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SC4501 2Amp, 2MHz Step-Up Switching Regulator with Soft-Start
POWER MANAGEMENT Description
The SC4501 is a high-frequency current-mode step-up switching regulator with an integrated 2A power transistor. Its high switching frequency (programmable up to 2MHz) allows the use of tiny surface-mount external passive components. Programmable soft-start eliminates high inrush current during start-up. The internal switch is rated at 32V making the converter suitable for high voltage applications such as Boost, SEPIC and Flyback.
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Features
u u u u u u u u u Low saturation voltage switch: 220mV at 2A Constant switching frequency current-mode control Programmable switching frequency up to 2MHz Soft-Start function Input voltage range from 1.4V to 16V Output voltage up to 32V Low shutdown current Adjustable undervoltage lockout threshold Small low-profile thermally enhanced packages
The operating frequency of the SC4501 can be set with an external resistor. The ability to set the operating frequency gives the SC4501 design flexibilities. A dedicated COMP pin allows optimization of the loop response. The SC4501 is available in thermally enhanced 8-Pin MSOP and 10-pin MLPD packages.
Applications
u u u u u u u
Flat screen LCD bias supplies TFT bias supplies XDSL power supplies Medical equipment Digital video cameras Portables devices White LED power supplies
Typical Application Circuit
VIN 5V 6 OFF ON 3 C1 2.2 µF 8 IN SHDN SC4501 SS GND C3 47nF 4 COMP ROSC 7 R4 C4 1 R3 C6 R2 20K 5 SW FB 2 C2 10 µF L1 D1 VOUT 12V, 0.7A R1 174K
10BQ015
Efficiency
95 10.5µH, 700KHz 90 85 4.7µH, 1.4MHz
Efficiency (%)
80 3.3µH, 2MHz 75 70 65 60
All Capacitors are Ceramic. MSOP-8 Pinout
f / MHz 0.7 1.35 2 R3 / KΩ 22.1 30.9 63.4 R4 / KΩ 22.1 9.31 4.75 C4 / pF 2200 820 470 C6 / pF 22 L1 / µH 10.5 (Falco D08019) 4.7 (Falco D08017) 3.3 (Coilcraft DO1813P)
55 50 0.0 0.1 0.2 0.3 0.4
VIN = 5V VOUT = 12V 0.5 0.6 0.7
Load Current (A)
Figure 1(a). 5V to 12V Boost Converter.
Figure 1(b). Efficiencies of 5V to 12V Boost Converters at 700KHz, 1.4MHz and 2MHz.
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Revision: October 25, 2005
SC4501
POWER MANAGEMENT Absolute Maximum Rating
Exceeding the specifications below may result in permanent damage to the device, or device malfunction. Operation outside of the parameters specified in the Electrical Characteristics section is not implied.
Parameter Supply Voltage SW Voltage FB Voltages SHDN Voltage
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Symbol VIN VSW VFB VSHDN Range TA θJA θJA TJ TSTG TLEAD ESD
Typ -0.3 to 18 -0.3 to 32 -0.3 to 2.5 -0.3 to VIN + 1 -40 to +85 40
Units V V V V °C °C/W
Thermal Resistance Junction to Ambient (MSOP-8) Thermal Resistance Junction to Ambient (MLPD-10) Maximum Junction Temperature Storage Temperature Range Lead Temperature (Soldering)10 sec ESD Rating (Human Body Model)
40 160 -65 to +150 260 2000 °C °C °C V
Electrical Characteristics
Unless specified: VIN = 2V, SHDN = 1.5V, ROSC = 7.68kΩ, -40°C < T A = TJ < 85°C
Parameter Undervoltage Lockout Threshold Maximum Operating Voltage Feedback Voltage Feedback Voltage Line Regulation FB Pin Bias Current Error Amplifier Transconductance Error Amplifier Open-Loop Gain COMP Source Current COMP Sink Current VIN Quiescent Supply Current VIN Supply Current in Shutdown Switching Frequency Maximum Duty Cycle Minimum Duty Cycle Switch Current Limit Switch Saturation Voltage
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Test Conditions
Min
Typ 1.3
Max 1.4 16
Unit V V V V %
TA = 25°C -40°C < TA < 85°C 1.5V < VIN < 16V
1.224 1.217
1.242
1.260 1.267
0.01 40 60 49 80
nA µΩ−1 dB µA µA
VFB = 1.1V VFB = 1.4V VSHDN = 1.5V, VCOMP = 0 ( Not Switching ) VSHDN = 0 1.3 85
5 5 1.1 10 1.5 90 0 2 2.8 220 350 1.6 18 1.7
mA µA MHz % % A mV
ISW = 2A
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SC4501
POWER MANAGEMENT Electrical Characteristics (Cont.)
Unless specified: VIN = 2V, SHDN = 1.5V, ROSC = 7.68kΩ, -40°C < T A = TJ < 85°C
Parameter Switch Leakage Current Shutdown Threshold Voltage Shutdown Pin Current Soft-Start Charging Current
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Test Conditions VSW = 5V
Min
Typ 0.01
Max 1 1.18
Unit µA V µA
1.02 VSHDN = 1.2V VSHDN = 0 VSS = 0.3V
1.1 -4.6 0 1.5 160 10
0.1
µA µA °C °C
Thermal Shutdown Temperature Thermal Shutdown Hysteresis
Pin Configurations
TOP VIEW
Ordering Information
Device(1)(2) SC4501MLTRT SC4501MSETRT(3) SC4501EVB Package MLPD-10 -40 to 85°C MSOP-8-EDP Evaluation Board Temp. Range( TA)
(10 Pin - MLPD, 3 x 3mm)
Notes: (1) Only available in tape and reel packaging. A reel contains 3000 devices for MLP package and 2500 devices for MSOP. (2) Lead free product. This product is fully WEEE and RoHS compliant. (3) Contact factory for availability.
TOP VIEW COMP 1 FB 2 SHDN 3 GND 4 8 SS 7 ROSC 6 IN 5 SW
(8 Pin MSOP-EDP)
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SC4501
POWER MANAGEMENT Pin Descriptions Block Diagram (MSOP-8)
Pin 1 2 Pin Name COMP FB Pin Function The output of the internal transconductance error amplifier. This pin is used for loop co.