600KHz, 18V，2A Synchronous Step-Down Converter
FEATURES
High Efficiency: Up to 98%
? 600KHz Frequency Operation
? 2A Output Current
? No Schottky Diode Required
? 4.0V to 18V Input Voltage Range
? 0.6V Reference
Slope Compensated Current Mode
Control for Excellent Line and
Load Transient Response
Integrated internal compensation
Stable with Low ESR Ceramic Output Capacitors
Over Current Protection with
Hiccup-Mode
? Thermal Shutdown
? Inrush Current Limit and Soft Start
? Available in SOT23-6 Package
-40°C to +85°C Temperature Range
APPLICATIONS
Distributed Power Systems
? Digital Set Top Boxes
? Flat Panel Television and Monitors
? Wireless and DSL Modems
? Notebook Computer
GENERAL DESCRIPTION
The AP9166 is a fully integrated, high
efficiency 2A synchronous rectified stepdown
converter. The AP9166 operates
at high efficiency over a wide output current
load range. This device offers two
operation modes, PWM control and PFM
Mode switching control, which allows a
high efficiency over the wider range of the
load. The AP9166 requires a minimum
number of readily available standard
external components and is available in a
6-pin SOT23-6 compliant package.
Internal Regulator
The AP9166 is a current mode step down DC/DC
converter that provides excellent transient response
with no extra external compensation components.
This device contains an internal, low resistance, high
voltage power MOSFET, and operates at a high
600K operating frequency to ensure a compact, high
efficiency design with excellent AC and DC
perbance.
Error Amplifier
The error amplifier compares the FB pin voltage with
the internal FB reference (VFB) and outputs a
current proportional to the difference between the
two. This output current is then used to charge or
discharge the internal compensation network to b
the COMP voltage, which is used to control the
power MOSFET current. The optimized internal
compensation network minimizes the external
component counts and simplifies the control loop
design.
Internal Soft-Start
The soft-start is implemented to prevent the
converter output voltage from overshooting during
startup. When the chip starts, the internal circuitry
generates a soft-start voltage (SS) ramping up from
0V to 0.81V. When it is lower than the internal
reference (REF), SS overrides REF so the error
amplifier uses SS as the reference. When SS is
higher than REF, REF regains control. The SS time
is internally fixed to 1.5 ms.
