Analog Devices LINEAR LTM 8005 Manual
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Analog Devices LINEAR LTM 8005 Manual

38vin boost ymodule regulator for led drive with 10a switch
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FEATURES
Wide Input Voltage Range: 5V to 38V
n
Supports Boost or SEPIC Power Topologies
n
Adjustable LED Current Up to 1.6A
n
40V 10A Internal Power Switch
n
Wide Temperature Range: –40°C to 150°C
n
Input and Output Current Reporting
n
Internal Switch for PWM and Output Disconnect
n
Internal Spread Spectrum Frequency Modulation
n
3000:1 True Color PWM™ Dimming
n
Open LED Protection with OPENLED Flag
n
Short-Circuit Protection and SHORTLED Flag
n
Soft-Start with Programmable Fault Restart Timer
n
9mm × 11.25mm × 2.22mm BGA
n
APPLICATIONS
High Power LED, High Voltage LED
n
Accurate Current-Limited Voltage Regulators
n
TYPICAL APPLICATION
350mA at 30.5V to 35.5V LED String from 6V to 27V V
V
IN
6V TO 27V
C
IN
2×
4.7µF
50V
L: COILCRAFT XAL7030-822ME
C
, C
: MURATA GRM31CR71H475KA12
IN
OUT
PIN NOT USED IN THIS CIRCUIT: IVINCOMP
Document Feedback
38V
IN
1M
V
IVINP
IVINN
IN
EN/UVLO
93.1k
OVLO
19.1k
PWM
V
REF
CTRL1
100k
CTRL2
18.7k
SS
VC
RT
4.7k
23.2k
0.1µF
f = 350kHz
10nF
For more information
Boost µModule Regulator for
LED Drive with 10A Switch
DESCRIPTION
The
LTM
8005
is a 38V
®
micromodule) LED driver designed to regulate current or
voltage and is ideal for driving LEDs. The fixed frequency
and current mode architecture result in stable operation
over a wide range of supply and output voltages. Spread
spectrum frequency modulation (SSFM) can be activated
for improved electromagnetic compatibility (EMC) perfor-
mance. The ground-referred voltage FB pin serves as the
input for several LED protection features, and also allows the
converter to operate as a constant voltage source. The PWM
input provides LED dimming ratios of up to 3000:1, and the
CTRL inputs provide additional analog dimming capability.
The low profile package enables utilization of unused
space on the bottom of PC boards. The LTM8005 is pack-
aged in thermally enhanced, compact over-molded Ball
Grid Array (BGA) package suitable for automated assem-
bly by standard surface mount equipment. The LTM8005
is RoHS compliant.
All registered trademarks and trademarks are the property of their respective owners.
(Boost) with Spread Spectrum
IN
L
8.2µH
SW
DA
V
OUT
ISN
LTM8005
LED
AUX
FB
ISMON
GND OPENLED SHORTLED
RAMP
www.analog.com
LTM8005
, 38V
boost µModule (power
IN
OUT
C
OUT
2×
4.7µF
50V
374k
LED
12.4k
STRING
0.1µF
6.8nF
8005 TA01a
Rev. B
1

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Summary of Contents for Analog Devices LINEAR LTM 8005

  • Page 1 LTM8005 Boost µModule Regulator for LED Drive with 10A Switch FEATURES DESCRIPTION Wide Input Voltage Range: 5V to 38V 8005 is a 38V , 38V boost µModule (power ® Supports Boost or SEPIC Power Topologies micromodule) LED driver designed to regulate current or Adjustable LED Current Up to 1.6A voltage and is ideal for driving LEDs.

  • Page 2: Absolute Maximum Ratings

    LTM8005 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Note 1) TOP VIEW , EN/UVLO, IVINN, IVINP ........50V ISN Above LED ............40V SW, ISN, LED, V , VOUT-DA ........40V CTRL1, CTRL2 ………………........15V BANK 4 V BANK 5 BANK 6 PWM, SHORTLED, OPENLED ........12V CTRL2 FB, OVLO ..............8V CTRL1...

  • Page 3: Electrical Characteristics

    LTM8005 ELECTRICAL CHARACTERISTICS denotes the specifications which apply over the specified operating temperature range, otherwise specifications are at T = 25°C. CTRL1 = CTRL2 = PWM = 5V, unless otherwise noted (Note 2). PARAMETER CONDITIONS UNITS Minimum Input Voltage LED DC Current CTRL1 = 1.5V 1.65 CTRL1 = 0.6V CTRL1 = 0.2V 0.16 SW Current Limit SW R...
  • Page 4 LTM8005 ELECTRICAL CHARACTERISTICS denotes the specifications which apply over the specified operating temperature range, otherwise specifications are at T = 25°C. CTRL1 = CTRL2 = PWM = 5V, unless otherwise noted (Note 2). PARAMETER CONDITIONS UNITS EN/UVLO Threshold Voltage Falling 1.22 EN/UVLO Threshold Voltage Rising 1.24 EN/UVLO Pin Bias Current EN/UVLO = 1.15V, V = 12V...

  • Page 5: Typical Performance Characteristics

    LTM8005 TYPICAL PERFORMANCE CHARACTERISTICS = 25°C, unless otherwise noted. LED Current vs FB LED Current vs CTRL1 LED Current vs CTRL2 (CTRL1 = CTRL2 = V 0.25 0.50 0.75 1.25 1.50 0.25 0.50 0.75 1.25 1.50 CTRL1 VOLTAGE (V) CTRL2 VOLTAGE (V) 8005 G01 8005 G02 8005 G03 Switching Frequency...
  • Page 6 LTM8005 TYPICAL PERFORMANCE CHARACTERISTICS = 25°C, unless otherwise noted. DC2257A CISPR 22 Radiated DC2257A CISPR 22 Radiated Results Without Spread Spectrum Results With Spread Spectrum SPREAD SPECTRUM DISABLED SPREAD SPECTRUM ENABLED 1000 1000 FREQUENCY (MHz) FREQUENCY (MHz) 8005 G08 8005 G09 Output Disconnect Response Output Disconnect Response (Short Circuit)

  • Page 7: Pin Functions

    LTM8005 PIN FUNCTIONS GND (Bank 1, Pin K1, Pin K8): Tie these GND pins to a Rising hysteresis is generated by the external resistor local ground plane below the LTM8005 and the circuit divider, an internal 499kΩ resistor between EN/UVLO and components.
  • Page 8 LTM8005 PIN FUNCTIONS resistor. OPENLED status is updated only during PWM VC (Pin K3): Transconductance Error Amplifier Output Pin. high state and latched during PWM low state. If not used, Used to stabilize the control loop with an RC network. This leave floating or tie to GND.

  • Page 9: Block Diagram

    LTM8005 BLOCK DIAGRAM LTM8005 IVINP IVINN 499k EN/UVLO 0.068 OVLO BOOST LED CONTROLLER CTRL1 CTRL2 IVINCOMP 10nF RAMP SHORTLED OPENLED ISMON 8005 BD Rev. B For more information www.analog.com...

  • Page 10: Operation

    LTM8005 OPERATION The LTM8005 is a stand-alone non-isolated switching DC/ The LTM8005 features spread spectrum frequency DC regulator intended for LED driver applications. This modulation, which causes the switching frequency to µModule power converter provides a regulated current modulate to a frequency that is approximately 70% of from an input voltage range of 5V to 38V, and up to 38V the programmed value set by the RT resistor.

  • Page 11: Applications Information

    LTM8005 APPLICATIONS INFORMATION Programming the Turn-On and Turn-Off Thresholds LED Current Adjustment with the EN/UVLO Pin The maximum output LED current is internally set to 1.6A, The falling under-voltage lockout (UVLO) value can be typical. If both CTRL pins are tied to a voltage higher than accurately set by the resistor divider, as shown in Figure 1.
  • Page 12 LTM8005 APPLICATIONS INFORMATION LED driver, the output voltage can be programmed by 0.45A or FB drops below 1.19V (typical). The SHORTLED selecting the values of R5 and R6 (see Figure 3) according pin is asserted if the output current is about 2.4A or the FB to the following equation: pin falls below 300mV (typical) after initial start-up and SS reaches about 1.7V.
  • Page 13 LTM8005 APPLICATIONS INFORMATION Example: Calculate the resistor values required to increase 1.7 • 187kΩ R15 = the V range of a boost LED driver to 7.5:1 and have 0.35 • 17 – 1.2 • 3.4 – 0.85 • 0.7 OPENLED occur when V is 38V: = 249kΩ...
  • Page 14 LTM8005 APPLICATIONS INFORMATION PWM Dimming Control for Brightness operation. Lower frequency operation gives better perfor- mance at the cost of larger external component size. For There are two methods to control the LED current for an appropriate RT resistor value see Table 1. An external dimming using the LTM8005.
  • Page 15 LTM8005 APPLICATIONS INFORMATION Duty Cycle Considerations the ISP/ISN regulation loop, which consists of the output capacitance C and the dynamic resistance of the LED Switching duty cycle is a key variable defining converter load. The minimum C value of 10nF is integrated into FILT operation;...
  • Page 16 LTM8005 APPLICATIONS INFORMATION to do so with a 28µA source. Once above 1.7V, the pull- the capacitor value. An X7R type ceramic capacitor is a up source is disabled and a discharge current of about good choice because it has the least variation with tem- 2.8µA is activated.
  • Page 17 LTM8005 APPLICATIONS INFORMATION PCB Layout A few rules to keep in mind are: Most of the headaches associated with PCB layout have 1. Place the R and V components as close as been alleviated or even eliminated by the high level of possible to their respective pins.
  • Page 18 LTM8005 APPLICATIONS INFORMATION 5. Connect all of the GND connections to as large a cop- density of the thermal vias in Figures 9 and 10. The per pour or plane area as possible on the top layer. LTM8005 can benefit from the heat sinking afforded Avoid breaking the ground connection between the by vias that connect to internal GND planes at these external components and the LTM8005.
  • Page 19 LTM8005 is plugged into tion, many designers use FEA to predict thermal perfor- a live supply (see Analog Devices Application Note 88 mance. To that end, Page 2 of the data sheet typically for a complete discussion). The low loss ceramic capaci-...
  • Page 20 LTM8005 APPLICATIONS INFORMATION is determined with nearly all of the compo- physical operating condition of a µModule converter. θ JCTOP nent power dissipation flowing through the top of the Thus, none of them can be individually used to accurately package. As the electrical connections of the typical predict the thermal performance of the product.

  • Page 21: Typical Applications

    LTM8005 TYPICAL APPLICATIONS 1.2A at up to 17V LED String from 6V to 18V (Buck-Boost Mode) with Spread Spectrum 10µH 6V TO 18V IVINP IVINN 2× EN/UVLO 10µF 113k 2× STRING OVLO 10µF LTM8005 348k CTRL1 (OPTIONAL ULTRA-FAST 100k DIODE IF LED STRING IS FAR AWAY) CTRL2 ISMON...
  • Page 22 LTM8005 TYPICAL APPLICATIONS to 24V to 12V SEPIC with Current Limit COUP 3× 22µF SENSE2 4.4µH 4.4µH 6V TO 24V 38V MAX. IVINP IVINN 26V OVLO 4× EN/UVLO 4.7µF 90.9k OUT1 SENSE1 OUT2 OVLO 4× 150µF 22µF 21.5k LTM8005 3.56A CURRENT LIMIT CTRL1 107k CTRL2...

  • Page 23: Package Description

    LTM8005 PACKAGE DESCRIPTION Table 2. LTM8005 Pinout (Sorted by Pin Number) Name Name Name Name Name Name Name Name Name Name EN/UVLO OVLO ISMON IVINN IVINP IVINCOMP CTRL1 SHORTLED CTRL2 OPENLED RAMP PACKAGE PHOTO Rev. B For more information www.analog.com...
  • Page 24 LTM8005 PACKAGE DESCRIPTION Rev. B For more information www.analog.com...

  • Page 25: Revision History

    Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications For more information www.analog.com subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices.

  • Page 26: Typical Application

    2. Search using the Quick Power Search parametric table. Digital Power System Management Analog Devices’ family of digital power supply management ICs are highly integrated solutions that offer essential functions, including power supply monitoring, supervision, margining and sequencing, and feature EEPROM for storing user configurations and fault logging.

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