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Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com

201998B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 20, 2013

AAT1162

12V, 1.5A Step-Down DC/DC Converter

DATA SHEET

High efficiency is maintained under light load conditions

by automatically switching to variable frequency Light

Load control. In this condition, transition losses are

reduced by operating at a lower frequency at light

loads.

Short-Circuit Protection

The AAT1162 uses a cycle-by-cycle current limit to pro-

tect itself and the load from an external fault condition.

When the inductor current reaches the internally set

3.0A current limit, the P-channel MOSFET switch turns

off and the N-channel synchronous rectifier is turned on,

limiting the inductor and the load current.

During an overload condition, when the output voltage

drops below 50% of the regulation voltage (0.3V at FB),

the AAT1162 switching frequency drops by a factor of 4.

This gives the inductor current ample time to reset dur-

ing the off time to prevent the inductor current from

rising uncontrolled in a short-circuit condition.

Thermal Protection

The AAT1162 includes thermal protection that disables

the regulator when the die temperature reaches 140ºC.

It automatically restarts when the temperature decreas-

es by 25ºC or more.

Applications Information

Setting the Output Voltage

Figure 1 shows the basic application circuit for the

AAT1162 and output setting resistors. Resistors R1 and

R2 program the output to regulate at a voltage higher

than 0.6V. To limit the bias current required for the

external feedback resistor string while maintaining good

noise immunity, the minimum suggested value for R2 is

5.9kΩ. Although a larger value will further reduce quies-

cent current, it will also increase the impedance of the

feedback node, making it more sensitive to external

noise and interference. Table 1 summarizes the resistor

values for various output voltages with R2 set to either

5.9kΩ for good noise immunity or 59kΩ for reduced no

load input current.

PGND

AGND

LX

LX

IN

IN

EN

DGND

FB

AAT1162

C6

10μF

VIN 4.5V- 13.2V

L1

3.8μH

C1

100pF

C3

22μF

R3

432k

Ω

R6

59k

Ω

VOUT

5V, 1.5A

3

5

4

6

9

2

1

11

10

AIN

7

DGND

LDO

DGND

COMP

LX

DGND

R5

24k

Ω

C7

330pF

C9

1μF

C2

0.1μF

R4

10

Ω

14

8

13

16

EP1

EP2

C8

1μF

Figure 1: Typical Application Circuit.

The adjustable feedback resistors, combined with an

external feed forward capacitor (C1 in Figure 1), deliver

enhanced transient response for extreme pulsed load

applications. The addition of the feed forward capacitor

typically requires a larger output capacitor C3 for stabil-

ity. Larger C1 values reduce overshoot and undershoot

during startup and load changes. However, do not

exceed 470pF to maintain stable operation.