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PDF APW7303 Data sheet ( Hoja de datos )
| Número de pieza | APW7303 | |
| Descripción | 3A 24V 340kHz synchronous Buck Converter | |
| Fabricantes | ANPEC | |
| Logotipo |  |
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APW7303
3A 24V 340kHz synchronous Buck Converter
Features
General Description
• Wide Input Voltage from 4.5V to 24V
• 3A Continuous Output Current
• Adjustable Output Voltage from 0.92V to 20V
• Intergrated N-MOSFET
• Fixed 340kHz Switching Frequency
• Stable with Low ESR Ceramic Output Capacitors
• Power-On-Reset Detection
• Programmable Soft-Start
• Over-Temperature Protection
• Current-Limit Protection with Frequency Foldback
• Enable/Shutdown Function
• Small SOP-8P Packages
• Lead Free and Green Devices Available
(RoHS Compliant)
Applications
• LCD Monitor/TV
• Set-Top Box
• DSL, Switch HUB
• Notebook Computer
APW7303 is a 3A synchronous buck converter with inte-
grated power MOSFETs. The APW7303 design with a
current-mode control scheme, can convert wide input
voltage of 4.5V to 24V to the output voltage adjustable
from 0.92V to 20V to provide excellent output voltage
regulation.
The APW7303 is also equipped with Power-on-reset, soft-
start, and whole protections (over-temperature, and cur-
rent-limit) into a single package.
This device, available SOP-8P, provides a very compact
system solution external components and PCB area.
Pin Configuration
APW7303
BS 1
VIN 2
LX 3
GND 4
9
GND
8 SS
7 EN
6 COMP
5 FB
SOP-8P
(Top View)
9 Exposed Pad
The pin 4 must be connected to the pin 9 (Exposed Pad)
Simplified Application Circuit
VIN
APW7303
VOUT
ANPEC reserves the right to make changes to improve reliability or manufacturability without notice, and
advise customers to obtain the latest version of relevant information to verify before placing orders.
Copyright © ANPEC Electronics Corp.
Rev. A.4 - Nov., 2012
1
www.anpec.com.tw
Free Datasheet http://www.datasheetlist.com/
1 page  
APW7303
Typical Operating Characteristics
Refer to the “Typical Application Circuit”The test conditions are VIN=12V, VOUT=3.3V, L1=10µH, C2=22µF, TA= 25oC unless otherwise
specified.
Reference Voltage vs. Junction
Oscillator Frequency vs. Junction
Temperature
Temperature
Junction Temperature, TJ ( C)
VIN Input Current vs. Supply Voltage
VIN Supply Voltage , VIN(V)
Junction Temperature, TJ ( C)
Output Current vs. Efficiency
VOUT=5V
VOUT=3.3V
VOUT=2.5V
Output Current, IOUT(A)
Copyright © ANPEC Electronics Corp.
Rev. A.4 - Nov., 2012
5
www.anpec.com.tw
Free Datasheet http://www.datasheetlist.com/
5 Page 
APW7303
Function Description
Main Control Loop
The APW7303 is a constant frequency current mode
switching regulator. During normal operation, the inter-
nal N-channel power MOSFET is turned on each cycle
when the oscillator sets an internal RS latch and would
be turned off when an internal current comparator (ICMP)
resets the latch. The peak inductor current at which ICMP
resets the RS latch is controlled by the voltage on the
COMP pin, which is the output of the error amplifier
(EAMP). An external resistive divider connected between
VOUT and ground allows the EAMP to receive an output
feedback voltage VFB at FB pin. When the load current
increases, it causes a slight decrease in VFB relative to
the 0.92V reference, which in turn causes the COMP volt-
age to increase until the average inductor current matches
the new load current.
VIN Power-On-Reset (POR) and EN Under-voltage
Lockout
The APW7303 keep monitoring the voltage on VIN pin to
prevent wrong logic operations which may occur when
VIN voltage is not high enough for the internal control
circuitry to operate. The VIN POR has a rising threshold
of 4.1V (typical) with 0.5V of hysteresis.
An external under-voltage lockout (UVLO) is sensed at
the EN pin. The EN UVLO has a rising threshold of 2.5V
with 0.2V of hysteresis. The EN pin should be connected
a resistor divider from VIN to EN.
After the VIN and EN voltages exceed their respective
voltage thresholds, the IC starts a start-up process and
then ramps up the output voltage to the setting of output
voltage.
Over-Temperature Protection (OTP)
The over-temperature circuit limits the junction tempera-
ture of the APW7303. When the junction temperature ex-
ceeds TJ = +160oC, a thermal sensor turns off the power
MOSFET, allowing the devices to cool. The thermal sen-
sor allows the converter to start a start-up process and
regulate the output voltage again after the junction tem-
perature cools by 50oC.
The OTP is designed with a 50oC hysteresis to lower the
average TJ during continuous thermal overload conditions,
increasing lifetime of the lC.
Enable / Shutdown
Driving EN to ground places the APW7303 in shutdown.
When in shutdown, the internal power MOSFET turns off,
all internal circuitry shuts down.
Current-Limit Protection
The APW7303 monitors the output current, flowing
through the N-Channel power MOSFET, and limits the
IC from damages during overload, short-circuit and over-
voltage conditions.
Frequency Foldback
The foldback frequency is controlled by the FB voltage.
When the FB pin voltage is under 0.6V, the frequency of
the oscillator will be reduced to 110kHz. This lower fre-
quency allows the inductor current to safely discharge,
thereby preventing current runaway. The oscillator’s fre-
quency will switch to its designed rate when the feedback
voltage on FB rises above the rising frequency foldback
threshold (0.6V, typical) again.
Soft-Start
The APW7303 provides the programmed soft-start func-
tion to limit the inrush current. The soft-start time can be
programmed by the external capacitor between SS and
GND. Typical charge current is 6µA, and the soft-start
time is 15ms with 0.1µF capacitor.
Boostrap Capacitor
The APW7303 is a N-channel MOSFET step down
converter. The MOSFET requires a gate voltage that is
higher than input voltage, thus a boost capacitor should
be connected between LX and BS pins to drive the gate of
the N-channel MOSFET. Typical boostrap capacitor value
is from 10nF to 100nF.
Copyright © ANPEC Electronics Corp.
Rev. A.4 - Nov., 2012
11
www.anpec.com.tw
Free Datasheet http://www.datasheetlist.com/
11 Page | ||
| Páginas | Total 18 Páginas | |
| PDF Descargar | [ Datasheet APW7303.PDF ] | |
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