Datasheet

UNISONIC TECHNOLOGIES CO., LTD
UC3551
Preliminary
CMOS IC
ADVANCED PWM STEP-UP
DC-DC CONVERTER
„
DESCRIPTION
The UTC UC3551 is a step-up DC/DC converter with high
efficiency and low start-up voltage. It is operaded in stable
waveforms without external compensate. This device incorporates
an adaptive current mode PWM control loop in which an error
amplifier, ramp generator, comparator, switch pass element and
driver are included. Besides, this circuit provides a stable and high
efficient operation over a wide range of load currents.
The UTC UC3551 features high switching rate which is up to 450
KHz, making the external component counts less required.
Moreover, it features 17μA low quiescent current, which makes the
battery life longer. The low start-up input voltage below 1V makes
UTC UC3551 suitable for 1 to 4 battery cells applications of
providing up to 300mA output current.
Two external resistors determine the value of the output voltage.
The external power devices (NMOS or NPN) are derived by both
internal 2A switch and driver.
The UTC UC3551 is intended to be used in PDA, DSC, LCD
Panel, RF-Tags, MP3, portable instrument and wireless equipment.
„
FEATURES
* Low Start-up Input Voltage is as Low as 1.0V
* Efficiency up to 90%
* High Supply Capability to Deliver 3.3V 100mA with 1 Alkaline Cell
* Quiescent (Switch-off) Supply Current: 17µA
* Zero Shutdown Mode Supply Current
* Fixed Switching Frequency: 450KHz
* Both Internal and External Power Switches for Maximum Flexibility
„
ORDERING INFORMATION
Ordering Number
Lead Free
Halogen Free
UC3551L-AG6-R
UC3551G-AG6-R
UC3551L-AG6-R
Package
Packing
SOT-26
Tape Reel
(1)Packing Type
(1) R: Tape Reel
(2)Package Type
(2) AG6: SOT-26
(3)Lead Free
(3) G: Halogen Free, L: Lead Free
www.unisonic.com.tw
Copyright © 2011 Unisonic Technologies Co., Ltd
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UC3551
„
Preliminary
CMOS IC
MARKING INFORMATION
PACKAGE
VOLTAGE CODE
SOT-26
AD:ADJ
„
PIN CONFIGURATION
„
PIN DESCRIPTION
PIN NO.
1
2
3
4
5
6
PIN NAME
CE
EXT
GND
LX
VDD
FB
MARKING
DESCRIPTION
Chip enable UC3551 gets into shutdown mode when CE pin set to low.
Output pin for driving external NMOS
Ground
Pin for switching
Input positive power pin of UC3551
Feedback input pin Internal reference voltage for the error amplifier is 1.25V.
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
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UC3551
„
Preliminary
CMOS IC
BLOCK DIAGRAM
VLx Limiter
LX
Vref
VDD
Buffer
+
Control Circuit
GND
Chip Enable
EXT
-
FB
Over Temp
Detector
EN
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www.unisonic.com.tw
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UC3551
„
Preliminary
CMOS IC
ABSOLUTE MAXIMUM RATING
PARAMETER
SYMBOL
RATINGS
UNIT
Supply Voltage
VIN
− 0.3 ~ 7
V
LX Pin Switch Voltage
VLX
− 0.3 ~ (VDD + 0.8)
V
Other I/O Pin Voltages
− 0.3 ~ (VDD + 0.3)
V
LX Pin Switch Current
ILX
2.5
A
EXT Pin Driver Current
IEXT
200
mA
Operating Junction Temperature
TOPR
125
°C
Storage Temperature
TSTG
-65~+150
°C
Notes: 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.
„
THERMAL DATA
PARAMETER
SYMBOL
θJC
Junction to Case
„
RATINGS
145
UNIT
°C/W
ELECTRICAL CHARACTERISTICS
(TA = 25°C,VIN = 1.5V, VDD= 3.3V, Load Current = 0, unless otherwise specified)
PARAMETER
SYMBOL
CONDITIONS
Start-UP Voltage
VST
IL = 1mA
Operating VDD Range
VDD
VDD pin voltage
MIN
2
TYP
0.98
MAX
1.05
6.5
(Note )
UNIT
V
V
No Load Current I (VIN)
INO LOAD
VIN = 1.5V, VOUT = 3.3V
75
μA
Switch-off Current I (VDD)
ISWITCH OFF
VIN = 6V
17
μA
Shutdown Current I (VIN)
IOFF
CE Pin = 0V, VIN = 4.5V
0.01
1
μA
Feedback Reference Voltage
VREF
Close Loop, VDD = 3.3V
1.225 1.25
1.275
V
Switching Frequency
FS
VDD = 3.3V
450
KHz
Maximum Duty
DMAX
VDD = 3.3V
95
%
LX ON Resistance
VDD = 3.3V
0.3
Ω
Current Limit Setting
ILIMIT
VDD = 3.3V
2
A
EXT ON Resistance to VDD
VDD = 3.3V
5
Ω
EXT ON Resistance to GND
VDD = 3.3V
5
Ω
Line Regulation
∆VLINE
VIN = 1.5 ~ 2.5V, IL = 1mA
10
mV/V
Load Regulation
∆VLOAD
VIN = 2.5V, IL = 1 ~ 100mA
0.25
mV/mA
CE Pin Trip Level
VDD = 3.3V
0.4
0.8
1.2
V
Temperature Stability for Vout
Ts
50
ppm/°C
Thermal Shutdown
TSD
165
°C
Thermal Shutdown Hysterises
∆TSD
10
°C
Note: The CE pin shall be tied to VDD pin and inhibit to act the ON/OFF state whenever the VDD pin voltage may
reach to 5.5V or above.
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
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„
Preliminary
CMOS IC
TEST CIRCUIT
D1
L1
VIN
CIN
100µF
VOUT
C2
1µF
D1N5819
COUT
100µF
VDD
EN
LX
3.3~10µH
C1
102
UTC UC3551
FB
EXT
EXT
R2
1M
GND
„
R1
3M
TYPICAL APPLICATION CIRCUIT
D1
L1
VIN
CIN
100µF
VOUT
C2
1µF
D1N5819
COUT
100µF
VDD
EN
LX
3.3~10µH
C1
102
R1
3M
UTC UC3551
FB
EXT
EXT
R2
1M
GND
D1
L1
VIN
CIN
100µF
VOUT
C2
1µF
D1N5819
COUT
100µF
VDD
EN
LX
3.3~10µH
C1
102
R1
3M
UTC UC3551
M1
FB
EXT
NMOS
GND
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
R2
1M
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UC3551
Preliminary
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.
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
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