TLC59283 Datasheet, PDF (18/25 Pages) Texas Instruments – 16-Channel, Constant-Current LED Driver with Pre-Charge FET

TLC59283
SBVS199A – JUNE 2012 – REVISED JUNE 2012
www.ti.com
The TLC59283 has an internal pre-charge FET to prevent ghosting, as shown in Figure 24. When a small delay
after PWM control for a single common line completes, the FET pulls OUTn up to V_CC. The charge current does
not flow to C0 through LED1-0 when SWMOS1 is turned on and the ghosting is eliminated at (3). However,
depending on the LED anode voltage, the number of LEDs in series, the LED forward voltage, and the
TLC59283 V_CC supply voltage, there may not be a great enough ghost-canceling effect.
VLED
(LED Power-Supply)
BLANK
SW
PMOS1
LED1-1
LED1-2
SW
NMOS1
VLED
LED1-0
SW
PMOS0
C0
C1
Disappearing I_CHRG
COM1
¼
Parasitic Capacitor
C2
COM0
SW
NMOS0
VCC
LED0-0
LED0-1
LED0-2
OUT0
OUT1
¼
OUT2
Pre-Charge FET
Timing
Control
OUT0
ON
TLC59283
LED Driver
Constant-Current
Output
OUT0
ON
OUT0
ON
PCHGON
¼
SW
PMOS0
SW
NMOS0
SW
PMOS1
SW
NMOS1
BLANK
OUT0
PCHGON
Signal
ON
OFF
ON
OFF
ON
OFF
ON
OFF
High
Low
ON
OFF
ON
OFF
OUT0
Voltage
VLED
VLED - V_F
LED0-0
Current
LED1-0
Current
20 mA
0 mA
20 mA
0 mA
COM0 is VLED level.
COM0 is GND level.
COM1 is VLED level.
COM1 is GND level.
VCC - 1.4 V (typ)
V_CHG
GND
(1) (2)
(3)
(4)
Ghost phenomenon not seen
Figure 24. LED Ghost-Lighting Mechanism by Pre-Charge FET
18
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