AME5259A Datasheet, PDF (1/21 Pages) Analog Microelectronics – 1.2A, 1.5MHz Synchronous Step-Down Converter

AME
AME5259A
n General Description
The AME5259A is a high efficiency monolithic synchro-
nous buck regulator using a constant frequency, current
mode architecture. Capable of delivering 1.2A output cur-
rent over a wide input voltage range from 2.5V to 5.5V.
Supply current with no load is 400µA and drops to<1µA
in shutdown. The 2.5V to 5.5V input Voltage range makes
the AME5259A ideally suited for single Li-Ion battery-
powered applications. 100% duty cycle provides low
dropout operation, extending battery life in portable sys-
tems. PWM pulse skipping mode operation provides
very low output ripple voltage for noise sensitive applica-
tions. At very light load, the AME5259A will automati-
cally skip pulses in pulse skip mode operation to main-
tain output regulation.
The internal synchronous switch increases efficiency
and eliminates the need for an external Schottky diode.
Low output voltages are easily supported with the 0.6V
feedback reference voltage. The AME5259A is available
in small DFN-6D, QFN-16C and SOT-25 packages.
Other features include soft start, lower internal refer-
ence voltage with 2% accuracy, over temperature protec-
tion, and over current protection.
n Features
l High Efficiency: Up to 95%
l Shutdown Mode Draws < 1µA Supply Current
l 2.5V to 5.5V Input Range
l Adjustable Output From 0.6V to V_IN
l 1.0V, 1.2V. 1.5V, 1.6V, 1.8V, 2.5V and 3.3V
Fixed/Adjustable Output Voltage
l 1.2A Output Current
l Low dropout Operation: 100% Duty Cycle
l No Schottky Diode Required
l 1.5MHz Constant Frequency PWM Operation
l Green Product Meet RoHS Standard
1.2A, 1.5MHz Synchronous
Step-Down Converter
n Applications
l Cellular Telephones
l Personal Information Applicances
l Wireless and DSL Modems
l MP3 Players
l Portable Instruments
n Typical Application
V_IN
CIN
4.7µF
CER
IN
SW
AME5259 A
2.2µH
EN
OUT
GND
VOUT
C_OUT
10µF
CER
Figure 1. Fixed Output Voltage
High Efficiency Step -Down Conventer
V_IN = 2.5V to 5.5V
VIN
IN
2.2µH
SW
CIN
4.7µF
CER
AME5259 A _CFWD
EN
FB
GND
VOUT
R1
150K
R2
75K
1.8V
COUT
10µF
CER
V_OUT=V_FB (R1+R2)/R2
Figure 2. Adjustable Output Voltage
1.8V at 1000mA Step-Down Requlator
C_FWD: 22pF~220pF
Rev.A.02
1