AAT2114A Datasheet, PDF (10/16 Pages) Skyworks Solutions Inc. – 2.5A Low-Noise, Fast Transient 3MHz Step-Down Regulator

DATA SHEET
AAT2114A
2.5A Low-Noise, Fast Transient 3MHz Step-Down Regulator
Functional Block Diagram
VCC
VP
Slope
Compensation
FB
0.6V
SGND
REF
EN
OSC
Control
Logic
VP
Temperature
Sensing
LX
PGND
Functional Description
The AAT2114A is a high performance 2.5A monolithic
step-down converter operating at a 3MHz switching fre-
quency. It minimizes external component size, optimizes
efficiency over the complete load range, and produces
reduced ripple and spectral noise. Apart from the small
bypass input capacitor, only a small L-C filter is required
at the output. Typically, a 0.47μH inductor and a 22μF
ceramic capacitor are recommended for a 1.2V output
(see table of recommended values).
Light load operation maintains high efficiency, low ripple
and low spectral noise even at lower currents (typically
<150mA).
The current limit of 4A (typical) protects the IC and sys-
tem components from short-circuit damage. Typical no
load quiescent current is 70μA.
Thermal protection completely disables switching when
the maximum junction temperature is detected. The
junction over-temperature threshold is 140°C with 15°C
of hysteresis. Once an over-temperature or over-current
fault condition is removed, the output voltage automati-
cally recovers.
Peak current mode control and optimized internal com-
pensation provide high loop bandwidth and excellent
response to input voltage and fast load transient events.
Soft start eliminates output voltage overshoot when the
enable or the input voltage is applied. Under-voltage
lockout prevents spurious start-up events.
Control Loop
The AAT2114A is a peak current mode step-down con-
verter. The current through the P-channel MOSFET (high
side) is sensed for current loop control, as well as short
circuit and overload protection. A fixed slope compensa-
tion signal is added to the sensed current to maintain
stability for duty cycles greater than 50%. The peak cur-
rent mode loop appears as a voltage-programmed cur-
rent 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 determines the
transconductance voltage error amplifier output. The
0.6V reference voltage is internally set to program the
converter output voltage greater than or equal to 1.0V.
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 AAT2114A into a low-power,
non-switching state. The total input current during shut-
down is less than 1μA.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [e-mail] • www.skyworksinc.com
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202004C • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 18, 2013