SM8135A

SEIKO NPC CORPORATION —8

Immediately after startup, the device operates in

×1.5 mode for a fixed interval (soft start time: approximately

1.43ms) to set the current for LEDs connected to the DIN pins. After the soft start time has elapsed, the LEDs

are turned ON. Approximately 2ms is required for the LED drive current to reach the set drive value.

(1) If the EN signal is input after power is applied, the soft start time begins on the EN rising edge. The PWM

signal input for dimming is active during the soft start time.

(2) After the soft start time (1.43ms) has elapsed, the LEDs are turned ON. Approximately 2ms is required for

LED drive current to reach set values.

Switching to Standby Mode

The SM8135A switches from

×1.0/×1.5/×2.0 mode to standby mode if EN goes LOW and stays LOW for an

interval of 1.00ms (typ). This function is used to switch the internal circuits to standby mode automatically

when the LEDs turn OFF in order to reduce current consumption.

I

If EN is LOW for longer than the enable hold time of 1.00ms (typ), the SM8135A switches to standby mode.

In standby mode, the internal circuits are reset.

Soft start time and LED current

EN input signal and internal enable signal “CE”

EN input signal

LED current

(1)

(2)

typ: 1.43ms

Soft start time

LED ON

typ: 2ms

CE hold time

typ: 1.00ms

EN

LED current

1.0 or 1.5

Standby

mode