Pin settings

VIPER38

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DocID025703 Rev 2

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Pin settings

Figure 3. Connection diagram (top view)

Note:

The copper area for heat dissipation has to be designed under the DRAIN pins.

Table 2. Pin description

SO16N

Name

Function

1, 2

GND

Device ground and source of the power MOSFET.

3

N.C.

Not connected.

4N.A.

Not available for user. This pin is mechanically connected to the

controller die pad of the frame. In order to improve the noise immunity,

is highly recommended connect it to GND (pin 1-2).

5VDD

Supply voltage of the control section. This pin also provides the charging

current of the external capacitor during startup.

6CONT

Control pin. The following functions can be selected:

1. current limit setpoint adjustment. The default value (set internally) of the cycle-

by-cycle current limit can be reduced by connecting an external resistor to ground.

Table 8: Controller section on page 9) shuts the IC down, reducing device

consumption. This function is strobed and digitally filtered for high noise immunity.

7FB

Control input for duty cycle control. The internal current generator provides bias

approaching the cycle-by-cycle overcurrent setpoint.

8EPT

This pin allows the connection of an external capacitor for extra power

management. If the function is not used, the pin has to be connected to GND.

9...12

N.C.

Not connected.

13...16

DRAIN

High-voltage drain pin. The built-in high-voltage switched startup bias current is

drawn from this pin too. These pins are connected to the metal frame to facilitate

heat dissipation.