ZXLD1350Q Просмотр технического описания (PDF) - Diodes Incorporated.

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ZXLD1350Q

AUTOMOTIVE COMPLIANT 350mA BUCK LED DRIVER

Diodes Incorporated. 

ZXLD1350Q

Device Description (Cont.)

Switching Thresholds

With VADJ = VREF, the ratios of R1, R2 and R3, define an average VSENSE switching threshold of 100mV (measured on the ISENSE pin with respect

to VIN). The average output current IOUTnom is then defined by this voltage and RS according to:

IOUTnom = 100mV/RS

Nominal ripple current is ±15mV/RS.

Adjusting Output Current

The device contains a low pass filter between the ADJ pin and the threshold comparator and an internal current limiting resistor (200k nom)

between ADJ and the internal reference voltage. This allows the ADJ pin to be overdriven with either DC or pulse signals to change the VSENSE

switching threshold and adjust the output current. The filter is third order, comprising three sections, each with a cut-off frequency of nominally

4kHz.

Details of the different modes of adjusting output current are given in the applications section.

Output Shutdown

The output of the low pass filter drives the shutdown circuit. When the input voltage to this circuit falls below the threshold (0.2V nom), the internal

regulator and the output switch are turned off. The voltage reference remains powered during shutdown to provide the bias current for the

shutdown circuit. Quiescent supply current during shutdown is nominally 15mA and switch leakage is below 1mA.

Typical Operating Waveforms [VIN = 12V, RS = 0.3, L = 100μH]

Normal Operation. Output Current (Ch3) and LX Voltage (Ch1)

Start-up Waveforms. Output Current (Ch3), LX Voltage (Ch1) and

VADJ (Ch2)

ZXLD1350Q

Document number: DS37076 Rev. 2 - 2

6 of 21

www.diodes.com

September 2017

© Diodes Incorporated

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