SM8136A

SEIKO NPC CORPORATION —7

Immediately after startup, the device operates in

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

2ms) to set the current for LEDs connected to the DIN pins.

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

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

(2) The LED drive starts immediately before the end of the LED turn-on delay time.

Switching to Standby Mode

The SM8136A operating mode switches from

×1.0/×1.5 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 auto-

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

I

When EN is LOW for longer than the CE hold time of 1.00ms (typ), the SM8136A switches to standby

mode. In standby mode, the internal circuits are reset, hence the drive current settings must be re-entered to

restart the device.

Soft start time and LED current

Switching to standby mode, and EN hold time

EN

LED current

(1)

(2)

Soft start time

typ: 2ms

LED ON

Dimming pulse enable

VIN

VIN High

CE hold time

typ: 1.00ms

EN

LED current

1.0 or 1.5

Standby

mode