AAT1112IWP-0.6-T1 查看數據表（PDF） - Analog Technology Inc

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AAT1112IWP-0.6-T1

1.5A, 1.4MHz Step-Down Converter

Analog Technology Inc 

AAT1112

1.5A, 1.4MHz Step-Down Converter

Output regulation is maintained until the dropout

voltage, or minimum input voltage, is reached. At

1.5A output load, dropout voltage headroom is

approximately 200mV.

The AAT1112 typically achieves better than ±0.5%

output regulation across the input voltage and output

load range. A current limit of 2.0A (typical) protects

the IC and system components from short-circuit

damage. Typical no load quiescent current is 42µA.

Thermal protection completely disables switching

when the maximum junction temperature is detect-

ed. The junction over-temperature threshold is

140°C with 15°C of hysteresis. Once an over-tem-

perature or over-current fault condition is removed,

the output voltage automatically recovers.

Peak current mode control and optimized internal

compensation provide high loop bandwidth and

excellent response to input voltage and fast load

transient events. Soft start eliminates output volt-

age overshoot when the enable or the input voltage

is applied. Under-voltage lockout prevents spuri-

ous start-up events.

Control Loop

The AAT1112 is a peak current mode step-down

converter. The current through the P-channel

MOSFET (high side) is sensed for current loop

control, as well as short-circuit and overload pro-

tection. A fixed slope compensation signal is added

to the sensed current to maintain stability for duty

cycles greater than 50%. The peak current mode

loop appears as a voltage-programmed current

source in parallel with the output capacitor.

The output of the voltage error amplifier programs

the current mode loop for the necessary peak switch

current to force a constant output voltage for all load

and line conditions. Internal loop compensation ter-

minates the transconductance voltage error amplifi-

er output. The reference voltage is internally set to

program the converter output voltage greater than or

equal to 0.6V.

Soft Start/Enable

Soft start limits the current surge seen at the input

and eliminates output voltage overshoot. When

pulled low, the enable input forces the AAT1112 into

a low-power, non-switching state. The total input

current during shutdown is less than 1µA.

Current Limit and Over-Temperature

Protection

For overload conditions, the peak input current is

limited. To minimize power dissipation and stresses

under current limit and short-circuit conditions,

switching is terminated after entering current limit

for a series of pulses. Switching is terminated for

seven consecutive clock cycles after a current limit

has been sensed for a series of four consecutive

clock cycles.

Thermal protection completely disables switching

when internal dissipation becomes excessive. The

junction over-temperature threshold is 140°C with

15°C of hysteresis. Once an over-temperature or

over-current fault conditions is removed, the output

voltage automatically recovers.

Under-Voltage Lockout

Internal bias of all circuits is controlled via the VIN

input. Under-voltage lockout (UVLO) guarantees

sufficient VIN bias and proper operation of all inter-

nal circuitry prior to activation.

1112.2007.01.1.1

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