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UNISONIC TECHNOLOGIES CO., LTD UC3655
Preliminary CMOS IC
500mA SYNCHRONOUS STEP-DOWN DC/DC CONVERTERS
4 5
DESCRIPTION
The UTC UC3655 is a synchronous-rectification type DC/DC converters with a built-in 0.6 P-channel driver transistor and 0.7 N-channel switching transistor, which designed to allow the use of ceramic capacitors. Using only a coil and two capacitors connected externally, the UC3655 enable a high efficiency, stable power supply with an output current of 500mA to be configured. Its operating voltage is 2.0V and the output voltage is programmable in a range from 0.9V to 4.0V in increments of 0.1V (accuracy: 2.0%) internally. The oscillation frequency is 1.2MHz. For operation mode, it is PWM control in the UTC UC3655, the UTC UC3655 series is automatic PWM/PFM switching control, allowing fast response, low ripple and high efficiency over the full range of load. Internal soft start and current control functions are built in it. All circuits are shutdown to reduce current consumption to as low as 1.0A or less during standby mode. With the built-in Under Voltage Lock Out (U.V.L.O.) function, when input voltage becomes 1.4V or lower the internal P channel driver transistor is forced OFF.
1 2 3
SOT-25
Lead-free: UC3655L Halogen-free: UC3655G
FEATURES
* Very high efficiency 92% * Low ripple rejection voltage 10mV * Output current 500mA @VIN=3.0V, VOUT=1.8V * Oscillation frequency is 1.2MHz * With PWM / PFM automatic switching control * Maximum duty ratio is 100% * Ceramic capacitor available
ORDERING INFORMATION
Normal UC3655-xx-AF5-R Ordering Number Lead Free UC3655L-xx-AF5-R Halogen Free UC3655G-xx-AF5-R Package SOT-25 Packing Tape Reel
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UC3655
MARKING
PACKAGE VOLTAGE CODE 12:1.2V 28:2.8V 33:3.3V 38:3.8V
Preliminary
CMOS IC
MARKING 321 UH XX 4 5
L: Lead Free L: Halogen Free
SOT-25
Voltage Code
PIN DESCRIPTION
PIN NO 1 2 3 4 5 PIN NAME VIN VSS CE / MODE VOUT Lx DESCRIPTION Power Input Voltage Ground Switch Pin For Chip Enable Mode Output Voltage Sense Pin Output Of Switching
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UC3655
BLOCK DIAGRAM
Phase Compensation
Preliminary
CMOS IC
VOUT
Current Limit & Feedback
P ch Driver Tr.
VIN
Vref with Soft Start, CE
Error Amp.
PWM Comparator
Logic
Buffer Driver
LX
N ch SW Tr.
PWM/PFM Selector
Ramp Wave Generator, OSC
U.V.L.O Comp. U.V.L.O.
CE/MODE Control Logic
CE/ MODE VSS
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UC3655
PARAMETER VIN Pin Voltage
Preliminary
CMOS IC
ABSOLUTE MAXIMUM RATING (Ta=25)
SYMBOL RATINGS UNIT VIN - 0.3 ~ 6.5 V LX VLx - 0.3 ~ VIN + 0.3 Input/Output Pins VOUT VOUT -0.3 ~ 6.5 V CE/MODE VCE - 0.3 ~ VIN + 0.3 Lx Pin Current ILx 1000 mA Power Dissipation PD 250 mW Operating Temperature TOPR - 40 ~ 85 Storage Temperature Range TSTG - 55 ~ 125 Note: Absolute maximum ratings are those values beyond which the device could be permanently damaged. Absolute maximum ratings are stress ratings only and functional device operation is not implied.
ELECTRICAL CHARACTERISTICS (fOSC=1.2MHz, Ta=25)
UC3655-12 (VIN=3.6V, VOUT=1.2V) PARAMETER SYMBOL Operating Voltage Range VIN Output Voltage VOUT U.V.L.O. Voltage VUVLO VOUT Output Voltage Temperature VOUT*TOPR Characteristics Maximum Output Current IOUT(MAX) Supply Current IDD ISTN-BY Stand-by Current PFM Switch Current IPFM Current Limit ILIM Efficiency (Note 1) OSCILLATOR Oscillation Frequency fOSC Maximum Duty Ratio DMAX Minimum Duty Ratio DMIN Soft-Start Time TSS Latch Time Tlat CE (PIN 3) CE "H" Voltage VCEH CE "L" Voltage VCEL CE "H" Current ICEH CE "L" Current ICEL LX (PIN 5) LX SW "H" ON Resistance RLXH LX SW "L" ON Resistance RLXL LX SW "H" Leak Current LX SW "L" Leak Current ILEAKH ILEAKL TEST CONDITIONS CE=VIN, IOUT=30mA CE=VIN, VOUT=0V, LX=L IOUT=30mA, -40TOPR85 VIN=4.5V VIN=CE=5.0V, VOUT=VOUT*1.1 VIN=5.0V, CE=0V, VOUT=VOUT*1.1 CE=VIN, IOUT=1mA VIN=CE=5.0V, VOUT=0V CE=VIN=4.5V, IOUT=100mA IOUT=100mA CE=VIN, VOUT=0V CE=VOUT=VIN IOUT=1mA VIN=CE=5.0V (Note 3) 500 70 0 140 700 90 1200 115 1.0 180 MIN 2.0 1.176 1.0 TYP 1.200 1.40 100 MAX 6.0 1.224 1.78 UNIT V V V ppm/ mA A A mA mA % kHz % % ms ms V V A A 1.0 1.0 MAX 6.0 2.856 1.78 A A UNIT V V V ppm/ 120 mA A
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100 600
1020 100 0.5 1 0.9 VSS -0.1 -0.1
1380 0 3.0 20 VIN 0.3 0.1 0.1
1.0
VIN=CE=5.5V, VOUT=0V VIN=5.5V, CE=0V, VOUT=0V CE=0.5VIN, VOUT=0V, ILX=100mA CE=0.5VIN, ILX=100mA VIN=VOUT=5.0V, CE=0V, LX=0V (Note 2) VIN=VOUT=5.0V, CE=0V, LX=5.0V TEST CONDITIONS CE=VIN, IOUT=30mA CE=VIN, VOUT=0V, LX=L IOUT=30mA, -40TOPR85 VIN=4.5V VIN=CE=5.0V, VOUT=VOUT*1.1
0.6 0.7 0.01 0.01 MIN 2.0 2.744 1.0 TYP 2.8 1.40 100 500 75
UC3655-28 (VIN=3.6V, VOUT=2.8V) PARAMETER SYMBOL Operating Voltage Range VIN Output Voltage VOUT U.V.L.O. Voltage VUVLO VOUT Output Voltage Temperature VOUT*TOPR Characteristics Maximum Output Current IOUT(MAX) Supply Current IDD www.unisonic.com.tw
UNISONIC TECHNOLOGIES CO., LTD
UC3655
PARAMETER Stand-by Current PFM Switch Current Current Limit Efficiency (Note 1) OSCILLATOR Oscillation Frequency Maximum Duty Ratio Minimum Duty Ratio Soft-Start Time Latch Time CE (PIN 3) CE "H" Voltage CE "L" Voltage CE "H" Current CE "L" Current LX (PIN 5) LX SW "H" ON Resistance LX SW "L" ON Resistance LX SW "H" Leak Current LX SW "L" Leak Current SYMBOL ISTN-BY IPFM ILIM fOSC DMAX DMIN TSS Tlat VCEH VCEL ICEH ICEL RLXH RLXL ILEAKH ILEAKL
Preliminary
TEST CONDITIONS VIN=5.0V, CE=0V, VOUT=VOUT*1.1 CE=VIN, IOUT=1mA VIN=CE=5.0V, VOUT=0V CE=VIN=4.5V, IOUT=100mA IOUT=100mA CE=VIN, VOUT=0V CE=VOUT=VIN IOUT=1mA VIN=CE=5.0V (Note 3) MIN 100 600 TYP 0 140 700 92 1200
CMOS IC
MAX 1.0 180 UNIT A mA mA % kHz % % ms ms V V A A 1.0 1.0 MAX 6.0 3.366 1.78 A A UNIT V V V ppm/ 120 1.0 180 mA A A mA mA % kHz % % ms ms V V A A 1.0 1.0 A A
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ELECTRICAL CHARACTERISTICS(Cont.)
1020 100 0.5 1 0.9 VSS -0.1 -0.1
1380 0 3.0 20 VIN 0.3 0.1 0.1
1.0
VIN=CE=5.5V, VOUT=0V VIN=5.5V, CE=0V, VOUT=0V CE=0.5VIN, VOUT=0V, ILX=100mA CE=0.5VIN, ILX=100mA VIN=VOUT=5.0V, CE=0V, LX=0V (Note 2) VIN=VOUT=5.0V, CE=0V, LX=5.0V TEST CONDITIONS CE=VIN, IOUT=30mA CE=VIN, VOUT=0V, LX=L IOUT=30mA, -40TOPR85 VIN=4.5V VIN=CE=5.0V, VOUT=VOUT*1.1 VIN=5.0V, CE=0V, VOUT=VOUT*1.1 CE=VIN, IOUT=1mA VIN=CE=5.0V, VOUT=0V CE=VIN=4.5V, IOUT=100mA IOUT=100mA CE=VIN, VOUT=0V CE=VOUT=VIN IOUT=1mA VIN=CE=5.0V (Note 3)
0.5 0.6 0.01 0.01 MIN 2.0 3.234 1.0 TYP 3.300 1.40 100 500 75 0 140 700 92 1200
UC3655-33 (VIN=5.0V, VOUT=3.3V) PARAMETER SYMBOL Operating Voltage Range VIN Output Voltage VOUT U.V.L.O. Voltage VUVLO VOUT Output Voltage Temperature VOUT*TOPR Characteristics Maximum Output Current IOUT(MAX) Supply Current IDD ISTN-BY Stand-by Current PFM Switch Current IPFM Current Limit ILIM Efficiency (Note 1) OSCILLATOR Oscillation Frequency fOSC Maximum Duty Ratio DMAX Minimum Duty Ratio DMIN Soft-Start Time TSS Latch Time Tlat CE (PIN 3) CE "H" Voltage VCEH CE "L" Voltage VCEL CE "H" Current ICEH CE "L" Current ICEL LX (PIN 5) LX SW "H" ON Resistance RLXH LX SW "L" ON Resistance RLXL LX SW "H" Leak Current LX SW "L" Leak Current ILEAKH ILEAKL
100 600
1020 100 0.5 1 0.9 VSS -0.1 -0.1
1380 0 3.0 20 VIN 0.3 0.1 0.1
1.0
VIN=CE=5.5V, VOUT=0V VIN=5.5V, CE=0V, VOUT=0V CE=0.50VIN, VOUT=0V, ILX=100mA CE=0.5VIN, ILX=100mA VIN=VOUT=5.0V, CE=0V, LX=0V (Note 2) VIN=VOUT=5.0V, CE=0V, LX=5.0V
0.5 0.6 0.01 0.01
UNISONIC TECHNOLOGIES CO., LTD
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UC3655
UC3655-38 (VIN=5.0V, VOUT=3.8V) PARAMETER SYMBOL Operating Voltage Range VIN Output Voltage VOUT U.V.L.O. Voltage VUVLO VOUT Output Voltage Temperature VOUT*TOPR Characteristics Maximum Output Current IOUT(MAX) Supply Current IDD ISTN-BY Stand-by Current PFM Switch Current IPFM Current Limit ILIM Efficiency (Note 1) OSCILLATOR Oscillation Frequency fOSC Maximum Duty Ratio DMAX Minimum Duty Ratio DMIN Soft-Start Time TSS Latch Time Tlat CE (PIN 3) CE "H" Voltage VCEH CE "L" Voltage VCEL CE "H" Current ICEH CE "L" Current ICEL LX (PIN 5) LX SW "H" ON Resistance RLXH LX SW "L" ON Resistance RLXL LX SW "H" Leak Current ILEAKH
Preliminary
CMOS IC
ELECTRICAL CHARACTERISTICS(Cont.)
TEST CONDITIONS CE=VIN, IOUT=30mA CE=VIN, VOUT=0V, LX=L IOUT=30mA, -40TOPR85 VIN=4.5V VIN=CE=5.0V, VOUT=VOUT*1.1 VIN=5.0V, CE=0V, VOUT=VOUT*1.1 CE=VIN, IOUT=1mA VIN=CE=5.0V, VOUT=0V CE=VIN=4.5V, IOUT=100mA IOUT=100mA CE=VIN, VOUT=0V CE=VOUT=VIN IOUT=1mA VIN=CE=5.0V (Note 3) 500 75 0 140 700 92 1200 120 1.0 180 MIN 2.0 3.724 1.0 TYP 3.800 1.40 100 MAX 6.0 3.876 1.78 UNIT V V V ppm/ mA A A mA mA % kHz % % ms ms V V A A 1.0 A
100 600
1020 100 0.5 1 0.9 VSS -0.1 -0.1
1380 0 3.0 20 VIN 0.3 0.1 0.1
1.0
VIN=CE=5.5V, VOUT=0V VIN=5.5V, CE=0V, VOUT=0V CE=0.5VIN, VOUT=0V, ILX=100mA CE=0.5VIN, ILX=100mA VIN=VOUT=5.0V, CE=0V, LX=0V (Note 2) VIN=VOUT=5.0V, CE=0V, LX=5.0V
0.5 0.6 0.01
LX SW "L" Leak Current ILEAKL 0.01 1.0 A Note: 1. = [(VOUT*IOUT)/(VIN*IIN)]*100 Note: 2. When temperature is high, a current of approximately 20A (maximum) may leak. Note: 3. Time until it short-circuits DCOUT with GND through 1 of resistance from a state of operation and is set to DCOUT=0V from current limit pulse generating.
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UC3655
OPERATIONAL EXPLANATION
Preliminary
CMOS IC
CE / MODE Pin Function When a low level signal is input to the CE/MODE pin the operation of the UC3655 series will enter into the shut down mode. In this mode, the current consumption occurs only in the detector and is 0 A (TYP.), with a state of high impedance at the Lx pin and VOUT pin. By inputting a high level signal to the CE/MODE pin the IC starts its operation. The input of the CE/MODE pin is a CMOS input and its sink current is 0 A (TYP.). UC3655 series - Examples of how to use CE/MODE pin VDD R1 CE/MODE VIN SW_CE ON OFF STATUS Stand-by Operation
SW_CE
SW_CE ON OFF
STATUS Stand-by Operation
FUNCTIONS
CE/MODE H Level M Level L Level VOLTAGE LEVEL VIN-0.3VH levelVIN 0.9VM LevelVIN-1.0V 0VL Level0.3V OPERATION Synchronous PWM/PFM Automatic Switching Control Stand-by
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UC3655
TEST CIRCUIT
Preliminary
CMOS IC
CI CL L
4.7F (Ceramic) 10F (Ceramic) 3.3H
UNISONIC TECHNOLOGIES CO., LTD
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UC3655
TYPICAL APPLICATION CIRCUIT
Preliminary
CMOS IC
VIN CI CE/MODE
VIN CE/ MODE VSS
LX VOUT
L
VOUT (400mA) CL
CI CL L
4.7F (Ceramic) 10F (Ceramic) 3.3H
UTC assumes no responsibility for equipment failures that result from using products at values that exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or other parameters) listed in products specifications of any and all UTC products described or contained herein. UTC products are not designed for use in life support appliances, devices or systems where malfunction of these products can be reasonably expected to result in personal injury. Reproduction in whole or in part is prohibited without the prior written consent of the copyright owner. The information presented in this document does not form part of any quotation or contract, is believed to be accurate and reliable and may be changed without notice.
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www.unisonic.com.tw
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