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TOSHIBA BiCD Integrated Circuit Silicon Monolithic
TB62771FTG
Step-up DC/DC controller built in 4-channel sink driver for white LED
1. General description
TB62771FTG is a large-current LED driver IC incorporating
DC/DC controller for high-power LED systems.
This IC can drive high-intensity and large-current LED connected
to 4 constant current sinks.
This IC is for driving backlight of white LEDs for large LCD.
TB62771FTG
2. Features
Input voltage range : 4.75 V to 40 V
Weight : 0.03 g (TYP.)
Built in current mode DC/DC controller
Switching frequency:
Set by the resistance connected to RT terminal (200 kHz to 2.0 MHz), Synchronization with external clock
4ch constant current driver:
Sink current 20 mA to 150 mA
Current accuracy +/- 2% (ILED = 100 mA, between channels)
Control voltage for minimum OUT terminal 0.5 V (ILED = 150 mA)
Dimming control: Input PWM range 100 Hz to 30 kHz
Minimum pulse width of input PWM 330 ns
Detection circuit:
VIN under voltage lockout (UVLO(VIN))
VCC under voltage lockout (UVLO(VCC))
LED open detection
LED short detection (Set by the resistance connected to RSDT terminal)
Built in thermal shutdown circuit
Overvoltage detection (set by external resistance)
Soft start function
Output delay function
Shutdown consumption current 40 µA (max)
IC package:P-WQFN20-0404-0.50-002
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3. Block Diagram
TB62771FTG
PGND1 NDRV DRV
CS
RT
COMP
Step-up
Controller
OSC
Error
Amplifier
OVP
Over Voltage
Detector
Unused
Chanel
Detector
DIM
EN
EN
Soft Start
Current
Regulator
Logic
VIN
UVLO
Reference
Vref
VCC
AGND
UVLO
Ragulator
VCC
Thermal
Shutdown
Open
Detector
Fault Flag
Logic
Short
Detector
FLT
RSDT
OUT1
Current
Regulator1
Current
Regulator2
Current
Regulator3
Current
Regulator4
OUT2
OUT3
OUT4
LED current
Controller
SETI
PGND2
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4. Pin Assignment (Top view)
TB62771FTG
CS 16 16
PGND1 17 17
NDRV 18 18
DRV 19 19
VCC 20 20
TOP VIEW
10 10 DIM
9 9 AGND
8 8 RSDT
7 7 SETI
6 6 OVP
5. Marking (Top view)
X1 ,X2 Yearly code (last 2 digits of the year of manufacture)
X3 ,X4 Weekly code
X6 toX11 Lot trace code
3
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6. Pin function
TB62771FTG
No
Name
I/O (Note)
Function
1 VIN
2 EN
3 COMP
4 RT
5 FLT
6 OVP
7 SETI
8 RSDT
9 AGND
10 DIM
11 OUT1
12 OUT2
13 PGND2
14 OUT3
15 OUT4
16 CS
17 PGND1
18 NDRV
19 DRV
20 VCC
P Power supply input.
Input chip enable signal,
I EN=High: operation mode or standby mode,
EN=Low: shutdown mode.
O
Terminal for controlling compensation point of AMP that controls output
voltage. Connect RC between COMP and AGND.
I
Internal oscillator setting terminal.
Connect RT resistor to AGND.
Error signal output by fault protection control (Nch open drain) ,
O This terminal is set Low in detecting LED Open, LED Short, and thermal
shutdown. Connect a pull-up resistor of 10kfrom FLT to VCC.
Overvoltage threshold adjust input.
I Connect a divided resistance from the switching convertor output to OVP
and AGND. The OVP comparator reference is set 1.23V internally.
O LED current adjust input. Connect a resistor (RSETI) to AGND.
LED short detection adjusting input.
I Connect a divided resistance from VCC to AGND.
Connect RSDT directly to VCC to disable LED short detection.
P Ground for logic signal. Connect to PGND1, PGND2.
Digital PWM dimming input.
DIM = High: Operation mode
DIM = Low: Standby mode.
I Connect DIM to VCC if dimming control is not used (continuous constant
current operation).
*The minimum pulse width which can be inputted is 330 ns. When a pulse
of the width less than 330ns is input, it may not operate normally.
O
Constant current sink terminals to drive LED for channel 1.
This terminal is open drain output that sinks up to 150mA.
O
Constant current sink terminals to drive LED for channel 2.
This terminal is open drain output that sinks up to 150mA.
P Power Ground. Connect PGND2 to AGND and PGND1.
O
Constant current sink terminals to drive LED for channel 3.
This terminal is open drain output that sinks up to 150mA.
O
Constant current sink terminals to drive LED for channel 4.
This terminal is open drain output that sinks up to 150mA.
I
Current sense input It monitors the current of external power MOSFET
source.
P Power Ground. Connect PGND1 to AGND and PGND2.
O Switching n-MOSFET gate driver output.
Power Supply input for the control circuits of switching MOSFET gate.
I Connect Resistance between DRV and 5V regulator output VCC.
And connect DRV and PGND with minimum of 0.1μF Bypass capacitor.
5V Regulator Output.
O Connect minimum of 1.0μF capacitor between VCC and AGND as close
to the device as possible.
Note. : I: Input terminal
O: Output terminal
P: Power supply terminal
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7. Equivalent circuits of terminals
Pin No. Pin name
1 VIN
9 AGND
13 PGND2
17 PGND1
20 VCC
VIN
VCC
AGND
PGND1
PGND2
2 EN
EN
Equivalent circuit
VIN
3 COMP
COMP
AGND
VCC
AGND
AGND
VCC
4 RT
RT
AGND
VCC
5 FLT FLT
AGND
VCC
6
OVP
OVP
AGND
5
TB62771FTG
2013-05-23