Datasheet

UNISONIC TECHNOLOGIES CO., LTD
UU28141
CMOS IC
1.4A BOOST FOR WHITE LED
DRIVER

DESCRIPTION
The UTC UU28141 is a high frequency, asynchronous boost
converter. The internal MOSFET can support up to 8 White LEDs
for backlighting and OLED power application, and the internal soft
start function can reduce the inrush current.
The UTC UU28141 uses current mode, 1.0MHz fixed frequency
architecture to regulate the LED current, which is set through an
external current sense resistor. Its low 300mV feedback voltage
reduces power loss and improves efficiency. The OVP pin monitors
the output voltage and turns off the converter if an over-voltage
condition is present due to an open circuit condition. The UTC
UU28141 includes under-voltage lockout, current limiting and
thermal shutdown protection preventing damage in the event of an
output overload.

FEATURES
* 2.5V~5.5V operating input voltage range
* Drives up to 8 series White LEDs
* 1.0MHz Fixed Switching Frequency
* Wide range for PWM dimming (200Hz~200KHz)
* Internal 1.4A switching current limit
* Over Voltage Protection (OVP)
* Internal Soft-start Function
* Current limit and Thermal shutdown protection
* Under voltage Lockout

ORDERING INFORMATION
Ordering Number
UU28141G-AE6-R

Package
SOT-23-6
Packing
Tape Reel
MARKING
www.unisonic.com.tw
Copyright © 2016 Unisonic Technologies Co., Ltd
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QW-R125-040.B
UU28141


PIN CONFIGURATION
SW
1
6
VCC
GND
2
5
OVP
FB
3
4
EN
PIN DESCRIPTION
PIN NO.
1
2
3
4
5
6

CMOS IC
PIN NAME
SW
GND
FB
EN
OVP
VCC
DESCRIPTION
Switching Pin.
Ground Pin.
Feedback Pin.
Chip Enable & Dimming pin. Active high. Internal pull low.
Over voltage detect pin.
Power Input Pin.
BLOCK DIAGRAM
VCC
UVLO and
POR
SW
REFERENCE
SOFTSTART
and BIAS
Thermal
Shutdown
ILIMIT
Current
Sense
+
+
EA
-
LPF
FB
- COMP
PWM
CONTROL
LOGIC
OVP
OVP
+
Shutdown
DRIVER
Enable
Logic
10ms
EN
OSCILLATOR
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GND
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QW-R125-040.B
UU28141

CMOS IC
ABSOLUTE MAXIMUM RATING (TA=25°C, unless otherwise specified)
PARAMETER
SYMBOL
RATINGS
UNIT
VCC Pin Voltage
VIN
-0.3 ~ 6
V
SW Pin Voltage
VSW
-0.3 ~ 33
V
OVP Pin Voltage
VOVP
-0.3 ~ 33
V
EN, FB Pins Voltage
-0.3 ~ VIN+0.3
V
Operating Junction Temperature
TOPR
-40 ~ +125
°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.

RECOMMENDED OPERATING CONDITIONS
PARAMETER
Input Supply Voltage
Ambient Temperature

SYMBOL
VIN
TA
RATINGS
2.5 ~ 5.5
-40 ~ +125
UNIT
V
°C
THERMAL CHARACTERISTICS
PARAMETER
SYMBOL
RATINGS
UNIT
Junction To Ambient
θJA
250
°C/W
Junction to Case
θJC
180
°C/W
Note: θJA is measured with the PCB copper are (need connect to GND of the UTC UU28141) of approximately 1 in2
(Multi-layer).

ELECTRICAL CHARACTERISTICS (VIN=5V, VEN=5V, IOUT=20mA, TA=25°C)
PARAMETER
Input Voltage Range
Input UVLO
UVLO Hysteresis
OVP Sense Voltage
Quiescent Current
Supply Current
Shutdown Current
FB Pin Voltage
FB Pin Current
Load Regulation
Line Regulation
EN Pin Voltage High
EN Pin Voltage Low
EN Hysteresis
EN Pin Sink Current
Switching Frequency
N-Channel MOSFET Current Limit (Note)
Switching Maximum Duty
Dimming Clock Rate
N-Switch RDS (ON)
Thermal Shutdown
Thermal Shutdown Protection Hysteresis
Note: Guaranteed by design.
SYMBOL
TEST CONDITIONS
VIN
UVLO Rising
VOV
ICCQ
IIN
ISD
VFB
IFB
27.5
VFB=0.5V, IOUT=0mA
VFB=0V, Switching
VEN=0V, TEN>20mS
0.285
1mA<IOUT<20mA
3V<VIN<4.3V
VENH
VENL
IIH
FOSC
CL
CL
DMAX
TYP
MAX
5.5
2.45
2.25
0.1
29
200
400
1
2
1
4
0.300 0.315
±100
1
1
1.4
0.4
0.75
Duty on 50%
0.1
1
1
1.4
1.9
92
0.2
RDS(ON)-N VIN=3.6V
TSD
TSH
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
MIN
2.5
0.5
155
25
1.25
200
1.0
UNIT
V
V
V
V
μA
mA
μA
V
nA
%
%
V
V
V
μA
MHz
A
A
%
KHz
Ω
°C
°C
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UU28141

CMOS IC
FUNCTION DESCRIPTION
Setting the ILED Current
Application circuit item shows the basic application circuit with UTC UU28141 adjustable output version. The
external resistor sets the LED output current according to the following equation:
ILED
20mA
350mA
REST
15Ω
0.857Ω
6mW
105mW
Under Voltage Lockout (UVLO)
To avoid mis-operation of the device at low input voltages an under voltage lockout is included that disables the
device, if the input voltage falls below (2.25V~100mV).
Over Voltage Protection
OVP measure the output voltage for open circuit protection. Connect OVP pin to the output at the top of the LED
string. If VOUT above 36V, the OVP protection is happened that stops the internal driver until VOUT below 36V.
Input Capacitor Selection
The input capacitor reduces the surge current drawn from the input and switching noise from the device. The input
capacitor impedance at the switching frequency shall be less than input source impedance to prevent high frequency
switching current passing to the input. A low ESR input capacitor sized for maximum RMS current must be used.
Ceramic capacitors with X5R or X7R dielectrics are highly recommended because of their low ESR and small
temperature coefficients. A 2.2uf ceramic capacitor for most applications is sufficient. For a lower output power
requirement application, this value can be decreased.
Output Capacitor Selection
The output capacitor is required to keep the output voltage ripple small and to ensure regulation loop stability. The
output capacitor must have low impedance at the switching frequency. Ceramic capacitors with X5R or X7R
dielectrics are recommended due to their low ESR and high ripple current. A 1uF ceramic capacitors works for most
of the applications. Higher capacitor values can be used to improve the load transient response.
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QW-R125-040.B
UU28141

CMOS IC
TYPICAL APPLICATION CIRCUIT
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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QW-R125-040.B
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