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| CAT4104V-GT3 Datasheet, PDF (3/14 Pages) ON Semiconductor – 700 mA Quad Channel Constant Current LED Driver | |||
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CAT4104
RECOMMENDED EN/PWM TIMING
Min and Max values are over the recommended operating conditions unless specified otherwise.
Typical values are at VIN = 5.0 V, TAMB = 25°C
Symbol Name
Conditions
Min
Typ
Max
TPS
Turn-On time, EN/PWM rising to ILED
from shutdown
ILED = 175 mA
ILED = 80 mA
1.5
1.3
TP1
Turn-On time, EN/PWM rising to ILED ILED = 175 mA
600
TP2
Turn-Off time, EN/PWM falling to ILED
ILED = 175 mA
ILED = 80 mA
400
300
TR
LED rise time
ILED = 175 mA
700
ILED = 80 mA
440
TF
LED fall time
TLO
EN/PWM low time
ILED = 175 mA
360
ILED = 80 mA
320
1
THI
EN/PWM high time
5
TPWRDWN EN/PWM low time to shutdown delay
4
8
Units
μs
ns
ns
ns
ns
μs
μs
ms
EN/PWM
SHUTDOWN
TP2
TPS
LED CURRENT
50%
SHUTDOWN 0 mA
THI
TLO
TPWRDWN
POWERDOWN
SHUTDOWN 0 mA
TP1 TR
TF
ILED =
1.2 V
RSET
x 100
90%
50%
10%
0 mA
QUIESCENT CURRENT
SHUTDOWN 0 mA
Figure 1. CAT4104 EN/PWM Timing
SHUTDOWN 0 mA
EN/PWM OPERATION
The EN/PWM pin has two primary functions. One
function enables and disables the device. The other
function turns the LED channels 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
âinstant onâ 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 TPS is very short, in the
range of 1 µs.
To ensure that PWM pulses are recognized, pulse
width low time TLO should be longer than 1 µs. The
CAT4104 enters a âzero currentâ shutdown mode after
a 4 ms delay (typical) when EN/PWM is held low.
© 2009 SCILLC. All rights reserved.
3
Characteristics subject to change without notice
Doc. No. MD-5041 Rev. B
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