ACE ACE721B 1.3a 1.4mhz synchronous step-down converter Datasheet

ACE721B
1.3A 1.4MHz Synchronous Step-Down Converter
Description
The ACE721B series are a high efficiency monolithic synchronous buck regulator using a constant
frequency, current mode architecture. The device is available in an adjustable version. Supply current
during operation is only 40μA and drops to ≤ 1μA in shutdown. The 2.5V to 5.5V input voltage range
makes the ACE721B ideally suited for single Li-Ion battery-powered applications. 100% duty cycle
provides low dropout operation, extending battery life in portable systems. Automatic Burst Mode
operation increases efficiency at light loads, further extending battery life.
Switching frequency is internally set at 1.4MHz, allowing the use of small surface mount inductors and
capacitors.
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.
Features
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High Efficiency: Up to 95%
Very Low Quiescent Current: 40μA
1.3A Output Current
2.5V to 5.5V Input Voltage Range
1.4MHz Constant Frequency Operation
No Schottky Diode Required
Low Dropout Operation: 100% Duty Cycle
0.6V Reference Allows Low Output Voltages
Shutdown Mode Draws < 1μA Supply Current
Current Mode Operation for Excellent Line and Load Transient Response
Over temperature Protected
Application
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Mobile Phones
Personal Information Appliances
Wireless and DSL Modems
Digital Still Cameras
MP3 Players
Portable Instruments
VER 1.2
1
ACE721B
1.3A 1.4MHz Synchronous Step-Down Converter
Absolute Maximum Ratings
Parameter
Symbol
Value
Unit
Supply Voltage
VIN
-0.3 to 6
V
EN, VFB Voltages
VEN
-0.3 to VIN
V
SW Voltage
VSW
-0.3 to VIN+0.3
V
Peak SW Sink and Source Current
IPK
3
A
Power Dissipation TA=25℃
PD
0.606
W
Operation Temperature
TOPR
-40 to 85
℃
Storage Temperature Range
TSTG
-65 to 150
℃
Packaging Type
DFN2*2-6L
(TOP VIEW)
DFN2*2-6L Description
1
GND
2
EN
3
VIN
4
SW
5
GND
6
FB/VOUT
7
EP
Function
Ground pin
Chip Enable Pin. Drive EN above 1.5V to turn on the part. Drive RUN below
0.3V to turn it off. Do not leave RUN floating.
Supply input pin.
Power Switch Output. It is the switch node connection to Inductor.This pin
connects to the drains of the internal P-ch and N-ch MOSFET switches.
Ground pin
Adjustable version feedback input. Connect FB to the center point of the
external resistor divider. The feedback threshold voltage is 0.6V.
Power Ground exposed pad, Must be connected to bare copper ground
plane
VER 1.2
2
ACE721B
1.3A 1.4MHz Synchronous Step-Down Converter
Ordering information
ACE721B XX XX + H
Halogen - free
Pb - free
MN : DFN2*2-6L
ADJ: Adjustable Voltage/1.2V/1.5V/1.8V
Functional Block Diagram
VER 1.2
3
ACE721B
1.3A 1.4MHz Synchronous Step-Down Converter
Electrical Characteristics
VIN=3.6V, TA=25℃, VOUT=1.8V, L=2.2µH, COUT=10µF, unless otherwise specified.
Symbol
Parameter
Conditions
VIN
Input Voltage Range
Min
Typ
2.5
Max
Unit
5.5
V
Input DC Supply Current
IS
PWM Mode
Vout = 90%, Iload=0mA
PFM Mode
Vout = 105%, Iload=0mA
Shutdown Mode
VRUN = 0V, VIN=4.2V
TA = 25°C
TA = 0°C ≤ TA ≤ 85°C
TA = -40°C ≤TA ≤ 85°C
VFB
Regulated Feedback Voltage
ΔVOUT
Reference Voltage Line
Regulation
VLOADREG
Output Voltage Load
Regulation
VVOLTAGEREG
Output Voltage Accuracy
FOSC
Oscillation Frequency
RPFET
On Resistance of PMOS
Vout=0V
ISW=100mA
RNFET
On Resistance of NMOS
IPK
Peak Current Limit
VIH
*
VIN =2.5V to 5.5V
VIN = 2.5V to 5.5V,
Iout=10mA to 1300mA
Iout=10mA to 1300mA
EN Leakage Current
ILSW
SW Leakage Current
300
75
1.0
0.6
0.6
0.6
0.612
0.613
0.615
0.1
-3
Vout=100%
µA
V
%/V
3
%Vo
ut
0.2
%/A
1.4
300
MHz
KHz
150
200
mΩ
ISW=-100mA
120
180
mΩ
VIN = 3V, Vout=90%
2.6
EN Threshold
IEN
0.588
0.586
0.585
150
35
0.1
0.3
VRUN=0V,VIN=Vsw=5V
A
1
1.5
V
±0.01
±1
µA
±0.01
±1
µA
*:If need to use the EN pin close output, please make sure the EN level is lower than 0.3V.
Typical Application Circuit
ACE721B
VER 1.2
4
ACE721B
1.3A 1.4MHz Synchronous Step-Down Converter
With R2 = 300kΩ to 60kΩ so the IR2 = 2μA to 10μA, and (R1 x C1) should be in the range between 3x10-6
and 6x10-6 for component selection.
PCB Layout Checklist
When laying out the printed circuit board, the following checklist should be used to ensure proper
operation of the ACE721B. Check the following in your layout:
1. The power traces, consisting of the GND trace, the SW trace and the V IN trace should be kept short,
direct and wide.
2. Does the VFB pin connect directly to the feedback resistors, The resistive divider R1/R2 must be
connected between the ( + ) plate of COUT and ground.
3. Does the ( + ) plate of CIN connect to VIN as closely as possible, This capacitor provides the AC
current to the internal power MOSFETS.
4. Keep the switching node, SW, away from the sensitive VFB node.
5. Keep the ( – ) plates of CIN and COUT as close as possible.
Typical Performance Characteristics
VER 1.2
5
ACE721B
1.3A 1.4MHz Synchronous Step-Down Converter
Typical Performance Characteristics
VER 1.2
6
ACE721B
1.3A 1.4MHz Synchronous Step-Down Converter
Packing Information
DFN2*2-6L
VER 1.2
7
ACE721B
1.3A 1.4MHz Synchronous Step-Down Converter
Notes
ACE does not assume any responsibility for use as critical components in life support devices or systems
without the express written approval of the president and general counsel of ACE Electronics Co., LTD.
As sued herein:
1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant
into the body, or (b) support or sustain life, and shoes failure to perform when properly used in
accordance with instructions for use provided in the labeling, can be reasonably expected to result in
a significant injury to the user.
2. A critical component is any component of a life support device or system whose failure to perform can
be reasonably expected to cause the failure of the life support device or system, or to affect its safety
or effectiveness.
ACE Technology Co., LTD.
http://www.ace-ele.com/
VER 1.2
8
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