VIPER27L datasheet(4/31 Pages) STMICROELECTRONICS

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Pin settings

VIPER27

4/31

Doc ID 15133 Rev 5

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

DIP7

SO16N

1...2

GND

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

section.

-4

N.A.

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

connected.

VDD

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

current of the external capacitor during start-up time.

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.

2. output voltage monitoring. A voltage exceeding VOVP threshold (see

Table 8 on page 7) shuts the IC down reducing the device consumption.

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

Control input for duty cycle control. Internal current generator provides

bias current for loop regulation. A voltage below the threshold VFBbm

activates the burst-mode operation. A level close to the threshold VFBlin

means that we are approaching the cycle-by-cycle over-current set point.

Brownout protection input with hysteresis. A voltage below the threshold

VBRth shuts down (not latch) the device and lowers the power

consumption. Device operation restarts as the voltage exceeds the

threshold VBRth + VBRhyst. It can be connected to ground when not used.

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.

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