reset values.

  • Page 61: Automatic Switchover Summary

    . If the XT oscillator is selected and the BOS bit is set (see OSCILLATOR REGISTERS, 1Ch - Oscillator BACKUP Control), the RV-1805-C3 will automatically switch to the RC oscillator in the VBACKUP Power state in order to conserve battery power (Autocalibration Mode according to the ACAL field). If the IOBM bit is clear (see ANALOG CONTROL REGISTERS, 27h –...

  • Page 62: Analog Comparator

    PIN CONTROL AND LEAKAGE MANAGEMENT (POWER CONTROL) Like most ICs, the RV-1805-C3 may draw unnecessary leakage current if an input pin floats to a value near the threshold or an output pin is pulled to a power supply. Because external devices may be powered from V...

  • Page 63: Power Up Timing

    RESET SUMMARY The RV-1805-C3 controls the RST output in a variety of ways, as shown in the following Table. The assertion of RST is a low signal if the RSTP bit is 0, and the assertion is high if RSTP is 1. RSTP always powers up as a zero so that on power RST is always asserted low.

  • Page 64: Power Up Reset

    RV-1805-C3 4.15.1. POWER UP RESET When the RV-1805-C3 powers up (see POWER UP TIMING) and RST will be asserted low until I accesses are enabled. At that point will go high, and RST will continue to be asserted low for the delay , and will then be deasserted to high.

  • Page 65: Sleep

    4.15.3. SLEEP If the SLRST bit is set, RST will be asserted low whenever the RV-1805-C3 is in Sleep Mode (see SLEEP CONTROL). Once a trigger is received and the RV-1805-C3 exits Sleep Mode, RST will continue to be asserted low for the t delay.

  • Page 66: Run State

    RUN STATE RUN is the normal operating state of the RV-1805-C3. PSW is 0, RST is 1, SLP is 0, and SLF flag holds the state of the previous Sleep. The SLF flag should be cleared by software before entering the SWAIT state.
  • Page 67 Number of ~8 ms waiting periods STOP bit: Stops clocking system SLF bit: Flag is set when the RV-1805-C3 enters SLEEP state. Can be cleared by software. TF bit: Countdown Timer Flag. Set when timer reaches zero. Outputs RST pin...

  • Page 68: Slp Protection

    4.17.4. SLP PROTECTION Since going into Sleep Mode may prevent an MCU from accessing the RV-1805-C3, it is critical to insure that the RV-1805-C3 can receive an interrupt signal (combined interrupt signal IRQ). To guarantee this, the SLP signal cannot be set unless the STOP bit is 0 and at least one of the following interrupt functions are enabled (sets the internal status signal VAL to 1): 1.

  • Page 69: System Power Control Applications

    Under normal circumstances, the PSW pin is pulled to V receives full power. The MCU initiates a sleep operation by setting SLP to 1, and when the RV-1805-C3 enters the SLEEP state the PSW pin is opened and power is completely removed from the MCU. This results in significant additional power savings relative to the other alternatives because even very low power MCUs require more current in their lowest power state than the RV-1805-C3.

  • Page 70: Vdd Power Switched

    The following Figure illustrates the application in which the RV-1805-C3 communicates with the system MCU using the reset function. In this case the MCU sets the SLRST bit so that when the RV-1805-C3 enters the SLEEP state, it brings RST low to reset the MCU, and initiates a sleep operation. When the trigger occurs, the RV-1805-C3 releases the MCU from reset, and may also generate an interrupt which the MCU can query to determine how reset was exited.

  • Page 71: Interrupt Driven

    WAKE The key value of the RV-1805-C3 in this type of system is the ability to put the MCU into an off state, and providing a very rich variety of triggers which can cause the RV-1805-C3 to wake the MCU from the off state. There are a number of different triggers which may be useful.

  • Page 72: Alarms

    ERRORS Any failure interrupt in the RV-1805-C3 may also be configured to wake the MCU. This can be particularly valuable for an XT Oscillator Failure detection, when software may need to respond to the error in order to report the problem quickly.

  • Page 73: Saving Parameters

    POWER SWITCH ELECTRICAL CHARACTERISTICS The power switch on the RV-1805-C3 PSW pin has a typical on resistance of 1 Ω over the full temperature range so that currents up to 50 mA may be handled without appreciable voltage drop. This allows the RV-1805-C3 to switch power to multiple devices in most systems, which can be particularly important for components without internal Sleep functions.

  • Page 74: Managing Mcu Active Power

    One example of this is fingerprint recognition, which is rarely accessed but must provide very fast response with complex processing. The RV-1805-C3 power management functions enable a system design where the processor is powered down the vast majority of the time, providing low average power combined with very high instantaneous performance.

  • Page 75: Digital Architecture Summary

    Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 5. DIGITAL ARCHITECTURE SUMMARY The following Figure illustrates the overall architecture of the pin inputs and outputs of the RV-1805-C3. Digital Architecture Summary: TIRQ Countdown Timer CLKB SQWS...

  • Page 76: Electrical Specifications

    Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 6. ELECTRICAL SPECIFICATIONS 6.1. ABSOLUTE MAXIMUM RATINGS The following Table lists the absolute maximum ratings. Absolute Maximum Ratings: SYMBOL PARAMETER TEST UNIT Power Supply Voltage -0.3 Backup Supply Voltage -0.3...
  • Page 77 DDSWR DDSWF must be higher than V by at least this voltage to insure the RV-1805-C3 remains in the VBACKUP Power state. BACKUP Maximum V falling slew rate to guarantee correct switchover to VBACKUP Power state. There is no V falling slew rate requirement if switching to the VBACKUP power source is not required.

  • Page 78: Operating Parameters

    (+/-12%) for autocalibration mode. When this happens, an autocalibration failure will occur and the ACF interrupt flag is set. The RV-1805-C3 should be switched to use the XT oscillator as its clock source when this occurs. Please see the AUTOCALIBRATION FAILURE section for more details.
  • Page 79 Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 The following Figure shows the typical calibrated RC oscillator frequency variation vs. temperature. The RC oscillator is factory calibrated at 2.8V, 25°C (OFFSETR = Preconfigured reset value). Factory Calibrated RC Oscillator, Typical Frequency Variation vs. Temperature (64 Hz level is modified): 72.5...

  • Page 80: Xt Frequency Characteristics

    Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 6.5. XT FREQUENCY CHARACTERISTICS For this Table, T = -40 °C to 85 °C unless otherwise indicated. V = 1.7 to 3.6V, TYP values at 25 °C and 3.0V, = 32.768 kHz.

  • Page 81: Vdd Supply Current

    Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 6.6. SUPPLY CURRENT The following Table lists the current supplied into the V power input under various conditions. For this table, T -40 °C to 85 °C, V = 0 V to 3.6 V, TYP values at 25 °C, VDD Power state.
  • Page 82 Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 The following Figure shows the typical VDD power state operating current vs. temperature in RC mode. Typical V Current vs. Temperature in RC Mode: = 3.0V = 1.8V Temperature (°C)
  • Page 83 Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 The following Figure shows the typical VDD power state operating current vs. voltage for XT Oscillator and RC Oscillator modes and the average current in RC Autocalibrated mode with ACP = 512 seconds.
  • Page 84 Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 The following Figure shows the typical additional VDD power state operating current with a 32.768 kHz clock output on the pin. Test conditions: T = 25 °C. All inputs and outputs except are at 0 V or V .

  • Page 85: Vbackup Supply Current

    Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 6.7. SUPPLY CURRENT BACKUP The following Table lists the current supplied into the V power input under various conditions. For this table, BACKUP = -40 °C to 85 °C, TYP values at 25 °C, MAX values at 85 °C, VBACKUP Power state.
  • Page 86 Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 The following Figure shows the typical VBACKUP power state operating current vs. temperature in RC mode. Typical V Current vs. Temperature in RC Mode: BACKUP = 3.0V BACKUP = 1.8V...
  • Page 87 Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 The following Figure shows the typical VBACKUP power state operating current vs. voltage for XT Oscillator and RC Oscillator modes and the average current in RC Autocalibrated mode with ACP = 512 seconds, V = 0 V.

  • Page 88: Bref Electrical Characteristics

    Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 6.8. BREF ELECTRICAL CHARACTERISTICS The following Table lists the parameters of the V voltage thresholds. BREF values other than those listed in BACKUP the table are not supported. For this table, T = -20 °C to 70 °C, TYP values at 25 °C, V...

  • Page 89: I 2 C Ac Electrical Characteristics

    Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 6.9. C AC ELECTRICAL CHARACTERISTICS The following Figure and Table describe the I C AC electrical parameters. C AC Parameter Definitions: HD:DAT SU:DAT HD:STA HIGH RISE FALL SU:STO...

  • Page 90: Power On Ac Electrical Characteristics

    Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 6.10. POWER ON AC ELECTRICAL CHARACTERISTICS The following Figure and Table describe the power on AC electrical characteristics for the pin and XT oscillator. Power On AC Electrical Characteristics:...

  • Page 91: Rst Ac Electrical Characteristics

    Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 6.11. AC ELECTRICAL CHARACTERISTICS The following Figure and Table describe the RST AC electrical characteristics. RST AC Parameter Characteristics: LOW:VDD DDRST DDST VH:NRST VL:NRST For the following Table, T = -40 °C to 85 °C, V...

  • Page 92: Application Information

    Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 7. APPLICATION INFORMATION 7.1. OPERATING RV-1805-C3 10 nF RV-1805-C3 RESET BACKUP Cap_RC 47 pF A 10 nF decoupling capacitor is recommended close to the device. , RST and interface lines SCL, SDA are open drain and require pull-up resistors to V offers selectable frequencies 32.768 kHz to 1/60 Hz for application use.

  • Page 93: Operating Rv-1805-C3 With Backup Battery/Supercap

    Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 7.2. OPERATING RV-1805-C3 WITH BACKUP BATTERY/SUPERCAP 1.5 kΩ 10 nF 10 nF Main Battery Backup Battery/ BACKUP Supercap RV-1805-C3 RESET Cap_RC 47 pF pin. The optimal value is 1.5 kΩ,...

  • Page 94: Recommended Reflow Temperature (Leadfree Soldering)

    Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 8. RECOMMENDED REFLOW TEMPERATURE (LEADFREE SOLDERING) Maximum Reflow Conditions in accordance with IPC/JEDEC J-STD-020C “Pb-free” Critical Zone to T Ramp-up Tsmax Tsmin Ramp-down Preheat t 25°C to Peak...

  • Page 95: Package

    Metal lid is connected to V (pin #6) Tolerances: unless otherwise specified ± 0.1mm Drawing: RV-1805-C3_Pack-drw_20181025 All dimensions in mm typical. 9.2. MARKING AND PIN #1 INDEX Laser marking RV-1805-C3 Package: (top view) Product Date Code M843A1 1805 Part Designation Pin 1 Index 95/98...

  • Page 96: 10. Packing & Shipping Information

    Micro Crystal Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3 10. PACKING & SHIPPING INFORMATION Reel: 7” = 178 mm Ø 13 min. 12.4 max. 17 Carrier Tape: Material: Polycarbonate, conductive Width: 12 mm Tape Leader and Trailer: Minimum length 300 mm ±0,1...

  • Page 97: Handling Precautions For Crystals Or Modules With Embedded Crystals

    Shock and vibration: Keep the crystal / module from being exposed to excessive mechanical shock and vibration. Micro Crystal guarantees that the crystal / module will bear a mechanical shock of 5000g / 0.3 ms. The following special situations may generate either shock or vibration: Multiple PCB panels - Usually at the end of the pick &...

  • Page 98: 12. Document Revision History

    November 2018 Removed Automotive, 1.2. Information furnished is believed to be accurate and reliable. However, Micro Crystal assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use...

Table of Contents