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PDF APW8715 Data sheet ( Hoja de datos )
| Número de pieza | APW8715 | |
| Descripción | High Input Voltage 6A PWM Converter | |
| Fabricantes | ANPEC | |
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APW8715
High Input Voltage 6A PWM Converter With Adj. Soft Start
Features
General Description
• Adjustable Output Voltage from +0.8V to +12V
- 0.8V Reference Voltage
- +1% Accuracy over Temperature
The APW8715 is a 6A, synchronous, step-down converter
with integrated 30mΩ N-channel High-Side MOSFET and
12mΩ Low-Side MOSFET. The APW8715 steps down
• Operates from An Input Battery Voltage Range of high voltage to generate low-voltage chipset or RAM sup-
+2.7V to +28V
plies in notebook computers.
• Power-On-Reset Monitoring on VCC pin
The APW8715 provides excellent transient response and
• Excellent line and load transient responses
accurate DC voltage output in either PFM or PWM Mode.
• PFM mode for increased light load efficiency
In Pulse Frequency Mode (PFM), the APW8715 provides
very high efficiency over light to heavy loads with loading-
• Programmable PWM Frequency from 100kHz to modulated switching frequencies. In PWM Mode, the con-
1000kHz
verter works nearly at constant frequency for low-noise
• Integrated 30mΩ at VCC=5V N-Channel MOSFET requirements.
For High Side
The APW8715 is equipped with accurate current-limit, out-
• Integrated 12mΩ at VCC=5V N-Channel MOSFET put under-voltage, and output over-voltage protections,
For Low Side
perfect for various applications. A Power-On-Reset func-
• Integrated Bootstrap Forward P-CH MOSFET
tion monitors the voltage on VCC to prevent wrong
• External Adjustable Soft-Start and Soft-Stop
operation during power-on. The APW8715 has external
•
adjustable soft-start and built-in an integrated output dis-
Selectable Forced PWM or automatic PFM/PWM
charge method for soft stop. A soft-start ramps up the
mode
output voltage with programmable timing to reduce the
• Power Good Monitoring
start-up current. A soft-stop function actively discharges
• 70% Under-Voltage Protection
the output capacitors.
• 125% Over-Voltage Protection
The APW8715 is available in TQFN4x4-23 (Power PAK).
• Current-Limit Protection
- Using Sense Low-Side MOSFET’s RDS(ON)
• Over-Temperature Protection
Applications
• TQFN-23 4mmx4mm package
• Lead Free and Green Device Available (RoHS
Compliant)
• Notebook
• Mother Board
• Table PC
• Hand-Held Portable
• AIO PC
• Set-top boxes
• LCD TV
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.5 - Apr., 2016
1
www.anpec.com.tw
1 page  
APW8715
Electrical Characteristics
Unless otherwise specified, these specifications apply over VIN=12V,VEN=5V and TA= -40 to 85 oC. Typical values are at TA=25oC.
Symbol
Parameter
POWER-OK INDICATOR
VPOK
POK Threshold
IPOK POK Leakage Current
POK Sink Current
POK Out Debounce Time2
POK Enable Delay Time
CURRENT SENSE
IOCP OCP Threshold
Zero Crossing Comparator
Offset
PROTECTION
VUV UVP Threshold
UVP Debounce Interval
UVP Enable Delay
VOVR
OVP Rising Threshold1
OVP Propagation Delay
TOTR
OTP Rising Threshold (Note
5)
OTP Hysteresis (Note 5)
Test Condition
POK in from Lower (POK Goes
High)
POK out from Normal (POK Goes
Low)
VPOK=5V
VPOK=0.5V，
When run away 90%
From EN High to POK High
Valley Current of IL
VGND-LX Voltage, PFM=0V
EN high to UVP workable
OVP Occur
VFB Rising, Over Voltage=10mV
Min.
APW8715
Typ. Max.
Unit
87 90 93 %
120 125 130 %
-
1.25
-
-
0.1
7.5
20
Tss
- µA
- mA
- µs
- ms
7 - -A
-5 0 5 mV
65 70 75 %
16 µs
Tss ms
120 125 130 %
- 3 - µs
- 145 - oC
- 45 - oC
Copyright © ANPEC Electronics Corp.
Rev. A.5 - Apr., 2016
5
www.anpec.com.tw
5 Page 
APW8715
Function Description (Cont.)
Soft-Start
The APW8715 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 10uA, and the soft-start
time can be calculated by the following formula:
TSS(µs) = 330 × CSS(nF)
The APW8715 integrates soft-start circuits to ramp up the
output voltage of the converter to the programmed regu-
lation set point at a predictable slew rate. The slew
rate of output voltage is internally controlled to limit the
inrush current through the output capacitors during soft-
start process. When the EN pin is pulled above the rising
EN threshold voltage, the device initiates a soft-start pro-
cess to ramp up the output voltage.
During soft-start stage before the PGOOD pin is ready,
the under voltage protection is prohibited. The over volt-
age and current limit protection functions are enabled. If
the output capacitor has residue voltage before startup,
both low-side and high-side MOSFETs are in off-state
until the soft start voltage equal the V voltage. This will
FB
ensure the output voltage starts from its existing voltage
level.
In the event of under-voltage, over-voltage, over-tempera-
ture or shutdown, the chip enables the soft-stop function.
The soft-stop function discharges the output voltages by
low side turns MOSFET on linearly.
Power Good Indicator
POK is actively held low in shutdown and soft-start status.
In the soft-start process, the POK is an open-drain. When
the soft-start is finished, the POK is released. In normal
operation, the POK window is from 90% to 125% of the
converter reference voltage. When the output voltage has
to stay within this window, POK signal will become high.
When the output voltage outruns 90% or 125% of the
target voltage, POK signal will be pulled low immediately.
In order to prevent false POK drop, capacitors need to
parallel at the output to confine the voltage deviation with
severe load step transient.
Under-Voltage Protection (UVP)
In the process of operation, if a short circuit occurs, the
output voltage will drop quickly. When load current is big-
ger than current limit threshold value, the output voltage
will fall out of the required regulation range. The under-
voltage protection circuit continually monitors the FB volt-
age after soft-start is completed. If a load step is strong
enough to pull the output voltage lower than the under
voltage threshold, the under voltage threshold is 70% of
the nominal output voltage, the internal UVP delay counter
starts to count. After 16ms de-bounce time, the device
turns off both high side and low-side MOSEFET with
latched. Toggling enable pin to low, or recycling VIN, will
clear the latch and bring the chip back to operation.
Over-Voltage Protection (OVP)
The over voltage function monitors the output voltage by
FB pin. Should the FB voltage increase over 125% of the
reference voltage due to the high-side MOSFET failure or
for other reasons, the over voltage protection comparator
designed with a 3µs noise filter will force the low-side
MOSFET gate driver fully turn on and latch high. This ac-
tion actively pulls down the output voltage.
This OVP scheme only clamps the voltage overshoot,
and does not invert the output voltage when otherwise
activated with a continuously high output from low-side
MOSFET driver. It’s a common problem for OVP schemes
with a latch. Once an over-voltage fault condition is set, it
can only be reset by toggling EN or VIN power-on-reset
signal.
Current Limit
The current limit circuit employs a "valley" current-sens-
ing algorithm (See Figure 1). The APW8715 uses the
low-side MOSFET’s R of the synchronous rectifier
DS(ON)
as a current-sensing element. If the magnitude of the
current-sense signal at LX pin is above the current-limit
threshold 7A(minimum), the PWM is not allowed to ini-
tiate a new cycle. The actual peak current is greater than
the current-limit threshold by an amount equal to the in-
ductor ripple current. Therefore, the exact current-limit char-
acteristic and maximum load capability are a function of
the sense resistance, inductor value, and input voltage.
Copyright © ANPEC Electronics Corp.
Rev. A.5 - Apr., 2016
11
www.anpec.com.tw
11 Page | ||
| Páginas | Total 20 Páginas | |
| PDF Descargar | [ Datasheet APW8715.PDF ] | |
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