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Features
■
Buck-boost dc/dc converter
■
Drives one power white LED up to 800 mA from
2.7 V to 5.5 V in QFN
■
Drives one power white LED up to 800 mA from
3.3 V to 5.5 V in BGA
■
Efficient up to 92%
■
Output current control
■
1.8 MHz typ. fixed frequency PWM
■
Synchronous rectification
■
Full I²C control
■
Operational modes:
– Shutdown mode
– Shutdown + NTC
– Ready mode + auxiliary red LED
– Flash mode: up to 800 mA
– Torch mode: up to 200 mA
■
Soft and hard triggering of flash
■
Flash and torch dimming with 16 exponential
values
■
Dimmable red LED indicator auxiliary output
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Internally or externally timed flash operation
■
Digitally programmable safety time-out in flash
mode
■
LED overtemperature detection and protection
with external NTC resistor
■
Opened and shorted LED failure detection and
protection
■
Chip over temperature detection and protection
■
< 1 µA shutdown current
Table 1.
Device summary
Order code
STCF03PNR
STCF03TBR
1. Available on request.
September 2008
High power white LED driver with I²C interface
(1)
TFBGA25 (3x3 mm)
QFN20 (4x4)
■
Packages:
– QFN20 (4x4)
– TFBGA25 (3x3)
Applications
■
Cell phone and smart phone
■
Camera flashes/strobe
■
PDAs and digital still cameras
Description
The STCF03 is a high efficiency power supply
solution to drive a single flash LED in camera
phone, PDAs and other hand-held devices. It is a
buck - boost converter to guarantee a proper LED
current control over all possible conditions of
battery voltage and output voltage; the output
current control ensure a good current regulation
over the forward voltage spread characteristics of
the flash LED.
Thanks to the high efficiency of the converter
allows having the input current taken from the
battery remain under 1.5 A. (See
(continued))
Package
QFN20 (4x4 mm)
Rev 5
STCF03
TFBGA25 (3x3)
1: Description
Packaging
4500 parts per reel
3000 parts per reel
www.st.com
1/35
35
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Related Manuals for ST QFN20
Summary of Contents for ST QFN20
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Page 1: Table 1. Device Summary
TFBGA25 (3x3) ■ Output current control ■ 1.8 MHz typ. fixed frequency PWM ■ Packages: ■ Synchronous rectification – QFN20 (4x4) ■ Full I²C control – TFBGA25 (3x3) ■ Operational modes: Applications – Shutdown mode – Shutdown + NTC ■... -
Page 2: Table Of Contents
Contents STCF03 Contents Description (continued) ........6 Diagram . - Page 3 Contents STCF03 TCH_ON ..........20 NTC_ON .
- Page 4 List of tables STCF03 List of tables Table 1. Device summary ............1 Table 2.
- Page 5 List of figures STCF03 List of figures Figure 1. Block diagram ............7 Figure 2.
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Page 6: Description (Continued)
Description (continued) STCF03 Description (continued) All the functions of the device are controlled through the I²C which helps bus that allows to reduce logic pins on the package and to save PCB tracks on the board. Hard and soft- triggering of flash are both supported. The device includes many functions to protect the chip and the power LED such as: a soft start control, chip over temperature detection and protection as well as opened and shorted LED detection and protection. -
Page 7: Diagram
Diagram STCF03 Diagram Figure 1. Block diagram 7/35... -
Page 8: Pin Configuration
Pin configuration STCF03 Pin configuration Figure 2. Pin connections (bottom view) QFN20 (3x3) TFBGA25 (3x3) Table 2. Pin description Pin n° for Pin n° for Symbol Name and function QFN20 TFBGA25 E1, D2 VLX2 Inductor connection Rx resistor connection NTC resistor connection... -
Page 9: Maximum Ratings
1. Power dissipation is related parameter to used PCB. The recommended PCB design is included in the application note. Note: Absolute maximum ratings are those values beyond which damage to the device may occur. Functional operation under these condition is not implied. Table 4. Thermal data Symbol Parameter QFN20 TFBGA25 Unit Thermal resistance junction-ambient °C/W thJA 9/35... -
Page 10: Application
Application STCF03 Application Figure 3. Application schematic **: Connect to V , or GND or SDA or SCL to choose one of the 4 different I²C Slave Addresses. ***: Optional components to support auxiliary functions. Table 5. List of external components Component Manufacturer Part number... -
Page 11: Electrical Characteristics
Electrical characteristics STCF03 Electrical characteristics Table 6. Electrical characteristics = 0.27 Ω R = 1.8 Ω, R = 25°C, V = 3.6 V, 2xC = 10 µF, C = 1 µF, L = 4.7 µH, R 15 kΩ, Typ. values @25°C, unless otherwise specified). Symbol Parameter Test condition... - Page 12 Electrical characteristics STCF03 Table 6. Electrical characteristics (continued) = 0.27 Ω R = 1.8 Ω, R = 25°C, V = 3.6 V, 2xC = 10 µF, C = 1 µF, L = 4.7 µH, R 15 kΩ, Typ. values @25°C, unless otherwise specified). Symbol Parameter Test condition...
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Page 13: Introduction
Introduction STCF03 Introduction The STCF03 is a buck-boost converter, dedicated to power and control the current of a power white LED in a camera cell phone. The device operates at a constant switching frequency of 1.8 MHz typ. It provides an output voltage down to 2.5 V and up to 5.3 V, from a 2.7 V to 5.5 V supply voltage. -
Page 14: Add Pin
Introduction STCF03 7.2.4 ADD pin With this pin it is possible to select one of the 4 possible I²C slave addresses. No internal pull-up nor pull-down is provided. The pin has to be connected either GND, V , SCL or SDA to select the desired I²C slave address (see Table Table 7. -
Page 15: I²C Bus Interface
Introduction STCF03 I²C bus interface Data transmission from the main µP STCF03 and vice versa takes place through the 2 wires I²C bus interface wires, consisting of the two lines SDA and SCL (pull-up resistors to a positive supply voltage must be externally connected). The recommended maximum voltage of these signals should be 3.0 V. -
Page 16: Byte Format
Introduction STCF03 Byte format Every byte transferred to the SDA line must contain 8 bits. Each byte must be followed by an acknowledge bit. The MSB is transferred first. One data bit is transferred during each clock pulse. The data on the SDA line must remain stable during the HIGH period of the clock pulse. -
Page 17: Writing To A Single Register
Introduction STCF03 Table 8. Interface protocol Device address + R/W bit Register address Data Writing to a single register Writing to a single register starts with a START bit followed by the 7 bit device address of STCF03. The 8 bit is the R/W bit, which is 0 in this case. -
Page 18: Writing To Multiple Registers With Incremental Addressing
Introduction STCF03 The register address byte determines the first register in which the read or write operation takes place. When the read or write operation is finished, the register address is automatically increased. 7.10 Writing to multiple registers with incremental addressing It would be unpractical to send several times the device address and the address of the register when writing to multiple registers. -
Page 19: Reading From Multiple Registers With Incremental Addressing
Introduction STCF03 Figure 11. Reading from a single register DEVICE DEVICE ADDRESS ADDRESS DEVICE DEVICE ADDRESS ADDRESS ADDRESS ADDRESS DATA DATA 7 bits 7 bits REGISTER REGISTER 7 bits 7 bits SDA LINE SDA LINE 7.12 Reading from multiple registers with incremental addressing Reading from multiple registers starts in the same way like reading from a single register. -
Page 20: Description Of Internal Registers
Description of internal registers STCF03 Description of internal registers Table 9. I²C register mapping function Register name SUB ADDRESS (hex) Operation CMD_REG R / W DIM_REG R / W AUX_REG R / W STAT_REG R only Table 10. Command register CMD_REG (write mode) SUB ADD=00... -
Page 21: Ftim_0~3
Description of internal registers STCF03 FTIM_0~3 This 4bit register defines the maximum flash duration. It is intended to limit the energy dissipated by the LED to a maximum safe value or to leave to the STCF03 the control of the flash duration during normal operation. -
Page 22: Auxi_0~3
Description of internal registers STCF03 Table 12. Auxiliary register AUX_REG (write mode) SUB ADD=02 AUXI_3 AUXI_2 AUXI_1 AUXI_0 AUXT_3 AUXT_2 AUXT_1 AUXT_0 Power ON, SHUTDOWN MODE RESET Value AUXI_0~3 This 4 bits register defines the AUX LED current from 0 to 20 mA. See AUX LED dimming table for reference. -
Page 23: F_Run
Description of internal registers STCF03 Table 15. Status register STAT_REG (read mode) SUB ADD=03 F_RUN LED_F NTC_W NTC_H OT_F VOUTOK_N Power ON, SHUTDOWN MODE RESET Value 8.10 F_RUN This bit is kept HIGH by the STCF03 during flash mode. By checking this bit, the µP can verify if the flash mode is running or has been terminated by the time counter. -
Page 24: Voutok_N
Description of internal registers STCF03 8.15 VOUTOK_N This bit is set by the STCF03. It is used to protect the device, if the output is shorted. The VOUTOK_N bit is set to HIGH at the start-up. Then a current generator of 20 mA charges the output capacitor for 360 µs typ. -
Page 25: Detailed Description
Detailed description STCF03 Detailed description PowerON reset This mode is initiated by applying a supply voltage above the V threshold PW_ON RESET value. An internal timing (~1 µs) defines the duration of this status. The logic blocks are powered, but the device doesn't respond to any input. The registers are reset to their default values, the ATN and SDA pins are in high-Z, and the I²C slave address is internally set by reading the ADD pin configuration. -
Page 26: External (Μp) Temporization Using Trig_En Bit
Detailed description STCF03 TRIG_EN bit, and also resets the F_RUN bit. The ATN pin is pulled down to inform the µP that the STAT_REG has been updated. External (µP) temporization using TRIG_EN bit Even if it is possible, it is not recommended to use the TRIG_EN bit to start and stop the flash operation, because of I²C bus latencies: this would result in inaccurate flash timing. -
Page 27: Typical Performance Characteristics
Typical performance characteristics STCF03 Typical performance characteristics Figure 15. Efficiency Figure 16. I vs T_DIMM OTORCH Efficiency of the application at Io=800mA Efficiency of the application at Io=800mA Efficiency of the application at Io=55mA Efficiency of the application at Io=55mA = 2.7V = 2.7V = 3.6V... -
Page 28: Figure 21. I Q Vs Temp. V I = 5.5 V Ready-Mode
Typical performance characteristics STCF03 Figure 21. I vs Temp. V = 5.5 V ready-mode Figure 22. Start-up in flash mode 800 mA at = 3.6 V TRIG I_IN -40°C -40°C 25°C 25°C 85°C 85°C Temp. Temp. Figure 23. Line transient in flash mode 800 mA, change of V from 2.7 V to 3.3 V in 10 µs... -
Page 29: Package Mechanical Data
JEDEC Standard JESD97. The maximum ratings related to soldering conditions are also marked on the inner box label. ECOPACK is an ST trademark. ECOPACK specifications are available at: www.st.com... - Page 30 Package mechanical data STCF03 QFN20 (4mm x 4mm) mechanical data mils. Dim. Min. Typ. Max. Min. Typ. Max. 0.80 0.90 1.00 31.5 35.4 39.4 0.02 0.05 0.65 1.00 25.6 39.4 0.20 0.18 0.25 0.30 11.8 3.85 4.00 4.15 151.6 157.5 163.4...
- Page 31 Package mechanical data STCF03 TFBGA25 mechanical data mils. Dim. Min. Typ. Max. Min. Typ. Max. 1.16 39.4 43.3 45.7 0.25 0.78 0.86 30.7 33.9 0.25 0.30 0.35 11.8 13.8 114.2 118.1 122.0 78.8 114.2 118.1 122.0 78.8 19.7 0.25 7539979/A 31/35...
- Page 32 Package mechanical data STCF03 Tape & reel QFNxx/DFNxx (4x4) mechanical data inch. Dim. Min. Typ. Max. Min. Typ. Max. 12.992 12.8 13.2 0.504 0.519 20.2 0.795 3.898 3.976 14.4 0.567 4.35 0.171 4.35 0.171 0.043 0.157 0.315 32/35...
- Page 33 Package mechanical data STCF03 Tape & reel TFBGA25 mechanical data inch. Dim. Min. Typ. Max. Min. Typ. Max. 12.992 12.8 13.2 0.504 0.519 20.2 0.795 2.362 14.4 0.567 0.130 0.130 1.60 0.063 0.153 0.161 0.311 0.319 33/35...
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Page 34: Revision History
Revision history STCF03 Revision history Table 17. Document revision history Date Revision Changes 30-Jan-2007 First Release. 27-Mar-2007 The OVP min. value on table 5 is changed: 5.5 V ==> 5.3 V. 28-Aug-2007 Modified Table 12-Sep-2007 Modified Figure 10-Sep-2008 Added Figure 4 on page 34/35... - Page 35 No license, express or implied, by estoppel or otherwise, to any intellectual property rights is granted under this document. If any part of this document refers to any third party products or services it shall not be deemed a license grant by ST for the use of such third party products or services, or any intellectual property contained therein or considered as a warranty covering the use in any manner whatsoever of such third party products or services or any intellectual property contained therein.
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