cat4101 ON Semiconductor, cat4101 Datasheet - Page 3

• Manufacturer Part Number: cat4101
• Description: 1 A Constant-current Led Driver With Pwm Dimming
• Manufacturer: ON Semiconductor

RECOMMENDED EN/PWM TIMING
For 3.0 V ≤ VIN ≤ 5.5 V, over full ambient temperature range -40ºC to +85ºC.
EN/PWM
LED CURRENT
VIN QUIESCENT CURRENT
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%.
© 2009 SCILLC. All rights reserved.
Characteristics subject to change without notice
T
Symbol
PWRDWN
T
T
T
T
T
T
T
PS
P1
P2
LO
HI
R
F
SHUTDOWN 0mA
SHUTDOWN 0mA
Name
Turn-On time, EN/PWM rising to I
from Shutdown
Turn-On time, EN/PWM rising to I
Turn-Off time, EN/PWM falling to I
LED rise time
LED fall time
EN/PWM low time
EN/PWM high time
EN/PWM low time to shutdown delay
SHUTDOWN
T
PS
T
P2
50%
Figure 1. CAT4101 EN/PWM Timing
T
HI
50%
T
P1
LED
LED
LED
T
LO
T
R
Conditions
I
I
I
I
I
I
I
I
I
I
LED
LED
LED
LED
LED
LED
LED
LED
LED
LED
90%
10%
3
= 1 A
= 350 mA
= 1 A
= 350 mA
= 1 A
= 350 mA
= 1 A
= 350 mA
= 1 A
= 350 mA
T
F
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
in the range of 1 µs.
To ensure that PWM pulses are recognized, pulse
width low time T
CAT4101 enters a “zero current” shutdown mode after
a 5 ms delay (typical) when EN/PWM is held low.
I
LED
= (1.2V/R
Min
1
5
SET
LO
) x 400
should be longer than 1μs. The
Typ
920
620
440
310
840
390
470
350
1.6
1.1
T
0mA
PWRDWN
Max
8
Doc. No. MD-5036, Rev. D
PS
SHUTDOWN 0mA
SHUTDOWN 0mA
is very short,
CAT4101
Units
ms
μs
ns
ns
ns
ns
μs
μs