Datasheet

UNISONIC TECHNOLOGIES CO., LTD
UC1100
Preliminary
CMOS IC
LOW-POWER HIGH PRECISION
CC/CV PRIMARY SIDE
SWITCHING REGULATOR

6
DESCRIPTION
The UTC UC1100 is a primary control unit for switch mode
charger and adapter applications. The controlled variable is
transferred by an auxiliary winding from the secondary to the
primary side. The device uses Pulse Frequency Modulation (PFM)
method to build discontinuous conduction mode (DCM) flyback
power supplies.
The UTC UC1100 operates in primary-side sensing and
regulation. Opto-coupler and TL431 could be eliminated. It also
eliminates the need of loop compensation circuitry while
maintaining stability. The UTC UC1100 achieves excellent
regulation and high average efficiency, yet meets the requirement
for no-load consumption less than 30mW.
The UTC UC1100 achieves high precision CV/CC regulation
and high power efficiency. It offers comprehensive protection
coverage with auto-recovery features including Cycle-by-cycle
current limiting, output over voltage protection, feedback loop open
protection, short circuit protection, leading edge blanking, VCC
under voltage lockout, etc.

4
1
2
3
SOT-26
FEATURES
* Primary side control for rectangular constant current and
constant voltage output
* 30mW no-load input power feasible
* Tight CC regulation performance
* Sub-microampere start-up current
* Eliminates control loop compensation circuitry
* Eliminates opto-coupler and secondary CV/CC control
circuitry

5
* Random frequency modulation to reduce system EMI
* Flyback topology in DCM operation
* Open feedback protection
* Built-in soft start
* Short circuit protection
ORDERING INFORMATION
Ordering Number
UC1100G-AG6-R
www.unisonic.com.tw
Copyright © 2015 Unisonic Technologies Co., Ltd
Package
SOT-26
Packing
Tape Reel
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UC1100

Preliminary
MARKING INFORMATION

PIN CONFIGURATION

PIN DESCRIPTION
PIN NO.
1
2, 5
3
4
6

CMOS IC
PIN NAME
OUT
GND
VCC
CS
FB
DESCRIPTION
This pin drives the base of external power NPN switch
Ground
Supply voltage
The primary current sense
The voltage feedback from the auxiliary winding
BLOCK DIAGRAM
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www.unisonic.com.tw
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QW-R129-007.a
UC1100

Preliminary
CMOS IC
ABSOLUTE MAXIMUM RATING
PARAMETER
SYMBOL
RATINGS
UNIT
Supply Voltage
VCC
-0.3~36
V
Voltage at CS, OUT to GND
-0.3~7
V
FB Input
-40~10
V
Output Current at OUT
Internally limited
A
ESD (Machine Model)
200
V
1000
ESD (Human Body Model)
V
Operating Junction Temperature
TOPR
150
°C
Storage Temperature
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.

THERMAL RESISTANCES CHARACTERISTICS
PARAMETER
Junction to Ambient

SYMBOL
θJA
RATINGS
250
UNIT
°C/W
ELECTRICAL CHARACTERISTICS (VCC=15V, TA=25°C, unless otherwise specified.)
PARAMETER
UVLO SECTION
Start-Up Threshold
Minimal Operating Voltage
STANDBY CURRENT SECTION
Start-Up Current
Operating Current
DRIVE OUTPUT SECTION
Sink
OUT Maximum Current
Source
CURRENT SENSE SECTION
Current Sense Threshold
SYMBOL
MIN
TYP
MAX
UNIT
16
7.2
18.5
9
21
10.2
V
V
350
3
400
µA
µA
50
40
60
80
mA
mA
VCS
∆
V
Equivalent Current Sense Voltage
CS , eq
Note 1
VCS , eq
Accuracy
455
510
545
mV
3
%
Pre-Current Sense
Leading Edge Blanking
FEEDBACK INPUT SECTION
Feedback Pin Input Leakage Current
Feedback Threshold
365
410
500
455
mV
ns
2.0
3.59
2.5
3.83
3.1
4.07
µA
V
VTH (ST)
VOPR(min)
IST
VCC=VTH (ST)-0.5V, Before Start-Up
ICC(OPR) Static
IOUT
VCS(PRE)
Note: The output current is given by IOUT
IFB
VFB=4V
VFB
V , eq NP
= CS
×
RCS
NS
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
TEST CONDITIONS
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UC1100

Preliminary
CMOS IC
OPERATION DESCRIPTION
The UTC UC1100 is a primary control unit for switch mode charger and adapter applications. It operates in
primary-side sensing and regulation. Opto-coupler and TL431 could be eliminated. Proprietary built-in CV and CC
control can achieve high precision CV/CC performance. It uses Pulse Frequency Modulation (PFM) method to build
discontinuous conduction mode (DCM) flyback power supplies.
Startup control
The VCC pin of UTC UC1100 is connected to the line input through a resistor. A large value startup resistor can be
used to minimize the power loss in application because the start current of UTC UC1100 is very low. When the VCC
voltage reaches VTH (ST), the internal startup circuit is disabled and the IC turns on.
Operating Current
The Operating current of UTC UC1100 is as low as 320uA. Good efficiency and very low standby power can be
achieved.
Constant Voltage Operation
The output voltage is defined by the transmission ratio between the secondary and auxiliary winding. The UTC
UC1100 captures the auxiliary winding feedback voltage at FB pin and operates in constant-voltage (CV) mode to
regulate the output voltage. The auxiliary voltage reflects the output voltage is given by:
N
VAUX = A ×(VO + ∆V)
(1)
NS
Where △V indicates the drop voltage of the output diode.
Figure1. Auxiliary voltage waveform
Via a resistor divider connected between the auxiliary winding and FB, the VAUX is sampled at the Tsampling end
and it is hold until the next sampling. The sampled voltage is compared with 4V reference voltage and the error is
amplified. The error amplifier output reflects the load condition and controls the Toff time to regulate the output
voltage, thus constant output voltage can be achieved.
Constant Current Operation
When the sampled voltage is below 4V reference voltage and the error amplifier output reaches its maximum, thus
UTC UC1100 operates in constant-current (CC) mode. The CC point and maximum output power can be externally
adjusted by external current sense resistor Rcs. The larger Rcs, the smaller CC point is, and the smaller output
power becomes.
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QW-R129-007.a
UC1100

Preliminary
CMOS IC
OPERATION DESCRIPTION (Cost.)
Figure2. Adjustable output power by changing Rcs
Figure3. Secondary current waveform
In CC operation, the CC loop control function of UTC UC1100 will keep a fixed proportion between secondary
inductance de-magnetization time (Tdemag) and switching cycle time (Tsw). The fixed proportion is
Tdemag 4
=
Tsw
7
(2)
Thus the output current is given by:
Iout =
1 NP
Tdemag 2 NP
×
× Ipk ×
= ×
× Ipk
2 NS
Tsw
7 NS
(3)
Current Sensing and Leading Edge Blanking
Cycle-by-cycle current limiting is offered in UTC UC1100. The switch current is detected by a sense resistor into
the CS pin. When the power switch is turned on, a turn-on spike will occur on this resistor. A 750ns leading-edge
blanking is built in to avoid false-termination of the switching pulse so that the external RC filtering is no longer
needed.
Drive BJT
The driver is a push pull stage with the supply voltage VCC. It provides the driving current for the external power
bipolar transistor. The output signal is current-limited to IOUT(SOURCE).
Protection Control
Good power supply system reliability is achieved with its comprehensive protection features including output
over-voltage protection, feedback loop open protection, Cycle-by-cycle current limiting, short circuit protection,
leading edge blanking and UVLO, etc.
VCC is supplied by transformer auxiliary winding output. The output of UTC UC1100 is shutdown when VCC drops
below VOPR(MIN) and the power converter enters power on start-up sequence thereafter.
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
5 of 6
QW-R129-007.a
UC1100
Preliminary
CMOS IC
TYPICAL APPLICATION CIRCUIT

F1
L
2
L1
BD1
4
1
2
1
C1 +
N
R13
C4
R4
C2 +
1
T1
C5
A
21V/0.3A
D3
3
C6 +
R1
R14
R5
4
GND
B
R2
D1
R3
D2
5
R6
3
3
CY1
VCC
U1
C3 +
Q1
R12
4
6
2
CS
5
2
OUT 1
GND
GND
FB
C7
R11
R10
R8
BOM
Reference
F1
BD1
C1, C2
C3
C4
C5
C6
C7
L1
T1
D1
D2
D3
Q1
Component
0.5A/250V
B6S
EC 4.7μF/400V 105°C
EC 4.7μF/50V 105°C
CC 102P/1KV
NC
EC 220μF/35V 105°C
NC
1.2mH
EE-16
1N4007, SMA
BAV21, SOD-123
MGBR3200, DO-201AD
MJE13003, TO-126
Reference
U1
R1, R2
R3
R4
R5
R6
R8
R10
R11
R12
R13
R14
CY1
Component
UC1100, SOT-26
1MΩ 1206
1.5MΩ 1206
200kΩ 1206
22Ω 0805
3.9Ω 0805
940mΩ 1206
20kΩ 0805
4.3kΩ 0805
1kΩ 0805
NC
24kΩ 1206
Y1 102P/400V
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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