Datasheet

UNISONIC TECHNOLOGIES CO., LTD
UC3666
Preliminary
CMOS IC
DUAL CHANNEL 1A HIGH
EFFICIENCY STEP-DOWN
DC/DC CONVERTER

1
DESCRIPTION
DFN-10(3x3)
The UTC UC3666 is a dual channel high efficiency step-down
DC/DC converter with constant frequency and current mode. A
main switch and a synchronous rectifier for high efficiency are
contained in each converter, and thus an external Schottky diode is
saved. The output voltage can be adjusted to as low as 0.6V. With
input voltage range from 2.5V ~ 5.5V , each converter can deliver
1A current to the load. Due to the internally fixed 1.6MHz switching
frequency, small surface mount inductors and capacitors can be
used.
The UTC UC3666 is generally used in digital still cameras,
portable instruments, slim-type DVD, microprocessors and DSP
core supplies, wireless and DSL card, PDAs, smart phones,
cellular telephones and so on.

FEATURES
* high efficiency
* Current mode operation
* Input voltage varying from 2.5V to 5.5V
* Output current on each channel: 1A
* Fixed frequency operation
* 0.6V reference allows low output voltages
* Over-temperature protection circuit
* RoHS Compliant (100% green available)

ORDERING INFORMATION
Ordering Number
UC3666G-K10-3030-R
www.unisonic.com.tw
Copyright © 2015 Unisonic Technologies Co., Ltd
Package
DFN-10(3×3)
Packing
Tape Reel
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UC3666
Preliminary

MARKING

PIN CONFIGURATION
CMOS IC
Top View
EN1
1
10 SW1
FB1
2
9
GND1
VIN2
3
8
VIN1
GND2
4
7
FB2
SW2
5
6
EN2
Exposed Pad
On Backside

PIN DESCRIPTION
PIN NO.
PIN NAME
1
EN1
2
3
4
5
FB1
VIN2
GND2
SW2
6
EN2
7
8
9
10
FB2
VIN1
GND1
SW1
DESCRIPTION
Channel 1 Regulator Enable Control Input Pin. Drive EN1 above 1.5V to turn on
channel1.
Drive EN1 below 0.3V to turn it off (shutdown current < 0.1uA).
Channel 1 Voltage Feedback Pin
Channel 2 Supply Pin
Channel 2 Ground Pin
Channel 2 Power Switch Output
Channel 2 Regulator Enable Control Input Pin. Drive EN2 above 1.5V to turn on
channel2.
Drive EN2 below 0.3V to turn it off (shutdown current < 0.1uA).
Channel 2 Voltage Feedback Pin
Channel 1 Supply Pin
Channel 1 Ground Pin
Channel 1 Power Switch Output
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
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UC3666

Preliminary
CMOS IC
BLOCK DIAGRAM
VIN1
VIN2
EN1
EN2
EN
Logic
UVLO
Reference
+
+
Current
Sense
Amplifier
Slop Comp
Soft Start
-
M1
UG
FB1
FB2
0.6V
+
-
+
Error
Amplifier
PWM
Comparator
PWM
Logic
SW1
SW2
RS &
Drive
M2
Oscillator
LG
Clock
DCC
+
GND1
GND2
Zero-Current
Comparator
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
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UC3666

Preliminary
CMOS IC
ABSOLUTE MAXIMUM RATING
PARAMETER
SYMBOL
RATINGS
UNIT
Input Supply Voltage
VIN
GND-0.3 ~ +6.5
V
SW Voltage
-0.3 ~ VIN +0.3
V
ENB, VFB Voltage
-0.3 ~ VIN
V
SW Peak Current
1.5
A
Junction Temperature
TJ
125
°C
Operating Temperature
TOPR
-20 ~ +85
°C
Storage Temperature Range
TSTG
-65 ~ +150
°C
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.
The IC has a protection circuit against static electricity. Do not apply high static electricity or high voltage that
exceeds the performance of the protection circuit to the IC.

THERMAL DATA
PARAMETER
SYMBOL
Junction ambient
θJA
Note: The PCB area is 4 times larger than that of IC’s

RATINGS
72
UNIT
°C/W
ELECTRICAL CHARACTERISTICS
(Recommended Operating Conditions, unless otherwise specified; VIN=3.6V, TA=0 ~ 70°C (typical=25°C))
PARAMETER
SYMBOL
TEST CONDITIONS
MIN TYP MAX UNIT
Supply Voltage
VIN
2.5
5.5
V
Feedback Current
IVFB
-30
0.5
30
nA
TA=25°C
0.588 0.6 0.612
V
Regulated Feedback Voltage
VFB
-40°C≤TA≤85°C
0.582 0.6 0.618
V
Reference Voltage Line Regulation
∆VFB
VIN=2.5V ~ 5.5V
0.04
0.4
%V
Output Voltage Line Regulation
∆VOUT VIN=2.5V ~ 5.5V
0.04
0.4
%V
Output Voltage Load Regulation
VLOADRGE
0.5
%
Shutdown Current
IS
VEN=0V, VIN=5.5V
0.01
1
µA
SW Leakage Current
ILEAK
VEN=0V, VIN=5.5V, VSW=0V or 5.5V
-1
1
µA
PMOSFET On Resistance
RDSONP ISW=100mA
0.35
Ω
NMOSFET On Resistance
RDSONN ISW=100mA
0.24
Ω
Duty Cycle=100%
0.9
1.2
1.4
A
PMOSFET Current Limit
IPCL
Current Pulse Width<1ms
Oscillator Frequency
fOSC
1.2
1.6
2.0
MHZ
Thermal Shutdown Threshold
TS
145
°C
EN High Level Input Voltage
VEN
-40°C≤TA≤+85°C
0.9
V
EN Low Level Input Voltage
VEN
-40°C≤TA≤+85°C
0.3
V
EN Input Current
IEN
VEN=0V ~ VIN
-1
1
µA
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
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UC3666

Preliminary
CMOS IC
TYPICAL APPLICATION CIRCUIT
Adjustable Output Voltage
A resistive divider adjusts the output voltage of the UTC UC3656, which divides a 0.6V reference voltage at FB
pin. The output voltage can be obtained by the equation as follows:
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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