CAT4104

© 2009 SCILLC. All rights reserved.

3

Doc. No. MD-5041 Rev. B

Characteristics subject to change without notice

RECOMMENDED EN/PWM TIMING

Min and Max values are over the recommended operating conditions unless specified otherwise.

Symbol

Name

Conditions

Min

Typ

Max

Units

from shutdown

1.5

1.3

μs

600

ns

400

300

ns

LED rise time

700

440

ns

LED fall time

360

320

ns

EN/PWM low time

1

μs

EN/PWM high time

5

μs

EN/PWM low time to shutdown delay

4

8

ms

Figure 1. CAT4104 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 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%.

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,

range of 1 µs.

To ensure that PWM pulses are recognized, pulse

CAT4104 enters a “zero current” shutdown mode after

a 4 ms delay (typical) when EN/PWM is held low.

EN/PWM

SHUTDOWN

POWERDOWN

SHUTDOWN 0 mA

SHUTDOWN 0 mA

0 mA

SHUTDOWN 0 mA

SHUTDOWN 0 mA

LED CURRENT

QUIESCENT CURRENT

50%

50%

90%

10%

x 100

1.2 V