Document
Preliminary Datasheet
1.0MHz, 3.5A, Synchronous Step Down DC-DC Converter AP3435
General Description
The AP3435 is a high efficiency step-down DC-DC voltage converter. The chip operation is optimized by peak-current mode architecture with built-in synchronous power MOS switchers. The oscillator and timing capacitors are all built-in providing an internal switching frequency of 1MHz that allows the use of small surface mount inductors and capacitors for portable product implementations.
Integrated Soft Start (SS), Under Voltage Lock Out (UVLO), Thermal Shutdown Detection (TSD) and Short Circuit Protection are designed to provide reliable product applications.
The device is available in adjustable output voltage versions ranging from 0.8V to 0.9×VIN (2.7V≤VIN≤5.5V), and is able to deliver up to 3.5A.
The AP3435 is available in PSOP-8 package.
Features
• High Efficiency Buck Power Converter • Output Current: 3.5A • Low RDS(ON) Internal Switches:100mΩ (VIN=5V) • Adjustable Output Voltage from 0.8V to 0.9×VIN • Wide Operating Voltage Range: 2.7V to 5.5V • Built-in Power Switches for Synchronous
Rectification with High Efficiency • Feedback Voltage: 800mV • 1.0MHz Constant Frequency Operation • Thermal Shutdown Protection • Low Drop-out Operation at 100% Duty Cycle • No Schottky Diode Required • Input Over Voltage Protection
Applications
• LCD TV • Set Top Box • Post DC-DC Voltage Regulation • PDA and Notebook Computer
Dec. 2012 Rev. 1. 0
PSOP-8
Figure 1. Package Type of AP3435
BCD Semiconductor Manufacturing Limited 1
Preliminary Datasheet 1.0MHz, 3.5A, Synchronous Step Down DC-DC Converter AP3435 Pin Configuration
MP Package (PSOP-8)
18 27 36 45
Figure 2. Pin Configuration of AP3435 (Top View)
Pin Description
Pin Number
1 2 3 4
5 6 7 8
Pin Name
VCC NC GND
FB
EN
PGND SW VIN
Function
Supply input for the analog circuit
No connection
Ground pin Feedback pin. Receive the feedback voltage from a resistive divider connected across the output Chip enable pin. Active high, internal pull-high with 200kΩ resistor Power switch ground pin
Switch output pin
Power supply input for the MOSFET switch
Dec. 2012 Rev. 1. 0
BCD Semiconductor Manufacturing Limited 2
Preliminary Datasheet
1.0MHz, 3.5A, Synchronous Step Down DC-DC Converter AP3435
Functional Block Diagram
EN
5
VCC
1
VIN
8
Saw-Tooth Generator
Oscillator
Over-Current Comparator
FB 4
Bias Generator
Soft Start
Bandgap Reference
Current
+ Sensing
_ _+
+
Error Modulator Amplifier
Control Logic
Buffer & Dead Time
Control Logic
_
+ Over Voltage Comparator
Reverse Inductor Current Comparator
_ +
3
GND
Figure 3. Functional Block Diagram of AP3435
7 SW
6
PGND
Ordering Information
AP3435
-
Circuit Type
Package MP: PSOP-8
G1: Green TR: Tape & Reel
Package PSOP-8
Temperature Range
-40 to 80°C
Part Number AP3435MPTR-G1
Marking ID 3435MP-G1
Packing Type Tape & Reel
BCD Semiconductor's Pb-free products, as designated with "G1" in the part number, are RoHS compliant and green.
Dec..