Pin settings

VIPER28

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Doc ID 15028 Rev 5

3

Pin settings

Figure 3.

Connection diagram (top view)

Note:

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

Table 3.

Pin description

Pin n.

Name

Function

SDIP10

DIP-7

SO16N

1

1

1...2

GND

This pin represents the device ground and the source of the power section.

--

4

N.A.

Function: Not available for user. It can be connected to GND (pins 1-2) or left

not connected.

225

VDD

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

current of the external capacitor during start-up time.

3

3

6

CONT

Control pin. The following functions can be selected:

1. current limit set point adjustment. The internal set default value of the cycle-

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

resistor.

on page 7) shuts the IC down reducing the device consumption. This function

is strobed and digitally filtered for high noise immunity.

447

FB

Control input for duty cycle control. Internal current generator provides bias

approaching the cycle-by-cycle over-current set point.

558

EPT

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

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

6...10

7,8

13...16 DRAIN

High voltage drain pin. The built-in high voltage switched start-up bias current

is drawn from this pin too. Pins connected to the metal frame to facilitate heat

dissipation.