Driver Controller. RT8492 Datasheet

RT8492 Controller. Datasheet pdf. Equivalent

RT8492 Datasheet
Recommendation RT8492 Datasheet
Part RT8492
Description High Voltage 4-CH LED Driver Controller
Feature RT8492; ® RT8492 High Voltage 4-CH LED Driver Controller General Description The RT8492 is a 4-CH LED driv.
Manufacture Richtek
Datasheet
Download RT8492 Datasheet




Richtek RT8492
®
RT8492
High Voltage 4-CH LED Driver Controller
General Description
The RT8492 is a 4-CH LED driver controller that delivers
well matched LED current to each channel of LED string.
With external current sources, the number of LEDs per
string is only limited by the current source and the VIN/
VOUT conditions. The current mode PWM boost type
controller operates at a programmable switching frequency
of up to 1MHz, with a wide VIN range covering from 9V to
32V. The switch driver is designed to drive industrial grade
high power MOSFETs.
The PWM loop selects and regulates the LED string with
the highest voltage string to 0.9V, thus allowing voltage
mismatches between the LED strings. The RT8492
automatically detects and excludes any open and/short
strings during operation from the PWM loop to prevent
VOUT from over voltage.
The RT8492 also provides LED short protection. If LED
short occurs and causes any LEDx but not all LEDx pin
voltage greater than 8V, the CAP pin is charged up by
internal 10μA. If the LED short condition lasts longer than
the CAP pin voltage reaches 3.5V, the FLAG pin will go
high and the GATE pin will be kept low immediately until
the CAP pin voltage drops below 3.5V. The delay time is
programmable by the capacitor at the CAP pin.
Features
Wide Operation Voltage Range : 9V to 32V
Programmable Channel Current
3% Current Matching Accuracy between Channels
Programmable Switching Frequency
Easy Analog and Digital Dimming Control
Programmable Soft-Start
LED Open Channel Detection and Protection
LED Short-Fault Detect Latch Off Multiple LED
Strings
Programmable Output Over Voltage Protection
Under Voltage Lockout and Thermal Shutdown
28-Lead TSSOP Package
Applications
Building and Street Lighting
LED TV Backlight
LED Monitor Backlight
Industrial Display Backlight
Simplified Application Circuit
VIN
R3
12V
CIN
CVCC
CB
RSET
RT8492
VCC
CAP
VBASE
GBIAS
GATE
ISENSE
ACTL
NC
FLAG
LED1
RSET
GATE1
SENSE1
L1
CT
Chip Enable
EN
SS
CSS
GND
LED4
GATE4
SENSE4
D1
COUT
MSW
RSENSE
M1
RS1
VOUT
4 x N LEDs
M4
RS4
Copyright ©2014 Richtek Technology Corporation. All rights reserved.
DS8492-06 October 2014
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
1



Richtek RT8492
RT8492
Ordering Information
RT8492
Package Type
C : TSSOP-28
Lead Plating System
G : Green (Halogen Free and Pb Free)
Note :
Richtek products are :
RoHS compliant and compatible with the current require-
ments of IPC/JEDEC J-STD-020.
Suitable for use in SnPb or Pb-free soldering processes.
Marking Information
RT8492GC : Product Number
RT8492
GCYMDNN
YMDNN : Date Code
Pin Configurations
(TOP VIEW)
VCC
VBASE
GBIAS
GATE
GND
ISENSE
RSET
EN
OVP
SS
VC
ACTL
FLAG
CAP
2
3
4
5
6
7
8
9
10
11
12
13
14
28
27
26
25
24
23
22
21
20
19
18
17
16
15
TSSOP-28
NC
NC
LED1
GATE1
SENSE1
LED2
GATE2
SENSE2
LED3
GATE3
SENSE3
LED4
GATE4
SENSE4
Copyright ©2014 Richtek Technology Corporation. All rights reserved.
www.richtek.com
2
is a registered trademark of Richtek Technology Corporation.
DS8492-06 October 2014



Richtek RT8492
RT8492
Functional Pin Description
Pin No.
1
2
3
Pin Name
Pin Function
VCC
Power Supply. For good bypass, a low ESR capacitor is needed between this pin
and GND.
VBASE
The External Gate Bias Supply is Driven by an External NPN Transistor. The base
of this NPN is tied to VBASE pin. The emitter of this NPN is tied to GBIAS pin. The
collector of this NPN is tied to VCC.
GBIAS
Internal Gate Driver Bias Voltage (around 9.5V). Need a good bypass capacitor
between this pin and GND.
4
GATE
Gate Pin of External MOSFET. For the Boost PWM control loop.
5 GND Ground.
Switch Current Sense. Connect a sense resistor from this pin to GND. The switch
6 ISENSE current sense signal is used for boost current mode PWM loop control and power
switch over current protection.
7
RSET
Switching Frequency Set. Put a resistor from RSET to GND to program the
switching frequency. fSW = 280kHz when RSET = 40k.
8 EN
Chip Enable (Active High).
9
OVP
Over Voltage Protection. OVP pin threshold is around 1.25V. Use a resistor divider
from output to GND to program the OVP level.
10 SS
Soft-Start Pin. Use a soft-start cap from SS pin to GND to program the soft-start time
period. Around 10A is sourcing out of SS pin.
11 VC
Loop Compensation.
12
ACTL
Analog/PWM Dimming Control. When used in analog dimming, ACTL control range
is from 0.4V to 1.4V.
Fault Indicator Output. Flag pin goes high in two conditions. As the OVP pin goes
high, the FLAG pin goes high without time delay. If the LED short condition occurs
13 FLAG and the CAP pin voltage is higher than 3.5V, the FLAG pin will go high and the
GATE pin will be pulled low and latched off. The latch-off condition can be reset by
EN pin or VCC pin.
14 CAP
The LED Short Detection Time Delay Programming. If LED short occurs and causes
any LEDx but not all LEDx pin voltage greater than 8V, the CAP pin is charged up
by internal 10A. If the LED short condition occurs and lasts longer than the CAP
pin voltage reaches 3.5V, the FLAG pin will go high. The delay time is
programmable by the capacitor at the CAP pin. The typical delay time is 80ms when
the capacitor at CAP pin is 47nF.
24, 21, 18, 15 SENSEx
25, 22, 19, 16 GATEx
26, 23, 20, 17 LEDx
27, 28
NC
Source Pin of External MOSFETx (x = 1 to 4).
The SENSEx pins are regulated around 440mV. Connect a sense resistor from this
pin to GND. The LED current is programmed by ILED = 440mV / (sense resistance)
when VACTL is greater than 1.4V.
Gate Pin of External MOSFETx (x = 1 to 4). For LED drivers.
LEDx Pin (x = 1 to 4) is Normally Regulated Around 0.9V. If LED short occurs and
causes any LEDx but not all LEDx pin voltage greater than 8V, the LED short
protection is triggered.
Connect to LED1.
Copyright ©2014 Richtek Technology Corporation. All rights reserved.
DS8492-06 October 2014
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
3







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