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PDF APW8804 Data sheet ( Hoja de datos )
| Número de pieza | APW8804 | |
| Descripción | 3A 5V 1MHz Synchronous Buck Converter | |
| Fabricantes | ANPEC | |
| Logotipo |  |
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APW8804
3A 5V 1MHz Synchronous Buck Converter
Features
General Description
• High Efficiency up to 95%
APW8804 is a 3A synchronous buck converter with inte-
- Automatic PFM/PWM Mode Operation
grated 65mΩ high side and 55mΩ low side power
•
Adjustable Output Voltage from 0.6V to V
PVDD
MOSFETs. The APW8804, design with a current-mode
• Integrated 65mΩ High Side / 55mΩ Low Side control scheme, can convert wide input voltage of 2.6V to
MOSFETs
• Low Dropout Operation: 100% Duty Cycle
• Stable with Low ESR Ceramic Capacitors
• Power-On-Reset Detection on VDD and PVDD
6V to the output voltage adjustable from 0.6V to 6V to
provide excellent output voltage regulation.
The APW8804 is equipped with an automatic PFM/PWM
mode operation. At light load , the IC operates in the PFM
mode to reduce the switching losses. At heavy load, the
• Integrated Soft-Start and Soft-Stop
IC works in PWM mode. At PWM mode, the switching
• Over-Temperature Protection
frequency is set by the external resistor.
• Over-Voltage Protection
The APW8804 is also equipped with Power-on-reset, soft-
• Under-Voltage Protection
• High/ Low Side Current Limit
• Power Good Indication
• Enable/Shutdown Function
• Small TDFN3x3-10 and SOP-8P Packages
• Lead Free and Green Devices Available
start, soft-stop, and whole protections (under-voltage,
over-voltage, over-temperature and current-limit) into a
single package.
This device, available TDFN3x3-10 and SOP-8P, provides
a very compact system solution external components and
PCB area.
(RoHS Compliant)
Simplified Application Circuit
Applications
• Notebook Computer & UMPC
• LCD Monitor/TV
• Set-Top Box
• DSL, Switch HUBr
• Portable Instrument
VIN
ON
OFF
PVDD
LX
VDD FB
APW8804
POK
GND
EN
(option)
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 - Dec., 2012
1
www.anpec.com.tw
Free Datasheet http://www.datasheet4u.com/
1 page  
APW8804
Typical Operating Characteristics
Refer to the “Typical Application Circuit”. The test condition is VVDD=5V, TA= 25oC unless otherwise specified.
Efficiency vs. Load Current
100
Efficiency vs. Load Current
100
90 90
80
VVDD=5V
70
60
50
0
100
VOUT=3.3V
12
Load Current, IOUT(A)
Efficiency vs. Load Current
3
90
80
70
VVDD=5V
VVDD=3.3V
60
50
0
VOUT=1.05V
12
Load Current, IOUT(A)
3
Supply Voltage vs. P-FET Current
Limit
6
5
4
3
2
1
0
2 34 5
Supply Voltage, VVDD(V)
Copyright © ANPEC Electronics Corp.
Rev. A.4 - Dec., 2012
6
5
80
70 VVDD=5V
VVDD=3.3V
60
50
0
VOUT=1.8V
12
Load Current, IOUT(A)
3
Output Voltage vs. Load Current
1.9
1.88
1.86
1.84
1.82
1.8
1.78
1.76
1.74
1.72
1.7
0
0.5 1 1.5 2 2.5
Load Current, IOUT(A)
3
Supply Voltage vs. MOSFET On
Resistance
100
90
80
70
60
50
40
30 P-FET
N-FET
20
10
0
2 34 5
Supply Voltage, VVDD(V)
6
www.anpec.com.tw
Free Datasheet http://www.datasheet4u.com/
5 Page 
APW8804
Function Description
VDD and PVDD Power-On-Reset (POR)
The APW8804 keeps monitoring the voltage on VDD and
PVDD pins to prevent wrong logic operations which may
occur when VDD or PVDD voltage is not high enough for
internal control circuitry to operate. The VDD POR rising
threshold is 2.4V (typical) with 0.2V hysteresis and PVDD
POR rising threshold is 1.7V with 0.2V hysteresis.
During start-up, the VDD and PVDD voltage must exceed
the enable voltage threshold. Then, the IC starts a start-
up process and ramps up the output voltage to the volt-
age target.
Output Under-Voltage Protection (UVP)
In the operational process, if a short-circuit occurs, the
output voltage will drop quickly. Before the current-limit
circuit responds, the output voltage will fall out of the re-
quired regulation range. The under-voltage continually
monitors the FB voltage after soft-start is completed. If a
load step is strong enough to pull the output voltage lower
than the under-voltage threshold, the IC starts soft-stop
function and shuts down converter’s output.
The under-voltage threshold is 50% of the nominal out-
put voltage. The under-voltage comparator has a built-in
3µs noise filter to prevent the chips from wrong UVP shut-
down being caused by noise. APW8804 will be latched
after under-voltage protection.
Over-Voltage Protection (OVP)
The over-voltage function monitors the output voltage by
FB pin. When the FB voltage increases over 125% of the
reference voltage due to the high-side MOSFET failure or
for other reasons, the over-voltage protection comparator
will trigger soft-stop function and shutdown the converter
output.
Over-Temperature Protection (OTP)
The over-temperature circuit limits the junction tempera-
ture of the APW8804. When the junction temperature ex-
ceeds TJ=+160oC, a thermal sensor turns off the both
power MOSFETs, allowing the devices to cool. The ther-
mal sensor allows the converters to start a start-up pro-
cess and to regulate the output voltage again after the
junction temperature cools by 50oC. The OTP is designed
with a 50oC hysteresis to lower the average TJ during
continuous thermal overload conditions, increasing life-
time of the APW8804.
Current-Limit Protection
The APW8804 monitors the output current, flows through
the high-side and low-side power MOSFETs, and limits
the current peak at current-limit level to prevent the IC
from damaging during overload, short-circuit and over-
voltage conditions. Typical high side power MOSFET cur-
rent limit is 4.5A, and low side MOSFET current limit is
1.9A.
Soft-Start
The APW8804 has a built-in soft-start to control the rise
rate of the output voltage and limit the input current surge
during start-up. During soft-start, an internal voltage ramp
connected to one of the positive inputs of the error
amplifier, rises up to replace the reference voltage (0.6V)
until the voltage ramp reaches the reference voltage. Dur-
ing soft-start without output over-voltage, the APW8804
converter’s sinking capability is disabled until the output
voltage reaches the voltage target.
Soft-Stop
At the moment of shutdown controlled by EN signal, un-
der-voltage event or over-voltage event, the APW8804 ini-
tiates a soft-stop process to discharge the output voltage
in the output capacitors. Certainly, the load current also
discharges the output voltage. During soft-stop, the inter-
nal voltage ramp (V ) falls down to replace the refer-
RAMP
ence voltage. The low side MOSFET turns on each cycle
to discharge the output voltage. Therefore, the output volt-
age falls down slowly at the light load. After the soft-stop
interval elapses, the soft-stop process ends and the IC
turns off.
Enable and Shutdown
Driving EN to ground places the APW8804 in shutdown.
In shutdown mode, the internal N-Channel power
MOSFET turns off, all internal circuitry shuts down and
the quiescent supply current reduces to less than 1µA.
Copyright © ANPEC Electronics Corp.
Rev. A.4 - Dec., 2012
11
www.anpec.com.tw
Free Datasheet http://www.datasheet4u.com/
11 Page | ||
| Páginas | Total 21 Páginas | |
| PDF Descargar | [ Datasheet APW8804.PDF ] | |
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