Diodes AP65550 User Manual
Description, Features, Pin assignments
AP65550
Document number: DS36336 Rev. 2 - 2
1 of 14
www.diodes.com
April 2014
© Diodes Incorporated
AP65550
5A, 18V, 650kHz ADAPTIVE COT STEP-DOWN CONVERTER
Description
The AP65550 is an adaptive constant on-time mode synchronous
buck converter providing high efficiency, excellent transient response
and high DC output accuracy for low-voltage regulation in digital TV
and monitor.
The constant-on-time control scheme handles wide input/output
voltage ratios and provides low external component count. The
internal proprietary circuit enables the device to adopt both low
equivalent series resistance (ESR) output capacitors, such as SP-
CAP or POSCAP and ultra-low ESR ceramic capacitors.
The adaptive on-time control supports seamless transition between
continuous conduction mode (CCM) at higher load conditions and
discontinuous conduction mode (DCM) at lighter load conditions.
DCM allows AP65550 maintain high efficiency at light load conditions.
The AP65550 also features programmable soft-start, UVLO, OTP and
OCP to protect the circuit.
This IC is available in SO-8EP package.
Features
Fixed Frequency Emulated Constant On-time Control
Good Stability Independent of the Output Capacitor ESR
Fast Load Transient Response
Synchronous Rectification: 65mΩ Internal High-side Switch and
36mΩ Internal Low-side Switch
Wide Input Voltage Range: 4.5V to 18V
Output Voltage Range: 0.76V to 6V
5A Continuous Output Current
650kHz Switching Frequency
Built-in Over Current Limit
Built-in Thermal Shutdown Protection
Programmable Soft-start
Pre-biased Start-up
Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2)
Halogen and Antimony Free. “Green” Device (Note 3)
Pin Assignments
SW
VREG5
SS
EN
BS
GND
VIN
( Top View )
1
2
3
4
8
7
6
5
FB
SO-8EP
Applications
Gaming Consoles
Flat Screen TV sets and Monitors
Set Top Boxes
Distributed power systems
Home Audio
Consumer electronics
Network Systems
FPGA, DSP and ASIC Supplies
Green Electronics
Notes:
1. No purposely added lead. Fully EU Directive 2002/95/EC (RoHS) & 2011/65/EU (RoHS 2) compliant.
2. See http://www.diodes.com/quality/lead_free.html
for more information about Diodes Incorporated’s definitions of Halogen- and Antimony-free, "Green"
and Lead-free.
3. Halogen- and Antimony-
free "Green” products are defined as those which contain <900ppm bromine, <900ppm chlorine (<1500ppm total Br + Cl) and
<1000ppm antimony compounds.
Typical Applications Circuit
AP65550
L1
1.5
μH
R1
8.25k
Ω
R2
22.1k
Ω
C5
0.1
µF
C2
44
μF
C1
20
μF
C4
8.2n
F
ON
OFF
8
IN
4
SS
1
EN
3
VREG5
6
SW
7
BST
2
FB
C3
1
µF
5
GND
INPUT
OUTPUT
V
OUT
1.05V
V
IN
12V
Figure 1. Typical Application Circuit