Datasheet

UNISONIC TECHNOLOGIES CO., LTD
UC3500
CMOS IC
HIGH EFFICIENCY VFM
CONTROLLED STEP-UP
DC/DC CONVERTER

DESCRIPTION
The UTC UC3500 Step-up DC/DC converters are optimized
for applications that prioritize high efficiency and high frequency.
The efficiency is greatly improved by utilizing an internal VFM
controlled scheme that switches with fixed frequency and is
adjustable up to more than 150 KHz depending on the load.
The UTC UC3500 requires only three external components
to realize the conversion from the battery voltage to the selected
output voltage in the range of 2.5V ~ 5.5V.
The start-up voltage of UTC UC3500 is guaranteed at 0.8V
and the device is operating down to 0.5V. The Output current is
guaranteed up to 150mA, while quiescent current is only 18μA.

FEATURES
* 0.8V start-up voltage
* 0.5V hold-on voltage
* Output current up to 150mA
* Low supply current of 18μA
* Wide output voltage range of 2.5V~5.5V
* High efficiency up to 88%
* Low profile and minimum external components

ORDERING INFORMATION
Ordering Number
UC3500G-xx-AB3-R
UC3500G-xx-AE3-R
UC3500G-xx-AF5-R
www.unisonic.com.tw
Copyright © 2015 Unisonic Technologies Co., Ltd
Package
SOT-89
SOT-23
SOT-25
Packing
Tape Reel
Tape Reel
Tape Reel
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UC3500

CMOS IC
MARKING INFORMATION
PACKAGE
VOLTAGE CODE
5
SOT-25
Voltage Code
25:2.5V
27:2.7V
28:2.8V
30:3.0V
33:3.3V
36:3.6V
40:4.0V
50:5.0V
SOT-23
MARKING
4
U3XXG
1
2
3
3
Voltage Code
U3XXG
2
1
SOT-89

PIN CONFIGURATION
NC
NC
5
4
1
LX
2
3
GND OUT
SOT-25

SOT-23
SOT-89
BLOCK DIAGRAM
OUT
OUT
LX
OSCILLATOR
ERROR
AMPLIFIER
VFM
CONTROL
VREF
VIX LIMITER
GND
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2 of 10
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UC3500

CMOS IC
ABSOLUTE MAXIMUM RATING
PARAMETER
SYMBOL
RATINGS
UNIT
Output Voltage
VOUT
7
V
Input Voltage
VIN
7
V
LX Pin Voltage
VLX
7
V
LX Pin Output Current
ILX
Internally limited
SOT-23/SOT-25
160
Power Dissipation at 25°С
mW
SOT-89
500
PD
SOT-23/SOT-25
1.6
Derating Rate TA>25°С
°С/mW
SOT-89
5
Operating Temperature
TOPR
-25 ~ +85
°С
Storage Temperature
TSTG
-65 ~ +150
°С
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 (TA = 25°С, unless otherwise specified.)
UC3500-2.5V (VIN = 1.4V)
PARAMETER
Output Voltage
SYMBOL
VOUT
Start-up Voltage (VIN-VF) (Note)
VSTART
Hold-on Voltage
VHOLD
Supply Current
Internal Switch RDS(ON)
Internal Leakage Current
Maximum Oscillator Frequency
Oscillator Duty Cycle
Efficiency
ISUPPLY
RLX
ILX(LEAK)
fOSC
Dty
η
UC3500-2.7V (VIN = 1.6V)
PARAMETER
Output Voltage
SYMBOL
VOUT
Start-up Voltage (VIN-VF) (Note)
VSTART
Hold-on Voltage
VHOLD
Supply Current
Internal Switch RDS(ON)
Internal Leakage Current
Maximum Oscillator Frequency
Oscillator Duty Cycle
Efficiency
ISUPPLY
RLX
ILX(LEAK)
fOSC
Dty
η
TEST CONDITIONS
IOUT = 10mA
IOUT = 0
IOUT = 1mA
IOUT = 0
IOUT = 1mA
IOUT = 0
ILX = 100mA
VLX = 4V, VOUT = 2.8V
IOUT = 10mA
to be measure on LX pin
IOUT = 10mA
IOUT = 50mA
IOUT = 100mA
TEST CONDITIONS
IOUT = 10mA
IOUT = 0
IOUT = 1mA
IOUT = 0
IOUT = 1mA
IOUT = 0
ILX = 100mA
VLX = 4V, VOUT = 3.0V
IOUT = 10mA
to be measure on LX pin
IOUT = 10mA
IOUT = 50mA
IOUT = 100mA
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
MIN
2.4
0.4
0.25
MIN
2.6
0.4
0.25
TYP
2.5
0.7
0.8
0.6
0.5
18
760
0.1
150
75
81
83
82
MAX
2.6
1.1
1.2
TYP
2.7
0.7
0.8
0.6
0.5
18
760
0.1
150
75
82
83
82
MAX
2.8
1.1
1.2
0.3
0.3
UNIT
V
V
V
V
V
µA
mΩ
µA
KHz
%
%
%
%
UNIT
V
V
V
V
V
µA
mΩ
µA
KHz
%
%
%
%
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UC3500

CMOS IC
ELECTRICAL CHARACTERISTICS(Cont.)
UC3500-2.8V (VIN = 1.7V)
PARAMETER
Output Voltage
SYMBOL
VOUT
Start-up Voltage (VIN-VF) (Note)
VSTART
Hold-on Voltage
VHOLD
Supply Current
Internal Switch RDS(ON)
Internal Leakage Current
Maximum Oscillator Frequency
Oscillator Duty Cycle
Efficiency
ISUPPLY
RLX
ILX(LEAK)
fOSC
Dty
η
UC3500-3.0V (VIN = 1.8V)
PARAMETER
Output Voltage
SYMBOL
VOUT
Start-up Voltage (VIN-VF) (Note)
VSTART
Hold-on Voltage
VHOLD
Supply Current
Internal Switch RDS(ON)
Internal Leakage Current
Maximum Oscillator Frequency
Oscillator Duty Cycle
Efficiency
ISUPPLY
RLX
ILX(LEAK)
fOSC
Dty
η
UC3500-3.3V (VIN = 2.0V)
PARAMETER
Output Voltage
SYMBOL
VOUT
Start-up Voltage (VIN-VF) (Note)
VSTART
Hold-on Voltage
VHOLD
Supply Current
Internal Switch RDS(ON)
Internal Leakage Current
Maximum Oscillator Frequency
Oscillator Duty Cycle
Efficiency
ISUPPLY
RLX
ILX(LEAK)
fOSC
Dty
η
TEST CONDITIONS
IOUT = 10mA
IOUT = 0
IOUT = 1mA
IOUT = 0
IOUT = 1mA
IOUT = 0
ILX = 100mA
VLX = 4V, VOUT = 3.1V
IOUT = 10mA
to be measure on LX pin
IOUT = 10mA
IOUT = 50mA
IOUT = 100mA
TEST CONDITIONS
IOUT = 10mA
IOUT = 0
IOUT = 1mA
IOUT = 0
IOUT = 1mA
IOUT = 0
ILX = 100mA
VLX = 4V, VOUT = 3.3V
IOUT = 10mA
to be measure on LX pin
IOUT = 10mA
IOUT = 50mA
IOUT = 100mA
TEST CONDITIONS
IOUT = 10mA
IOUT = 0
IOUT = 1mA
IOUT = 0
IOUT = 1mA
IOUT = 0
ILX = 100mA
VLX = 4V, VOUT = 3.6V
IOUT = 10mA
to be measure on LX pin
IOUT = 10mA
IOUT = 50mA
IOUT = 100mA
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
MIN
2.7
0.4
0.25
MIN
2.9
0.4
0.25
MIN
3.2
0.4
0.25
TYP
2.8
0.7
0.8
0.6
0.5
18
760
0.1
150
75
82
83
82
MAX
2.9
1.1
1.2
TYP
3
0.7
0.8
0.6
0.5
18
750
0.1
150
75
82
84
82
MAX
3.1
1.1
1.2
TYP
3.3
0.7
0.8
0.6
0.5
18
750
0.1
150
75
83
85
84
MAX
3.4
1.1
1.2
0.3
0.3
0.3
UNIT
V
V
V
V
V
µA
mΩ
µA
KHz
%
%
%
%
UNIT
V
V
V
V
V
µA
mΩ
µA
KHz
%
%
%
%
UNIT
V
V
V
V
V
µA
mΩ
µA
KHz
%
%
%
%
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UC3500

CMOS IC
ELECTRICAL CHARACTERISTICS(Cont.)
UC3500-3.6V (VIN =2.2V)
PARAMETER
Output Voltage
SYMBOL
VOUT
TEST CONDITIONS
IOUT = 10mA
IOUT = 0
IOUT = 1mA
IOUT = 0
IOUT = 1mA
IOUT = 0
ILX = 100mA
VLX = 4V, VOUT = 3.9V
IOUT = 10mA
to be measure on LX pin
IOUT = 10mA
IOUT = 50mA
IOUT = 100mA
MIN
3.49
TEST CONDITIONS
IOUT = 10mA
IOUT = 0
IOUT = 1mA
IOUT = 0
IOUT = 1mA
IOUT = 0
ILX = 100mA
VLX = 4V, VOUT = 4.3V
IOUT = 10mA
to be measure on LX pin
IOUT = 10mA
IOUT = 50mA
IOUT = 100mA
MIN
3.88
TEST CONDITIONS
IOUT = 10mA
IOUT = 0
Start-up Voltage (VIN-VF) (Note)
VSTART
IOUT = 1mA
IOUT = 0
Hold-on Voltage
VHOLD
IOUT = 1mA
Supply Current
ISUPPLY
IOUT = 0
Internal Switch RDS(ON)
RLX
ILX = 100mA
Internal Leakage Current
ILX(LEAK)
VLX = 4V, VOUT = 5.3V
Maximum Oscillator Frequency
fOSC
IOUT = 10mA
Oscillator Duty Cycle
Dty
to be measure on LX pin
IOUT = 10mA
Efficiency
η
IOUT = 50mA
IOUT = 100mA
Note: VF references to the forward voltage of the diode.
MIN
4.85
Start-up Voltage (VIN-VF) (Note)
VSTART
Hold-on Voltage
VHOLD
Supply Current
Internal Switch RDS(ON)
Internal Leakage Current
Maximum Oscillator Frequency
Oscillator Duty Cycle
Efficiency
ISUPPLY
RLX
ILX(LEAK)
fOSC
Dty
η
UC3500-4.0V (VIN =2.4V)
PARAMETER
Output Voltage
SYMBOL
VOUT
Start-up Voltage (VIN-VF) (Note)
VSTART
Hold-on Voltage
VHOLD
Supply Current
Internal Switch RDS(ON)
Internal Leakage Current
Maximum Oscillator Frequency
Oscillator Duty Cycle
Efficiency
ISUPPLY
RLX
ILX(LEAK)
fOSC
Dty
η
UC3500-5.0V (VIN = 3.0V)
PARAMETER
Output Voltage
SYMBOL
VOUT
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www.unisonic.com.tw
0.4
0.25
0.4
0.25
0.4
0.25
TYP
3.6
0.7
0.8
0.6
0.5
18
750
0.1
150
75
84
86
85
MAX
3.71
1.1
1.2
TYP
4.0
0.7
0.8
0.6
0.5
19
740
0.1
150
75
85
87
85
MAX
4.12
1.1
1.2
TYP
5.0
0.7
0.8
0.6
0.5
19
730
0.1
150
75
86
88
85
MAX
5.15
1.1
1.2
0.3
0.3
0.3
UNIT
V
V
V
V
V
µA
mΩ
µA
KHz
%
%
%
%
UNIT
V
V
V
V
V
µA
mΩ
µA
KHz
%
%
%
%
UNIT
V
V
V
V
V
µA
mΩ
µA
KHz
%
%
%
%
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UC3500

CMOS IC
PRINCIPLE OF OPERATION
The UTC UC3500 consists of a Band-Gap reference voltage source, error amplifier, VFM control logic core,
oscillator, VLX limiter amplifier, N-channel MOSFET switching transistor and output voltage divider network.
The device compares the Band-Gap reference voltage with the feedback voltage from the output through divider
network. In TON phase, the energy is transferred from the battery to the inductor. The switch is turned off after a
maximum on time set to 2.5µs. In TOFF phase, the energy stored in the inductor is transferred to the load. This
process is continuously performed to ensure stable output voltage. Until the output voltage reaches the expected
value.
Therefore, in case of light load, the device works in PFM mode. In heavy load condition, the device works in
continuous mode, the frequency range up to a maximum 150 KHz set by the built in oscillator. In over current
conditions, the Ton time is shorted; the switching frequency will be higher than 150 KHz.

TYPICAL APPLICATION CIRCUIT

RECONMMENDED COMPONENTS
L
D
CIN
COUT
:47μH (Sunida CD54 Fosc=500kHz)
:MA737, or MBRM110L
:10V 4.7μF (Tantalum)
:16V 47μF (Tantalum)
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UC3500

CMOS IC
TYPICAL CHARACTERISTICS
UC3500-2.5V
Output Waveform of LX
Output Waveform of LX
4
4
3
3
2
2
1
1
0
0
3
2
1
0
2
1
0
50
50
0
0
-50
3
-50
0
25
50
75
100 125 150 175 200 225 250
Time(µs)
IOUT=1mA
0
25
50
75
100 125 150 175 200 225 250
Time(ms)
IOUT=10mA
Output Waveform of LX Under
Maximum Frenquency
4
3
2
1
0
-1
0
5
10
15
Time(µs)
25
20
focs=166kHz,
Dty:83%
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UC3500

CMOS IC
TYPICAL CHARACTERISTICS(Cont.)
UC3500-2.7V
Output Waveform of LX
Output Waveform of LX
4
4
3
3
2
2
1
1
0
0
3
2
1
0
2
1
0
50
50
0
0
-50
3
-50
0
25
50
75
100 125 150 175 200 225 250
Time(µs)
IOUT=1mA
0
25
50
75
100 125 150 175 200 225 250
Time(ms)
IOUT=10mA
Output Waveform of LX Under
Maximum Frenquency
4
3
2
1
0
-1
0
5
10
15
Time(µs)
25
20
focs=166kHz,
Dty:83%
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
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QW-R502-072.I
UC3500

CMOS IC
TYPICAL CHARACTERISTICS(Cont.)
UC3500-3.3V
Output Waveform of LX
Output Waveform of LX
4
4
3
3
2
2
1
1
0
0
3
2
1
0
2
1
0
50
50
0
0
-50
3
-50
0
25
50
75
100 125 150 175 200 225 250
IOUT=1mA
0
25
50
75
100 125 150 175 200 225 250
Time(ms)
IOUT=10mA
Output Waveform of LX(V)
Time(µs)
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UC3500
CMOS IC
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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