ACE726

ACE726
36V/1.5A Asynchronous Buck Converter
Description
The ACE726 is a high efficiency current‐mode asynchronous, 36V/1.5A buck converter. Its input voltage
ranges from 4V to 36V and it provides an adjustable regulated output voltage from 0.80V to 8V while
delivering up to 0.6A of output current.
The switching frequency is set to 650KHz, which works with a inductor as small as 10uH. And the
ACE726 will automatically switch between PFM and PWM mode based on the load current, thus to
enhance the converter efficiency at light load.
ACE726 consists of many protection blocks such as UVLO, input voltage over voltage protection to
stand much higher input voltage spike, thermal protection and output short circuit protection.
Features
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Adjustable Output Voltage, Vfb=0.80V
Output current is up to 1.5A @ Vin=24V
Range of operation input voltage: 4-36V
Input voltage UVLO: 3.7V (voltage decreasing)
Input Overvoltage Protection @38V
Withstand input voltage spike >42V
Operating current at zero load: 0.7mA (typ.)
Line regulation: 0.1%/V (typ.)
Load regulation: 10mV (typ.)
High efficiency, up to 90%
Environment Temperature: ‐20℃~85℃
Application
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Power Meter
Consumer Electronic Device for automobile
Security camera
Other 24V or wide range input voltage
Typical Application and PIN OUT
ACE726
VER 1.2
1
ACE726
36V/1.5A Asynchronous Buck Converter
Absolute Maximum Ratings
Parameter
Max
Input voltage
42V
Package Thermal Resistance
SOT-23-6 (ΘJC)
110℃/W
SOT-23-6 (ΘJA)
220℃/W
Operating Junction Temperature (TJ)
125℃
Ambient Temperature (TA)
-20℃ to 85℃
ESD (HBM)
>2000V
Storage Temperature (Ts)
-40℃ to 150℃
Note: Exceed these limits to damage to the device. Exposure to absolute maximum rating conditions may affect device reliability.
Packaging Type
SOT-23-6
6
5
4
1
2
3
SOT-23-6 Description
Function
1
BST
High side power transistor gate drive boost input
2
GND
Ground
3
FB
4
EN
5
VIN
6
SW
Feedback input with reference voltage set to 0.810V
Enable input. Setting it to high level or connecting to Vin via a resistor may turn
on the chip, while setting it to ground level will turn off the chip.
Power input, the input capacitor should be placed as close to VIN and GND pin
as possible
Power switching node to connect inductor
Ordering Information
ACE726 XX + H
Halogen - free
Pb - free
GM : SOT-23-6
VER 1.2
2
ACE726
36V/1.5A Asynchronous Buck Converter
Electrical Characteristics
Vout Vs. Iout at Vin=24V
Recommended work conditions
Parameter
Value
Input Voltage Range
6.5~36V
Output Voltage Range
0.8~8V
Operating Junction Temperature (TJ)
-20℃~125℃
Block Diagram
VER 1.2
3
ACE726
36V/1.5A Asynchronous Buck Converter
Electrical Characteristics(TA=25℃, VIN=12V, unless otherwise noted)
Parameter
Symbol
Conditions
Input Voltage Range
VIN
Output Voltage Range
VOUT
Feedback Voltage
Vref
Vin=12V, Ven=5V
UVLO Voltage
VUVLO
Vin H -->L,Iout=0.5A
Feedback Leakage current
Ifb
Quiescent Current
Iq
Line Regulation
Min
Max
Units
6.5
36
V
0.8
8
V
0.825
V
0.775
Typ
0.8
6
V
0.1
0.4
uA
Active, Vfb=1V, No Switching
0.6
1
mA
Shutdown, Vin=8V
6
10
uA
LnReg
Vin=5V to 12V
0.1
%/V
Load Regulation
LdReg
Iout=0.1 to 1.2A
0.02
%/A
Switching Frequency
Fsoc
Ven=3V, Vin=12V
High side Switch Rdson
RdsonH
Isw=200mA
Peak Inductor Current Limit
llimit
500
650
800
KHz
400
600
mohm
Vin=12-24V, Vout=3.3V
2
2.2
Vin=12-24V, Vout=5V
1.5
1.8
Vin=36V, Vout=3.3V-5V
1.0
1.1
0.8
1.1
A
EN High Threshold
Venh
1.5
V
EN Low Threshold
Venl
0.5
V
Input Over-Voltage Protection
Vovp
Ven=3V
38
V
Over Temperature Protection
TSD
Hystersis=40℃
150
℃
Typical Performance Characteristics
(Vin=24V, Vout=5.0V, L=10uH, Cin=10uF, Cout=22uF, TA=25℃, unless otherwise stated)
VER 1.2
4
ACE726
36V/1.5A Asynchronous Buck Converter
Typical Performance Characteristics
(Vin=24V, Vout=5.0V, L=10uH, Cin=10uF, Cout=22uF, TA=25℃, unless otherwise stated)
VER 1.2
5
ACE726
36V/1.5A Asynchronous Buck Converter
Typical Performance Characteristics
(Vin=24V, Vout=5.0V, L=10uH, Cin=10uF, Cout=22uF, TA=25℃, unless otherwise stated)
Functional Description
Loop Operation
The ACE726 is a wide input range, high‐efficiency, DC‐to‐DC step‐down switching regulator, capable of
delivering up to 0.6A of output current, integrated with a 400mΩ MOSFET, with external schottky diode. It
uses a PWM current‐mode control scheme. An error amplifier integrates error between the FB signal and
the internal reference voltage. The output of the integrator is then compared to the sum of a
current‐sense signal and the slope compensation ramp. This operation generates a PWM signal that
modulates the duty cycle of the power MOSFETs to achieve regulation for output voltage.
Current Limit
There is a cycle‐by‐cycle current limit on the high‐side MOSFET of 2.2A (typ.) when Vin <=24V. The
current limit linearly decreases when Vin increase above 24V, and finally becomes 1.2A (typ.) at Vin=36V.
When the current flowing out of SW exceeds this limit, the high‐side MOSFET turns off and the external
schottky diode rectifier turns on. Unlike the traditional method of current limiting by limiting the voltage at
the internal compensation node, which usually has large variation due to duty cycle variance, this type of
peak current limiting scheme provides a relatively more accurate limit for output current, thereby lowering
the requirements for system design.
Light Load Operation
Traditionally, a fixed current mode constant frequency PWM DC‐DC regulator always switches even
when the output load is small. When energy is shuffling back and forth through the power MOSFETs,
power is lost due to the finite RDSONs of the MOSFETs and parasitic capacitances. At light load, this loss
is prominent and efficiency is therefore very low. ACE726 employs a proprietary control scheme that
improves efficiency in this situation by enabling the device into a power save mode during light load,
thereby extending the range of high efficiency operation.
VER 1.2
6
ACE726
36V/1.5A Asynchronous Buck Converter
Component Selection
When setting up the ACE726 for different output voltage, please use following recommended component
value for the best performance.
VOUT(V)
COUT(uF)
L(uH)
8
22
15-22
5
22
10-15
3.3
22
6.8-10
Thermal Consideration
ACE726 is high efficiency Buck converter, which means it consumes very few power when converting
the high voltage to low voltage. However, when output power is very large, like 5V/1.5A, the output power
is as high as 7.5W, a heat dissipation path is strongly recommended to be routed on PCB. ACE726 is in
SOT23-6 package. The heat is conducted out via Pin 2 (GND), so the heat dissipation route on PCB
should be connected to the Pin 2 of the chip.
Packing Information
SOT-23-6
VER 1.2
7
ACE726
36V/1.5A Asynchronous Buck 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