Short Circuit Protection

PCB Layout Check List

Channel 1:

The swich peak current is limited cycle-by-cycle

to

a typical vaule in the event of an output

voltage short circuit. The device operates with a

frequency of 1MHz and minimum duty clycle.

Therefore the average input current is typical

350mA(Vin=3.3V).

Channel 2:

When the converter output is shorted or the

device is overloaded,each high-side MOSFET

current-limit event (3A typ) turns off the high-side

MOSFET and turns on the low-side MOSFET. A

internal counter is used to count the each

cur rent-limit event. The counter is reset after

consecutive high-side MOSFETs turn on without

r e a c h i n g cu r r e n t li m it . I f t h e c u rr e n t -l i m i t

condition persists, the counter fills up. The

control logic then stops both high-side and low-

side MOSFETs and waits for a hiccup period,

before attemping a new soft-start sequence. The

counter bits is decided by Vfb voltage. If Vfb

0 2, the counter is 3-bit counter; if Vfb>0.2 the

counter is 6-bit counter. The typical hicuup made

duty cycle is 1.7%. The hiccup mode is disable

during soft-start time.

When laying out the printed circuit board, the

following checklist should be used to ensure

proper operation of the PAM2319. Check the

following in your layout:

1.

The input capacitor should be close to IC as

close as possible.

2.

Minimize the switching loop area to avoid

excessive switching noise.

3.

Two parts GND should be separately layout

to avoid disturbing by each other.

4.

Must put a small decoupling capacitor

between Vin2 Pin and AGND2 Pin.

5.

Vo2 output capacitor should be close to

o u t p u t c o n n e c t o r t o m i n i m i z e P C B t r a c e

resistance affect on ripple voltage. Recommend

use two output capacitor, one close to inductor

and IC, another close to output connector.

6.

PGND1 Pin should not directly connect to the

thermal pad (PGND), it should connect to input

capacitor GND then to other GND.

7.

AGND should connect to PGND at input

capacitor GND.

8.

For the good thermal dissipation, PAM2316

has a heat dissipate pad in the bottom side, it

should be soldered to PCB surface. For the

copper area can't be large in the component side,

so we can use multiple vias connect to other side

of the PCB.

9.

Avoid using vias in the high-current paths. If

vias are unavoidable, use multiple vias in parallel

to reduce resistance and inductance.

≤

.

11

,

Power Analog Microelectronics Inc

www.poweranalog.com

PAM2319

Dual High-Efficiency PWM Step-Down DC-DC Coverter

12/2011 Rev1.1