LT3492 LINER [Linear Technology], LT3492 Datasheet

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LT3492

Manufacturer Part Number
LT3492
Description
Triple Output LED Driver with 3000:1 PWM Dimming
Manufacturer
LINER [Linear Technology]
Datasheet

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0
FEATURES
APPLICATIONS
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TYPICAL APPLICATION
True Color PWM™ Dimming Delivers Up to 3000:1
Dimming Ratio
Built-In Gate Driver for PMOS LED Disconnect
Three Independent Driver Channels with 600mA,
60V Internal Switches
Operates in Buck, Boost, Buck-Boost Modes
CTRL Pin Accurately Sets LED Current Sense
Threshold Over a Range of 10mV to 100mV
Adjustable Frequency: 330kHz to 2.1MHz
Open LED Protection
Wide Input Voltage Range:
Surface Mount Components
28-Lead (4mm × 5mm) QFN and TSSOP Packages
RGB Lighting
Billboards and Large Displays
Automotive and Avionic Lighting
Constant-Current Sources
Operation from 3V to 30V
Transient Protection to 40V
3V TO 24V
V
High Dimming Ratio Triple Output Buck-Mode LED Power Supply
IN
1μF
10 LEDs
PV
58V
TG1
IN
33μH
ISP1-3
ISN1-3
V
PWM1-3
SHDN
IN
SW1
330mΩ
0.3A
ISP1
ISN1
0.47μF 0.47μF
TG2
33μH
LT3492
SW2
GND
330mΩ
0.3A
ISP2
ISN2
33μH
SW3
330mΩ
0.3A
ISP3
ISN3
0.47μF
CTRL1-3
OVP1-3
TG3
TG1-3
V
FADJ
V
C1-3
REF
1μF
DESCRIPTION
The LT
to operate as a constant-current source and is ideal for
driving LEDs. The LT3492 works in buck, boost or buck-
boost mode. The LT3492 uses a fi xed frequency, current
mode architecture resulting in stable operation over a
wide range of supply and output voltages. A frequency
adjust pin allows the user to program switching frequency
between 330kHz and 2.1MHz to optimize effi ciency and
external component size.
The external PWM input provides 3000:1 LED dimming
on each channel. Each of the three channels has a built-in
gate driver to drive an external LED-disconnect P-channel
MOSFET, allowing high dimming range. The output current
range of each channel of the LT3492 is programmed with
an external sense resistor.
The CTRL pin is used to adjust the LED current either for
analog dimming or overtemperature protection.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. True Color PWM is a trademark of Linear Technology Corporation.
All other trademarks are the property of their respective owners. Protected by U.S. Patents,
including 7199560, 7321203, and others pending.
3
150k
49.9k
with 3000:1 PWM Dimming
1.3MHz
®
Triple Output LED Driver
10k
3492 TA01a
3492 is a triple output DC/DC converter designed
680pF
0.2A/DIV
0.5A/DIV
5V/DIV
PWM
I
LED
I
L
3000:1 PWM Dimming at 100Hz
1μs/DIV
LT3492
3492 TA01b
1
3492f

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LT3492 Summary of contents

Page 1

... The LT 3492 is a triple output DC/DC converter designed to operate as a constant-current source and is ideal for driving LEDs. The LT3492 works in buck, boost or buck- boost mode. The LT3492 uses a fi xed frequency, current mode architecture resulting in stable operation over a wide range of supply and output voltages. A frequency adjust pin allows the user to program switching frequency between 330kHz and 2.1MHz to optimize effi ...

Page 2

... LT3492IFE#PBF LT3492IFE#TRPBF LT3492EUFD#PBF LT3492EUFD#TRPBF LT3492IUFD#PBF LT3492IUFD#TRPBF Consult LTC Marketing for parts specifi ed with wider operating temperature ranges. *The temperature grade is identifi label on the shipping container. Consult LTC Marketing for information on non-standard lead based fi nish parts. *For more information on lead free part marking, go to: For more information on tape and reel specifi ...

Page 3

... FADJ = 1.5V (2.1MHz) FADJ = 0.5V (1.3MHz) FADJ = 0.1V (330kHz) Current Out of Pin, CTRL1-3 = 0.1V Current Out of Pin, FADJ = 0.1V Current Out of Pin, OVP1-3 = 0.1V PWM1 ISP1-3 = 48V ISP1-3 = 48V (Note 500mA (Note 3) SW SHDN = 0V PWM1 SHDN = 0V LT3492 MIN TYP MAX UNITS 2.1 2 100 103 mV l ...

Page 4

... Specifi cations over the –40°C to 125°C operating junction temperature range are assured by design, characterization and correlation with statistical process controls. The LT3492I is guaranteed over the full –40°C to 125°C operating junction temperature range. TYPICAL PERFORMANCE CHARACTERISTICS ...

Page 5

... CTRL (V) PMOS Turn On Waveforms 5V PWM 0V 60V TG 50V V = 60V 200ns/DIV 125 ISP Q FET = 6nC G LT3492 (T = 25°C unless otherwise noted) A Switch Frequency vs FADJ 2250 2000 1750 1500 1250 1000 750 500 250 0 100 125 0 0.2 0.4 0.6 0.8 FADJ (V) 3492 G05 V V Threshold vs V ...

Page 6

... LT3492 PIN FUNCTIONS CTRL1, CTRL2, CTRL3: LED Current Adjustment Pins. Sets voltage across external sense resistor between ISP and ISN pins of the respective converter. Setting CTRL voltage to be less than 1V will control the current sense voltage to be one-tenth of CTRL voltage. If CTRL voltage is higher than 1V, the default current sense voltage is 100mV. The CTRL pin must not be left fl ...

Page 7

... CTRL1 + A8 – CTRL BUFFER INTERNAL IN C3 REGULATOR SHDN AND UVLO V REF – REFERENCE Figure 1. LT3492 Block Diagram Working in Boost Confi guration C2 LED ARRAY I LED – M1 ISN1 TG1 EAMP + – – – SLOPE R2 20k V IN 200μ ...

Page 8

... The control circuitry, power switch etc., are replicated for each of the three converters. Figure 1 shows the shared circuits and only converter 1 circuits. If the SHDN pin is logic low, the LT3492 is shut down and draws minimal current from V logic high, the internal bias circuits turn on. The switching regulators start to operate when their respective PWM signal goes high ...

Page 9

... Selection of a higher switching frequency will allow use of low value external components and yield a smaller solution size and profi le cautionary note, operation of the LT3492 at a com- bination of high switching frequency with high output voltage and high switch current may cause excessive internal power dissipation ...

Page 10

... Proportionately higher values may be used if a lower switching frequency is selected. Several inductors that work well with the LT3492 are listed in Table 2. However, there are many other manufacturers and devices that can be used. Consult each manufacturer for more detailed information and their entire range of parts ...

Page 11

... To obtain good current regulation accuracy and eliminate sources of channel to channel coupling, the ISP and ISN inputs of each channel of the LT3492 should be run as separate lines back to the terminals of the sense resistor. Any resistance in series with ISP and ISN inputs should be minimized. Avoid ex- ...

Page 12

... I I SN1 SN2 0.3A 0. 0.22μF 0.22μ 33μH 33μH 33μ SW1 SW2 SW3 ISP1-3 ISN1 PWM1-3 LT3492 SHDN GND 3492 TA07b C1-C3 ISP3 1μF 3 330mΩ ISN3 0.3A C6 0.22μF D3 TG1-3 V C1-3 V REF CTRL1-3 10k 150k FADJ 470pF 49.9k 1.3MHz OVP1-3 3492 TA07a Effi ...

Page 13

... D1 D2 ISP1 ISP2 C3 1μF 1Ω 1Ω ISN1 ISN2 TG2 OVP1 100mA 12 LEDs 100mA 20k SW2 LT3492 GND 3492 TA03b LT3492 L3 22μH D3 ISP3 C4 1μF 1Ω ISN3 TG3 OVP2 OVP3 12 LEDs 100mA 20k 20k SW3 TG1-3 OVP1-3 18.2k V ...

Page 14

... D1 ISP1 C2 C3 1μF 1μF 1Ω 1Ω ISN1 M1 1M OVP1 12 LEDs 100mA 20k SW2 LT3492 GND Effi ciency vs PWM Duty Cycle for 200mA LEDs 3492 TA04b L3 22μ ISP2 ISP3 C4 1μF 1Ω ISN2 ISN3 M2 1M OVP2-3 12 LEDs ...

Page 15

... ISP1 C3 1μF 1Ω 1Ω ISN1 TG2 M1 M2 750k OVP1 100mA 9 LEDs 100mA 20k SW2 LT3492 GND 3492 TA08b LT3492 L3 15μH D3 ISP2 ISP3 C4 1μF 1Ω ISN2 ISN3 TG3 M3 750k 750k OVP2 OVP3 9 LEDs 100mA 20k 20k SW3 TG1-3 OVP1-3 18 ...

Page 16

... TG2 M2 C2 0.47μF 825k 10 LEDs 0.1A 20k L1 6.8μH D1 SW1 SW2 LT3492 GND C1: MURATA GRM55DR71H335KA0193 L1: TDK VLF5014AT-6R8MR99 C2: MURATA GRM21BR71H474KA88 L2: TDK VLF5014AT-229MR62 C3, C5: MURATA GRM31MR71H105KA88 L3: TDK VLF5014AT-330MR50 C4: MURATA GRM21BR71H104KA01B M1: ZETEX ZXMP3A13F D1: DIODES DFLS130 M2, M3 ZETEX ZXMP6A13F D2, D3: ROHM RB160M-60 3000:1 PWM Dimming at 100Hz for CH2 (Boost Mode) 5V/DIV 0 ...

Page 17

... TG2 M2 80.6k 10 LEDs 0. 0.47μF 0.47μF 5.6k M5 OVP2 OVP1 22μH 2k SW2 LT3492 GND Effi ciency vs PWM Duty Cycle for 200mA LEDs 3492 TA02b LT3492 C1-C3 ISP3 1μF 3 330mΩ ISN3 TG3 M3 80.6k 10 LEDs 0.3A C6 0.47μF 5. 22μ SW3 TG1-3 OVP1-3 10k ...

Page 18

... LT3492 PACKAGE DESCRIPTION 4.75 (.187) 6.60 0.10 4.50 0.10 SEE NOTE 4 RECOMMENDED SOLDER PAD LAYOUT 4.30 – 4.50* (.169 – .177) 0.09 – 0.20 (.0035 – .0079) (.020 – .030) NOTE: 1. CONTROLLING DIMENSION: MILLIMETERS 2. DIMENSIONS ARE IN MILLIMETERS (INCHES) 3. DRAWING NOT TO SCALE 18 FE Package 28-Lead Plastic TSSOP (4.4mm) (Reference LTC DWG # 05-08-1663) ...

Page 19

... UFD Package 28-Lead Plastic QFN (4mm × 5mm) (Reference LTC DWG # 05-08-1712 Rev B) 0.70 0.05 3.65 0.05 PACKAGE OUTLINE 3.50 REF 4.10 0.05 5.50 0.05 0.75 0.05 4.00 0.10 (2 SIDES) 3.50 REF 0.200 REF 0.00 – 0.05 LT3492 PIN 1 NOTCH 2.50 REF R = 0. 0.115 45 CHAMFER TYP TYP 27 28 0.40 0. 3.65 0.10 2.65 0.10 (UFD28) QFN 0506 REV B 0 ...

Page 20

... ISP3 0.1μF 1μF 0.1μF 1μ SW2 SW3 TG1-3 OVP1-3 V C1-3 LT3492 V REF CTRL1-3 150k GND FADJ 49.9k D1-D3: ROHM RB160M-60 1.3MHz L1-L3: TDK VLF5014AT-220MR62 M1-M3: ZETEX ZXMP6A13F COMMENTS 30V 4mm × 5mm QFN and TSSOP16E Packages 36V < ...

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