UNISONIC TECHNOLOGIES CO., LTD UC3550
PWM CONTROLLED， PWM/PFM SWITCHABLE STEP-UP DC-DC CONTROLLER
3 2 1
CMOS IC
DESCRIPTION
The UTC UC3550 series is a compact, high efficiency, step-up DC/DC controllers includes an error amplifier, oscillator, PWM comparator, skip cycle comparator, voltage reference, soft-start, and high speed lower ON-resistance driver for driving external power devices (NMOS or NPN) ,Additionally, a CE (chip enable) function that reduces power consumption during shut-down mode. That typically operated from a single-or dual-cell battery packs. It have a driver pin ,ext pin, for connecting to an external transistor （NMOS or NPN）. a lower ON-resistance external transistor can obtain larger output current. With only external components, this series allow a simple means to accommodate high output current applications. The UTC UC3550 series goes automatically into skip switching cycles under light load condition to maintain high efficiency.
5 4
SOT-25
*Pb-free plating product number: UC3550L
FEATURES
* Input voltage range：0.9~8V * Output voltage range：1.8~6V programmable in 0.1V with high accuracy ± 2.5% * High efficiency 88%（typ.） * Low start-up voltage of 0.9V typical at IOUT = 1.0mA * Oscillator frequency: 300kHz.（±20%） * Chip enable pin with pull-up current source * High output current up to 1000mA (VIN = 2.0V, VOUT =3.3V)
ORDERING INFORMATION
Order Number Normal Lead Free Plating UC3550-xx-AF5-R UC3550L-xx-AF5-R Package SOT-25 Packing Tape Reel
UC3550L-xx-AF5-R
(1)Packing Type (2)Package Type (3)Voltage Code (4)Lead Plating
(1) R: Tape Reel (2) AF5: SOT-25 (3) xx: reference to Marking Information (4) L: Lead Free Plating, Blank: Pb/Sn
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QW-R502-082,A
UC3550
MARKING INFORMATION
PACKAGE VOLTAGE CODE MARKING
CMOS IC
3
SOT-25 33:3.3V 50:5.0V
2 U5XX
1
Voltage Code 4 5
Lead Plating
PIN CONFIGURATION
NC 3 OUT 2 CE 1
4 GND
5 EXT
PIN DESCRIPTION
PIN NO 1 2 3 4 5 PIN NAME CE OUT NC GND EXT DESCRIPTION Chip Enable: The chip is enabled if a voltage equal to or greater than 1.0V or left floating is applied. The chip is disabled if a voltage less than 0.3V is applied. Output voltage monitor, IC internal power supply No connection Ground External transistor drive
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
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QW-R502-082,A
UC3550
BLOCK DIAGRAM
CMOS IC
OUT 2
NC 3
+ -
Error Amplifier
PWM COMP
Buffer driver
5 EXT
~5mV
+ Skip COMP
Ramp Oscillator
120nA
Voltage reference and soft start GND 4
CE 1
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
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QW-R502-082,A
UC3550
ABSOLUTE MAXIMUM RATING
CMOS IC
PARAMETER SYMBOL RATINGS Supply Voltage VOUT -0.3~8 -0.3 ~ 8 VEXT EXT Voltage EXT Sink/Source Current IEXT -150 ~ +150 CE Input Voltage Range VCE -0.3 ~ 12.0 CE Input Current Range ICE -155 ~ 155 Power Dissipation (Ta=25℃) PD 500 Junction Temperature TJ +150 Operating Temperature TOPR -40 ~ +85 Storage Temperature TSTG -55 ~ +150 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.
UNIT V V mA V mA mW ℃ ℃ ℃
THERMAL DATA
PARAMETER Thermal Resistance Junction to Air SYMBOL θJA RATINGS 250 UNIT ℃/W
ELECTRICAL CHARACTERISTICS (Ta=25℃, fOSC＝300kHz, unless otherwise specified)
UC3550-3.3V PARAMETER OSCILLATOR Frequency Frequency Temperature Coefficient Maximum PWM Duty Cycle Minimum Start-up Voltage Minimum Start-up Voltage Minimum Start-up Voltage Temperature Coefficient Minimum Operation Hold Voltage Soft-Start Time CE (PIN 1) CE Input Voltage： High State, Device Enabled Low State, Device Disabled
CE Input Current： High State, Device Enabled Low State, Device Disabled SYMBOL fOSC △f DMAX VSTART1 VSTART2 TEST CONDITIONS VOUT=VSET×0.96 Ta=-40℃ ~ 85℃ VOUT=VSET×0.96 IOUT=0mA IOUT=1mA MIN 240 70 TYP 300 0.10 80 800 900 -1.6 600 60 700 250 MAX 360 90 900 1000 UNIT kHz %/℃ % mV mV mV/℃ mV ms
△VSTART Ta=-40℃ ~ 85℃
VOPR tSS IOUT=0mA VOUT=VSET
VCEH VCEL ICEH ICEL REXTH REXTL VOUT
VOUT=VSET×0.96
900 680
mV mV µA µA Ω Ω V ppm/℃
VOUT=VCE=5.0V VOUT=5.0V, VCE=0V VEXT=VOUT-0.4V VEXT=0.4V
-0.5 0
0 0.15 11 8
0.5 0.5 15 12 3.383
EXT (PIN 5)
ON Resistance EXT “H” EXT “L”
TOTAL DEVICE Output Voltage Output Voltage temperature coefficient Operating Current Stand-by Current
Off-State Current Efficiency
3.218 Ta=-40 ~ 85℃ VOUT=VCE=VSET×0.96 VOUT=VCE=VSET+0.5V VOUT=5.0V, VCE=0V, Ta=-40 ~ +85℃ IOUT = 200mA, VIN = 2.0V
3.3 150 103 15 0.6
△VOUT
IDD ISTN-BY IOFF η
160 38 1.5
µA µA µA %
80
88
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www.unisonic.com.tw
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QW-R502-082,A
UC3550
ELECTRICAL CHARACTERISTICS (Cont.)
UC3550-5.0V PARAMETER OSCILLATOR Frequency Frequency Temperature Coefficient Maximum PWM Duty Cycle Minimum Start-up Voltage Minimum Start-up Voltage Minimum Start-up Voltage Temperature Coefficient Minimum Operation Hold Voltage Soft-Start Time CE (PIN 1) CE Input Voltage ： High State, Device Enabled Low State, Device Disabled
CE Input Current ： High State, Device Enabled Low State, Device Disabled SYMBOL fOSC △f DMAX VSTART1 VSTART2 TEST CONDITIONS VOUT=VSET×0.96 Ta=-40℃ ~ 85℃ VOUT=VSET×0.96 IOUT=0mA IOUT=1mA MIN 240 70 TYP 300 0.1 80 800 900 -1.6 600 60
CMOS IC
MAX 360 90 900 1
UNIT kHz %/℃ % mV V mV/℃
△VSTART Ta=-40℃ ~ 85℃
VOPR tSS IOUT=0mA VOUT=VSET
700 200
mV ms
VCEH VCEL ICEH ICEL REXTH REXTL VOUT
VOUT=VSET×0.96
900 680
mV mV µA µA Ω Ω V ppm/℃ 220 38 1.5 µA µA µA %
VOUT=VCE=5.0V VOUT=5.0V, VCE=0V VEXT=VOUT-0.4V VEXT=0.4V
-0.5 0
0 0.15 6 6
0.5 0.5 10 10 5.125
EXT (PIN 5)
ON Resistance EXT “H” EXT “L”
TOTAL DEVICE Output Voltage Output Voltage temperature coefficient Operating Current Stand-by Current
Off-State Current Efficiency
4.875 Ta=-40 ~ 85℃ VOUT=VCE=VSET×0.96 VOUT=VCE=VSET+0.5V VOUT=5.0V, VCE=0V, Ta=-40 ~ +85℃ IOUT = 200mA, VIN = 2.0V
5 150 136 15 0.6
△VOUT
IDD ISTN-BY IOFF η
80
88
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
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QW-R502-082,A
UC3550
TYPICAL STEP-UP CONVERTER APPLICATION
CMOS IC
10uH V IN V OUT 220uF
CE EXT
1
OUT
5
UTC UC3550
GND
2 10uF
NC
0.1µ 3
4
Step -up Converter using external MOSFET
10uH VIN Cb 3000P
CE EXT
VOUT 220 uF
1
OUT
5
UTC UC3550
Rb 560
GND
2 10uF
NC
0.1 µ 3
4
Step -up Converter using external NPN
Recommended components NmosTr ：XP161A0390PR/ (Torex) or NTGS3446T1（ON SEMI） ：10Uh(sunida CD54 fosc＝300kHz) L ：MA737, or MBRM110L SD ：10V 10uF (tantalum) Cin ：16V220uF (tantalum) CL
NPN Tr type Tr ：2SD1628(Sanyo)，MMJT9410 Rb ：500～1000Ω(Adjust according to load and Tr. hFE levels) Cb ：3000p（ceramic type）
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
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QW-R502-082,A
UC3550
EXTERNAL COMPONENT SELECTION
CMOS IC
Inductor Selection An inductor value of 10uH performs well in most application. The UC3550 series also work with inductors in the 4.7uH to 12uH range. An inductor with higher peak inductor current tends a higher output voltage ripple（IPEAK x output filter capacitor ESR）. The inductor’s DC resistance significantly affects efficiency. Output Capacitor Selection The output ripple voltage（IPEAK x output filter capacitor ESR）is the product of the peak inductor current and the output capacitor Equivalent Series Resistance (ESR). Best performances are obtained with good high frequency characteristics capacitors and low ESR. The best compromise for the value of the Output Capacitance is 220F Tantalum Capacitor. The output capacitor as close as possible to the device pins. Input Capacitor Selection The Input Capacitor is required to compensate, if present, the series impedance between the Supply Voltage Source and the Input Voltage of the Application. A value of 10 F is enough to guarantee stability for distances less than 2". In any case we suggest to connect both capacitors, The input capacitor as close as possible to the device pins. Diode Selection The Schottky diode with an high switching speed and a very low Forward Voltage (VF) is needed. Higher VF may cause lost power as heat in the diode, with a decrease of the Efficiency. Moreover, since the Output Voltage pin is also used as the device Supply Voltage, the Start-up Voltage (see related plots) is strictly due to the diode Forward Voltage at the rated Forward Current. External Component Selection An enhancement N-channel MOSFET or a bipolar NPN transistor can be used as the external switch transistor. since enhancement N-channel MOSFET is a voltage driven device, it is a more efficient switch than a BJT transistor. However, he MOSFET requires a higher voltage to turn on as compared with BJT transistor For enhancement N-channel MOSFET ( it is especially importance for RDS(ON),typically
