ZLED7001 datasheet(8/16 Pages) ETC2

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ZLED7001

Universal LED Driver with Temperature Compensation

Data Sheet

August 12, 2010

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2.3.

Input Voltage Regulator

The value and rating of the RIN input resistor must be selected as needed to drop the application supply

voltage (Vs) to the proper operating voltage for the ZLED7001 specified in section 1 (see equation (2) below).

When these conditions are met, the ZLED7001’s internal input voltage regulator maintains a stable 7.1V

(typical) at the VIN pin to power the ZLED7001. A low-equivalent-series-resistance (ESR) bypass capacitor is

required on the VIN pin to provide a low-impedance path for the GATE pin output driver’s high frequency

current.

The VIN pin draws an input current that is the sum of the 0.5mA (typical) required by the internal circuit and the

average current drawn by the GATE driver. The GATE driver current is primarily determined by the GATE

charge (QG) and switching frequency (fs) of the external MOSFET as shown in equation (1).









(1)

Where

fS = Switching frequency

= External MOSFET gate charge (refer to the MOSFET data sheet)

The input resistor RIN value is given by equation (2).

INDC





(2)

For two typical MOSFET types, the following IIN diagram will result:

Figure 2.1

Input Current

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