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AX5201
Step-up PWM DC/DC Converter
GENERAL DESCRIPTION The AX5201 is high efficient step-up DC/DC converter. Large output current is possible having a built in internal N channel MOSFET, and using an external coil and diode. The AX5201 can be operated at switching frequencies of 500 kHz allowing for easy filtering and low noise, the size of the external components can be reduced. Output voltage is programmable with 1.0V of standard voltage supply internal, and using externally connected components, output voltage (FB) can be set up at will. The soft-start time can be programmed by outside capacitor; the function prevents overshoot at startup. Build inside Current limit, Thermal Shutdown and enable functions. FEATURES - Input voltage:3V to 20V - Output voltage:3.3V to 32V - Duty ratio:0% to 85% PWM control - Oscillation frequency:500KHz. Enable and Thermal Shutdown function. Internal Current limit. Built-in N-channel MOSFET SOP-8L with Exposed pad Pb-Free package.
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BLOCK DIAGRAM
Vcc Phase Compensation + + Vref=1.0V Buffer Driver
FB
Regulator
SW
PWM Controller EN VEN 8uA
Thermal Shutdown
Oscillator
0.06V SGND PGND
SS
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Axelite Confidential Materials, do not copy or distribute without written consent. Rev.1.4 Jan.25, 2011
AX5201
PIN ASSIGNMET The package of AX5201 is SOP-8L-EP; the pin assignment is given by: Name
( Top View ) EN VCC FB SS 1 2 3 4 SOP-8L-EP (EP is connect to SW) Exposed pad 8 7 6 5 SGND PGND SW SW
Description
SGND Signal Ground pin. PGND Power Ground pin Power-off pin H:normal operation(Step-up) EN L:Step-up operation stopped VCC FB SW SS IC power supply pin Feedback pin Switch pin. Connect inductor and diode here. Soft-Start Pin. external
ORDER/MARKING INFORMATION
Order Information Top Marking
Logo
AX5201 XX X
Package Type ES: SOP-8L-EP Packing Blank : Tube A : Taping
5 2 01 AX Y Y WW X
Part number ID code:internal WW: 01~52 Year: 10=2010 11=2011
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ABSOLUTE MAXIMUM RATINGS (at TA=25°C) Characteristics Symbol VCC Pin Voltage Feedback Pin Voltage ON/OFF Pin Voltage Switch Pin Voltage SS Pin Voltage Power Dissipation Storage Temperature Range Operating Junction Temperature Thermal Resistance from Junction to case Thermal Resistance from Junction to ambient VCC VFB VEN VSW VSS PD TST TOPJ θJC θJA
Rating GND - 0.3 to GND + 22 GND - 0.3 to 6 GND - 0.3 to VCC GND - 0.3 to 34 GND - 0.3 to 6 Internally limited -40 to +150 -20 to +125 15 40
Unit V V V V V mW °C °C °C/W °C/W
Note : θJA is measured with the PCB copper area (connect to exposed pad) of approximately 1 in2(Multi-layer).
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Axelite Confidential Materials, do not copy or distribute without written consent. Rev.1.4 Jan.25, 2011
AX5201
ELECTRICAL CHARACTERISTICS (VCC = 5V, VOUT=12V, TA=25°C, unless otherwise specified) Characteristics Operating Supply Voltage Output Voltage Range Feedback Voltage Feedback Bias Current Quiescent Current Shutdown Supply Current Oscillation Frequency Line Regulation Load Regulation EN Pin Logic input threshold voltage EN Pin Input Current SS pin Current Switching Current Limit Internal MOSFET RDSON Efficiency Maximum Duty Cycle Minimum Duty Cycle Thermal shutdown Temp VSH VSL ISH ISL ISS ILIM-sw RDSON EFFI
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Symbol VCC VOUT VFB IFB ICCQ ISD FOSC
Conditions
Min Typ Max Units 3 3.3 20 32 V V V uA mA uA % % V uA uA uA A mΩ % % °C
IOUT=0.1A IOUT=0.1A VFB=1.5V force driver off VEN =0V SW pin VCC =3~0.8*VOUT IOUT=50m~1A High (regulator ON) Low (regulator OFF) VEN=2.5V (ON) VEN=0.3V (OFF)
0.98 1.00 1.02 2.0 0.1 0.5 4 6 1 10 1 1 20 -1 8 40 30 92 85 0 145 0.8 80 60 -
400 500 600 KHz
2.8 3.0 IOUT = 0.5A -
VCC=5V VCC=12V VCC=5V VOUT=12V
DCMAX VFB=0V DCMIN VFB=1.5V TSD
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Axelite Confidential Materials, do not copy or distribute without written consent. Rev.1.4 Jan.25, 2011
AX5201
APPLICATION CIRCUIT
VCC=5V L1 22uH U1 R1 100K 1 2 3 4 C1 470uF C7 0.1uF C3 Option C2 0.47uF EN Vcc FB SS AX5201 SGND PGND SW SW 8 7 6 5 C4 470uF C5 4.7uF R4 11K D1 B340A
Vout=12V
C8 0.47uF
R3 1K
VOUT = VFB (1 + FUNCTION DESCRIPTIONS PWM Control
R4 ), VFB = 1.0V, R3 = 1K ~ 3KΩ R3
The AX5201 consists of DC/DC converters that employ a pulse-width modulation (PWM) system. In converters of the AX5201, the pulse width varies in a range from 0 to 85%, according to the load current. The ripple voltage produced by the switching can easily be removed through a filter because the switching frequency remains constant. Therefore, these converters provide a low-ripple power over broad ranges of input voltage and load current.
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Setting the Output Voltage Application circuit item shows the basic application circuit with AX5201 adjustable output version. The external resistor sets the output voltage according to the following equation:
V
OUT
R4 1.0V 1 R3
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Axelite Confidential Materials, do not copy or distribute without written consent. Rev.1.4 Jan.25, 2011
AX5201
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