CAT4101TV-T75 Datasheet, PDF (3/11 Pages) ON Semiconductor – 1 A Constant-Current LED Driver with PWM Dimming

CAT4101
RECOMMENDED EN/PWM TIMING
For 3.0 V ≤ VIN ≤ 5.5 V, over full ambient temperature range -40ºC to +85ºC.
Symbol Name
Conditions
Min
Typ
Max
Units
T_PS
Turn-On time, EN/PWM rising to I_LED
from Shutdown
I_LED = 1 A
I_LED = 350 mA
1.6
1.1
μs
T_P1
Turn-On time, EN/PWM rising to I_LED
I_LED = 1 A
I_LED = 350 mA
920
620
ns
T_P2
Turn-Off time, EN/PWM falling to I_LED
I_LED = 1 A
I_LED = 350 mA
440
310
ns
T_R LED rise time
T_F LED fall time
I_LED = 1 A
840
I_LED = 350 mA
390
ns
I_LED = 1 A
470
I_LED = 350 mA
350
ns
T_LO
T_HI
T_PWRDWN
EN/PWM low time
EN/PWM high time
EN/PWM low time to shutdown delay
1
μs
5
μs
8
ms
EN/PWM
T_HI
T_LO
T_PWRDWN
SHUTDOWN
T_P2
T_PS
LED CURRENT
50%
T_P1
50%
T_F
T_R
90%
I_LED = (1.2V/R_SET) x 400
SHUTDOWN 0mA
SHUTDOWN 0mA
10%
0mA
VIN QUIESCENT CURRENT
SHUTDOWN 0mA
SHUTDOWN 0mA
Figure 1. CAT4101 EN/PWM Timing
EN/PWM OPERATION
The EN/PWM pin has two primary functions. One
function enables and disables the device. The other
function turns the LED channel on and off for PWM
dimming control. The device has a very fast turn-on
time (from EN/PWM rising to LED on) and allows
“instant on” when dimming LED using a PWM signal.
Accurate linear dimming is compatible with PWM
frequencies from 100 Hz to 5 kHz for PWM duty cycle
down to 1%. PWM frequencies up to 50 kHz can be
supported for duty cycles greater than 10%.
When performing a combination of low frequencies
and small duty cycles, the device may enter
shutdown mode. This has no effect on the dimming
accuracy, because the turn-on time T_PS is very short,
in the range of 1 µs.
To ensure that PWM pulses are recognized, pulse
width low time T_LO should be longer than 1μs. The
CAT4101 enters a “zero current” shutdown mode after
a 5 ms delay (typical) when EN/PWM is held low.
© 2009 SCILLC. All rights reserved.
3
Characteristics subject to change without notice
Doc. No. MD-5036, Rev. D