cat4104 ON Semiconductor, cat4104 Datasheet - Page 3

• Manufacturer Part Number: cat4104
• Description: 700 Ma Quad Channel Constant Current Led Driver
• Manufacturer: ON Semiconductor

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, T
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
“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
EN/PWM
LED CURRENT
QUIESCENT CURRENT
T
Symbol
PWRDWN
T
T
T
T
T
T
T
PS
LO
P1
P2
HI
R
F
SHUTDOWN 0 mA
SHUTDOWN 0 mA
SHUTDOWN
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
T
PS
T
P2
50%
AMB
Figure 1. CAT4104 EN/PWM Timing
= 25°C
T
HI
50%
T
P1
T
T
LO
R
LED
LED
LED
90%
10%
Conditions
I
I
I
I
I
I
I
I
I
LED
LED
LED
LED
LED
LED
LED
LED
LED
3
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
range of 1 µs.
To ensure that PWM pulses are recognized, pulse
width low time T
CAT4104 enters a “zero current” shutdown mode after
a 4ms delay (typical) when EN/PWM is held low.
= 175 mA
= 80 mA
= 175 mA
= 175 mA
= 80 mA
= 175 mA
= 80 mA
= 175 mA
= 80 mA
T
F
I
LED
=
R
1.2 V
SET
Min
1
5
x 100
LO
should be longer than 1 µs. The
POWERDOWN
T
0 mA
PWRDWN
Typ
600
400
300
700
440
360
320
1.5
1.3
4
PS
is very short, in the
Max
SHUTDOWN 0 mA
SHUTDOWN 0 mA
Doc. No. MD-4051 Rev. A
8
CAT4104
Units
ms
μs
μs
μs
ns
ns
ns
ns