Document
AME
AME5287
3A, 300KHz ~ 2MHz Synchronous Rectified Step-Down Converter
n General Description
The AME5287 is a Synchronous Rectified Step-Down Converter with internal power MOSFETs. It achieves 3A continuous output current over a wide switching frequency range with excellent load and line regulation.
Current mode operation provides fast transient response and eases of loop stabilization. Internal soft-start minimizes the inrush supply current at startup. The circuit protection includes cycle-by-cycle current limiting, output short circuit frequency protection and thermal shutdown. In shutdown mode, the regulator reduces the current less than 1µA of supply current.
This device is available in SOP-8/PP ,DFN-8 package with exposed pad for low thermal resistance.
n Typical Application
L VIN 2.2µH 5V
IN SW
CIN 10µF
C2 Optional
EN OFF ON AME5287
C1 680pF
R3 25KΩ
COMP GND
FB
FREQ RFREQ 18KΩ
R1 75KΩ
R2 24KΩ
VOUT 3.3V
COUT 22µF
Figure 1. 3.3V at 3A Step-Down Regulators.
n Features
l 3A Output Current l Stable with Low ESR Output Ceramic
Capacitors l Pre-Regulator for Linear Regulators l Up to 95% Efficiency l Less than 1µA Shutdown Current l Wide Switching Frequency Range from
300KHz~2MHz l Thermal Protection l Cycle-by-Cycle Over Current Protection l Output Adjustable from 0.8V to VIN l Short Circuit Protection l Green Products Meet RoHS Standards
VIN 3V~5V
CIN 10µF
C2 Optional
L 1.5µH
IN SW
EN
OFF ON
AME5287
R1 6KΩ
C1 680pF
R3 8.2KΩ
COMP
FB
GND
FREQ
RFREQ 18KΩ
R2 24KΩ
VOUT 1V
COUT 22µF
Figure 2. 1V at 3A Step-Down Regulators.
n Applications
l TV l Distributed Power Systems l Pre-Regulator for Linear Regulators l Digital Cameras
Rev. A.01
1
AME
AME5287 n Functional Block Diagram
3A, 300KHz ~ 2MHz Synchronous Rectified Step-Down Converter
EN
ENABLE
UVLO
CURRENT SENSE
CURRENT LIMIT
IN
FREQ
OSC
COMP GND FB
0.8V VREF
EA
+
SLOPE
SOFT START
+
+
-
PWM
Short circuit
OTP
LOGIC
DRIVER
IRCMP
+
SW SW
PGND
n Pin Configuration
SOP-8/PP Top View
8 7 65
AME5287 9
1 2 34
AME5287-AZAADJ 1. COMP 2. GND 3. EN 4. IN 5. SW 6. SW 7. FREQ 8. FB 9. GND (Exposed Pad)
* Die Attach: Conductive Epoxy
DFN-8C (3mmx3mmx0.75mm)
Top View
87 65
AME5287 9
12 34
AME5287-AVAADJ 1. COMP 2. GND 3. EN 4. IN 5. SW 6. SW 7. FREQ 8. FB 9. GND (Exposed Pad)
* Die Attach: Conductive Epoxy
Note. Connect exposed pad (heat sink on the back) to GND. 2
Rev. A.01
AME
AME5287
3A, 300KHz ~ 2MHz Synchronous Rectified Step-Down Converter
n Pin Description
Pin No. Pin Name
1 COMP 2 GND
Pin Description
Compensation Node. COMP is used to compensate the regulation control loop. Connect a series RC network from COMP to GND to compensate the regulation control loop. In some cases, an additional capacitor from COMP to GND is required.
Ground. Connect the exposed pad to GND.
3 EN Enable. Pull EN below 0.4V to shut down the regulator.
Power Input. IN supplies the power to the IC, as well as the step-down converter 4 IN switches. Bypass IN to GND with a.