TPS61196 Datasheet, PDF (1/30 Pages) Texas Instruments – 6-String 400-mA WLED Driver with Independent PWM Dimming for Each String

www.ti.com
TPS61196
SLVSBG1C – OCTOBER 2012 – REVISED FEBRUARY 2013
6-String 400-mA WLED Driver with Independent PWM Dimming for Each String
Check for Samples: TPS61196
FEATURES
1
• 8V to 30V Input Voltage
• Up to 120V Output Voltage
• 100KHz to 800kHz Programmable Switching
Frequency
• Adaptive Boost Output for LED Voltages
• Six Current Sinks, 200mA Continuous Output /
400mA Pulse Output for Each String
• ±1.5% Current Matching Between Strings
• High Precision PWM Dimming Resolution up
to 5000:1
• Programmable Over-voltage Threshold at
Output and Each Current Sink
• Programmable Under-voltage Threshold at
Input with Adjustable Hysteresis
• Adjustable Soft Start Time Independent of
Dimming Duty Cycle
• Built-in LED Open/Short Protection
• Built-in Schottky Diode Open/Short Protection
• Built-in ISET Short Protection
• Built-in IFB Short Protection
• Thermal Shutdown
• 28L HTSSOP Package with PowerPAD
APPLICATIONS
• LCD TV Backlight
• Scan Mode LCD TV Backlight
DESCRIPTION
The TPS61196 provides a highly integrated solution
for LCD TV backlight with an independent PWM
dimming function for each string. This device is a
current mode boost controller driving up to six WLED
strings with multiple LEDs in series. Each string has
an independent current regulator providing a LED
current adjustable from 50mA to 400mA within ±1.5%
matching accuracy. The minimal voltage at the
current sink is programmable in the range of 0.3V to
1.0V to fit with different LED current settings. The
input voltage range for TPS61196 is from 8V to 30V.
The TPS61196 adjusts the boost controller's output
voltage automatically to provide only the voltage
required by the LED string with the largest forward
voltage drop plus the minimum required voltage at
that string's IFB pin, thereby optimizing the driver's
efficiency. Its switching frequency is programmed by
an external resistor from 100kHz to 800kHz.
The TPS61196 supports direct PWM brightness
dimming. Each string has an independent PWM
control input. During the PWM dimming, the LED
current is turned on/off at the frequency and duty
cycle which are determined by the external PWM
signal. The PWM frequency ranges from 90Hz to
22kHz.
The TPS61196 integrates over current protection,
output short circuit protection, ISET short to ground
protection, diode open and short protection, LED
open and short protection, and over temperature
shutdown circuit. In addition, the TPS61196 can
detect the IFB pin short to ground to protect the LED
string. The device also provides programmable input
under-voltage lockout threshold and output over-
voltage protection threshold.
The TPS61196 has a built-in linear regulator which
steps down the input voltage to the VDD voltage for
powering the internal circuitry. An soft start circuit is
implemented internally to work with an external
capacitor to adjust the soft startup time to minimize
the in-rush current during boost converter startup.
The device is available in 28-pin HTSSOP package
with powerPAD providing good thermal performance.
SIMPLIFIED SCHEMATIC CIRCUIT
VIN = 24V
L1
68mH
D1
EC1
100mF
C1
10mF
C4
10nF
R5
200k
C2
2.2mF
R1
182k
VIN
UVLO
R2
24.9k
VDD
C3
1.0mF
TPS61196
GDRV
ISNS
PGND
OVP
COMP
FSW
REF
EN
FAULT
PWM1
PWM2
PWM3
PWM4
PWM5
PWM6
IFB1
IFB2
IFB3
IFB4
IFB5
IFB6
IFBV
FBP
ISET
Thermal pad AGND
R19
3
R6
200
C5
470pF
EC2
100mF
Q1
R7
0.1
R3
255k
R4
10k
C7
2.2mF
R9
200k
R8
150k
C6
47nF
C8
160pF
R11
37.4k
R12
196k
R10
60.4k
C9
0.1mF
R13 R14 R15 R16 R17 R18
10M 10M 10M 10M 10M 10M
Figure 1. Typical Application of TPS61196
1
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2012–2013, Texas Instruments Incorporated