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ACE721A
Technology Description
1.2MHz, 800mA SYNCHRONOUS DC-DC BUCK CONVERTER
The ACE721A is a 1.2MHz fixed frequency, current mode, PWM synchronous buck (step-down) DC-DC converter, capable of driving a 800mA load with high efficiency, excellent line and load regulation. The device integrates a main switch and a synchronous switch without an external Schottky diode. It is ideal for powering portable equipment that runs from a single Li-ion battery. A standard series of inductors are available from several different manufactures optimized for use with the ACE721A. This feature greatly simplifies the design of switch-mode power supplies. This IC is available in SOT-23-5 packages.
Features
* * * * * * * * * * * * * *
High Efficiency: up to 95% Output Current: 800mA Input Voltage Range: 2.5V to 5.5V Fixed 1.2MHz Frequency Current Mode Control 100% Duty Cycle in Dropout Built-in Short Circuit Protection Built-in Thermal Shutdown Function Built-in Current Limit Function Shutdown Current: <1A
Application
GPS WiFi Card Portable Media Player Digital Still and Video Cameras
Absolute Maximum Ratings
Parameter Input Voltage Feedback Voltage EN Pin Voltage SW Pin Voltage Thermal Resistance Operating Junction Temperature Storage Temperature Symbol VIN VFB VEN VSW JA TJ TSTG Value -0.3 to 6 -0.3 to VIN+0.3 -0.3 to VIN+0.3 -0.3 to VIN+0.3 SOT-23-5 125 -65 to 150 250 Unit V V V V /W
VER 1.3
1

ACE721A
Technology
1.2MHz, 800mA SYNCHRONOUS DC-DC BUCK CONVERTER
Note 1: Stresses greater than those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress rating only, and functional operation of the device at these or any other conditions beyond those indicated under "Recommended Operating Conditions" is not implied. Exposure to "Absolute Maximum Ratings" for extended periods may affect device reliability.
Packaging Type
5 4
1
2
3
Pin SOT-23-5 1 EN 2 GND 3 SW 4 VIN 5 FB
Ordering information
Selection Guide ACE721A XX XX + H Halogen - free Pb - free BN : SOT-23-5 ADJ: Adjustable Voltage
Functional Block Diagram
VER 1.3
2

ACE721A
Technology Recommended Work Conditions
1.2MHz, 800mA SYNCHRONOUS DC-DC BUCK CONVERTER
Item Min Typ Max Unit Input Voltage (VIN) 2.5 5.5 V Maximum Output Current (IOUT(MAX)) 800 mA Operating Ambient Temperature (TA) -40 85
Electrical Characteristics
VIN=VEN=3.6V, TA=25, unless otherwise specified. Specifications with boldface type apply over full operating temperature range from -40 to 85 Parameter Supply Current Shutdown Supply Current Under Voltage Lockout Threshold Under Voltage Lockout Hysteresis Feedback Bias Current Feedback Voltage Symbol ICC ISHDN VUVLO VHUVLO IFB VFB VFB=0.65V IOUT=100mA VIN=2.5V, VOUT=0.9V Maximum Output Current Switch Current Limit Oscillator Frequency EN Pin Threshold EN Pin Input Leakage Current Internal PFET On Resistance Internal NFET On Resistance Maximum Duty Cycle Soft-start Time Thermal Shutdown Threshold Thermal Shutdown Hysteresis IOUT(MAX) ILIM fOSC VENL VENH IH IL RDSONP RDSONN DMAX TSS TOTSD THYS VEN=3.6V VEN=0V ISW=100mA ISW=-100mA VFB=0.55V VEN=0V to VIN IOUT=50mA 1.5 -0.1 -0.1 0.44 0.29 100 220 160 30 0.1 0.1 VIN=3.6V, VOUT=1.2V VIN=4.6V, VOUT=3.3V VFB=0.55V -50 0.588 / 0.582 800 800 800 0.85 0.8 1.15 1.2 1.4 0.6 A MHz V A % S mA Conditions VFB=0.55V VEN=0V, VIN=5.5V Rising edge Min. Typ. 400 0.01 2.27 200 0.5 0.600 50 0.612 / 0.618 Max. 600 1 Unit A A V mV nA V
VER 1.3
3

ACE721A
Technology Typical Application Circuit
150K R2 EN FB VIN SW ACE721A-ADJ GND 300K R1
1.2MHz, 800mA SYNCHRONOUS DC-DC BUCK CONVERTER
Vin 2.5V to 5.5V
Cin 10uF
L 10uH
Vout 1.8V
Cout 10uF
800mA
Typical Performance Characteristics
L=10H, COUT=10F, TA=25, unless otherwise noted.
Input Voltage (V)
Temperature ()
Figure 1. Frequency vs. Input Voltage
Figure 2. Supply Current vs. Temperature
Temperature ()
Output Current (mA)
Figure 3. Current Limit vs. Temperature
Figure 4. Output Voltage vs. Output Current
VER 1.3
4

ACE721A
Technology
1.2MHz, 800mA SYNCHRONOUS DC-DC BUCK CONVERTER
400ns/div
400ns/div
Figure 5. Light Load Operation (VIN=3.6V, VOUT=1.8V, IOUT=0mA)
Figure 6. Heavy Load Operation (VIN=3.6V, VOUT=1.8V, IOUT=800mA)
200s/div
400s/div
Figure 7. Load Transient (VIN=3.6V, VOUT=1.8V, IOUT=0mA to 800mA)
Figure 8. Start up from Shutdown (VIN=3.6V, VOUT=1.8V, RLOAD=2.5)
10s/div
40s/div
Figure 9. Short Circuit Protection (VIN=3.6V, VOUT=1.8V, no load)
Figure 10. Short Circuit Recovery (VIN=3.6V, VOUT=1.8V, no load)
VER 1.3
5

ACE721A
Technology
1.2MHz, 800mA SYNCHRONOUS DC-DC BUCK CONVERTER
Output Current (mA)
Output Current (mA)
Figure 11. Efficiency vs. Output Current
Figure 12. Efficiency vs Output Current
Temperature ()
Figure 13. Normalized Feedback Voltage vs. Temperature
VER 1.3
6

ACE721A
Technology Packing Information
SOT-23-5
1.2MHz, 800mA SYNCHRONOUS DC-DC BUCK CONVERTER
VER 1.3
7

ACE721A
Technology
1.2MHz, 800mA SYNCHRONOUS DC-DC 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 1.3
8

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