AS1337 datasheet(2/14 Pages) AMSCO

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AS1337

Datasheet - P i n A s s i g n m e n t s

4 Pin Assignments

Figure 2. Pin Assignments (Top View)

Pin Descriptions

Table 1. Pin Descriptions

Pin Name

Pin Number

Description

VOUT

Output Voltage. Bias is derived from VOUT when VOUT exceeds VIN. PCB trace

length from VOUT to the output filter capacitor(s) should be as short and wide as

is practical.

Switch Pin. Connect an inductor between this pin and VIN. Keep the PCB trace

lengths as short and wide as is practical to reduce EMI and voltage overshoot. If

the inductor current falls to zero, or pin EN is low, an internal 100

Ω anti-ringing

switch is connected from this pin to VIN to minimize EMI.

Note: An optional Schottky diode can be connected between this pin and VOUT.

PGND

Power Ground. Provide a short, direct PCB path between this pin and the out-

put capacitor(s).

GND

Ground

Enable Pin. Logic controlled enable input.

1 = Normal operation

0 = Shutdown

Note: In a typical application, EN should be connected to VIN through a 1M

pull-up resistor.

POK

POK. High when VOUT is within regulation.

VIN

Input Voltage. The AS1337 gets its start-up bias from VIN unless VOUT exceeds

VIN, in which case the bias is derived from VOUT. Thus, once started, operation

is completely independent from VIN. Operation is only limited by the output

power level and the internal series resistance of the supply.

Feedback Pin. Feedback input to the gm error amplifier. Connect a resistor

divider tap to this pin. The output voltage can be adjusted from 2.5V to 5V by:

VOUT = 1.23V[1 + (R1/R2)]

GND

Exposed Pad Ground

5 EN

PGND

VOUT

6POK

7VIN

8FB

AS1337

GND

9GND

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