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PDF APW8811 Data sheet ( Hoja de datos )
| Número de pieza | APW8811 | |
| Descripción | System Power PWM Controller | |
| Fabricantes | ANPEC | |
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APW8811
System Power PWM Controller for Notebook Computers
Features
Simplified Application Circuit
• Wide Input Voltage Range from 6V to 25V
• Provide 4 Independent Outputs with ±1.5% Accu-
racy Over-Temperature
- PWM1 Controller with Adjustable (2V to 5.5V) Out-
put
- PWM2 Controller with Adjustable (2V to 5.5V) Out-
put
- 100mA Low Dropout Regulator (LDO5) with Fixed
5V Output
- 100mA Low Dropout Regulator (LDO3) with Fixed General Description
3.3V Output
• Excellent Line/Load Regulations about ±1.5% Over- The APW8811 integrates dual step-down, constant-on-
Temperature Range
time, synchronous PWM controllers (that drives dual N-
• ±1%, (±1.5%, 50µA) 2.0V Reference Voltage Output channel MOSFETs for each channel) and two low drop-
• Built-In POR Control Scheme Implemented
out regulators as well as various protections into a chip.
• Selectable Forced-PWM or Automatic PFM/PWM The PWM controllers step down high voltage of a battery
(with Selectable Ultrasonic Operation)
to generate low-voltage for NB applications. The output of
• Constant-On-Time Control Scheme with Frequency PWM1 and PWM2 can be adjusted from 2V to 5.5V by
Compensation for PWM Mode
setting a resistive voltage-divider from VOUTx to GND.
• Selectable Switching Frequency in PWM Mode
The linear regulators provide 5V and 3.3V output for
• Built-in Digital Soft-Start for PWM Outputs and Soft- standby power supply. The linear regulators provide up
Stop for PWM Outputs and LDO Outputs
to 100mA output current. When the PWMx output voltage
• Integrated Bootstrap Forward P-CH MOSFET
is higher than LDOx bypass threshold, the related LDOx
• High Efficiency over Light to Full Load Range regulator is shut off and its output is connected to VOUTx
(PWMs)
by internal switchover MOSFET. It can save power
• Built-in Power Good Indicators (PWMs)
dissipation.
• Independent Enable Inputs (PWMs, LDO)
The APW8811 provides excellent transient response and
• 70% Under-Voltage and 125% Over-Voltage Protec- accurate DC output voltage in either PFM or PWM Mode.
tions (PWM)
• Adjustable Current-Limit Protection (PWMs)
In Pulse-Frequency Mode (PFM), the APW8811 provides
very high efficiency over light to heavy loads with loading-
- Using Sense Low-Side MOSFET’s RDS(ON)
• Over-Temperature Protection
modulated switching frequencies. The Forced-PWM
mode works nearly at constant frequency for low-noise
• 4mmx4mm Thin QFN-24 (TQFN4x4-24A) package requirements. The unique ultrasonic mode maintains the
• Lead Free and Green Device Available (RoHS switching frequency above 25KHz, which eliminates
Compliant)
noise in audio applications.
The APW8811 is equipped with accurate sourcing cur-
rent-limit, output under-voltage and output over-voltage
protections, being perfect for NB applications. A 1.7ms
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.3 - Sep., 20121
1
www.anpec.com.tw
Free Datasheet http://www.datasheet4u.com/
1 page  
APW8811
Electrical Characteristics (Cont.)
Refer to the typical application circuits. These specifications apply over VIN=12V and TA= -40 ~ 85 °C, unless otherwise
specified. Typical values are at TA=25°C.
Symbol
Parameter
Test Conditions
APW8811
Min.
Typ.
Max.
Unit
PWM CONTROLLERS (CONT.)
UGATEx Minimum On-Time
80 110 140 ns
Minimum Ultrasonic SKIP Operating
Frequency
25 37
- kHz
LOW DROUPUT LINEAR REGULATORS (LDO5/LDO3)
LDO5 Output Voltage
LDO3 Output Voltage
VTHBYP5
LDO5 Bypass Threshold for
VOUT1-to-LDO5 Switch On
VOUT1 = GND, 6V < VIN < 25V, 0<
ILDO < 100mA
VOUT2 = GND, 6V < VIN < 25V, 0<
ILDO3 < 100mA
VOUT1 Regulation Voltage Rising
Hysteresis
4.8
3.2
4.55
0.15
5.0
3.33
4.7
0.25
5.2
3.46
4.85
0.3
V
V
V
VTHBYP3
LDO3 Bypass Threshold for
VOUT2-to-LDO3 Switch On
VOUT2 Regulation Voltage Rising 3.05 3.15 3.25
V
Hysteresis
0.1 0.2 0.25
VOUTx-to-LDOx Switch On Resistance VOUTx to LDOx, 10mA
- 1.5 3 Ω
LDOx Current-Limit
VOUTx = GND, LDOx = GND
150 -
- mA
LDOx Discharge On Resistance
- 40 65 Ω
REFFERENCE
REF Output Voltage
IREF = 0A
1.98
2.00
2.02
V
REF Load Regulation
REF Sink Current
ILOAD = 0 to 50µA
REF in Regulation
- 10
10 -
- mV
- µA
PWM 1/2 PROTECTIONS
Over-Voltage Protection Threshold
Over-Voltage Fault Propagation Delay
Current-Limit Current Source
VOUTX RIsing
Delta voltage = 10mV
VILIM = 920mV, TA = 25oC
On the basis of 25 oC
120 125 130 %
- 1.5 - µs
9.4
10
10.6
µA
- 4500 2 ppm/ oC
ILIMx Adjustment Range
Maximum setting voltage
VILIMx-GND
VILIMx= 5V, Setting Current-Limit
Threshold
0.515
205
-
250
2V
- mV
Current-limit comparator offset
(VILIMx-GND-VPGND-PHASEx), VILIMx = 920mV
-8
0
8 mV
Zero-Crossing Threshold
SKIP# = REF or LDOx, VPGND-PHASE
-5
0
5 mV
Under-Voltage Protection Threshold
65 70 75 %
Under-Voltage Protection Hysteresis
- 3 -%
Under-Voltage Protection Debounce
Interval
22 32 42 µs
Under-Voltage Protection Enable
Blanking Time
From EN signal go high to UVP
workable
-
2 2.6 ms
TJ Rising
Over-Temperature Protection THreshold
Hysteresis
- 160 -
oC
- 25 -
Copyright © ANPEC Electronics Corp.
Rev. A.3 - Sep., 2012
5
www.anpec.com.tw
Free Datasheet http://www.datasheet4u.com/
5 Page 
APW8811
Function Description
Constant-On-Time PWM Controller with Input Feed-For-
ward
The constant-on-time control architecture is a pseudo-
fixed frequency with input voltage feed-forward. This ar-
chitecture relies on the output filter capacitor’s effective
series resistance (ESR) to act as a current-sense resistor,
so the output ripple voltage provides the PWM ramp signal.
In PFM operation, the high-side switch on-time controlled
by the on-time generator is determined solely by a one-
shot whose pulse width is inversely proportional to input
voltage and directly proportional to output voltage. In PWM
operation, the high-side switch on-time is determined by
a switching frequency control circuit in the on-time gen-
erator block. The switching frequency control circuit
senses the switching frequency of the high-side switch
and keeps regulating it at a constant frequency in PWM
mode. The design improves the frequency variation and
is more outstanding than a conventional constant-on-
time controller, which has large switching frequency varia-
tion over input voltage, output current and temperature.
Both in PFM and PWM, the on-time generator, which
senses input voltage on VIN pin, provides very fast on-
time response to input line transients.
Another one-shot sets a minimum off-time (typ.: 300ns).
The on-time one-shot is triggered if the error comparator
is high, the low-side switch current is below the current-
limit threshold, and the minimum off-time one-shot has
timed out.
Pulse-Frequency Modulation (PFM) Mode
Connect SKIP# to GND for normal PFM operation. In PFM
mode, an automatic switchover to pulse-frequency modu-
lation (PFM) takes place at light loads. This switchover is
affected by a comparator that truncates the low-side
switch on-time at the inductor current zero crossing. This
mechanism causes the threshold between PFM and
PWM operation to coincide with the boundary between
continuous and discontinuous inductor-current operation
(also known as the critical conduction point). The on-
time of PFM is given by:
TON - PFM
=1
FSW
× VOUT
VIN
Where FSW is the nominal switching frequency of the con-
verter in PWM mode. Similarly, the on-time of ultrasonic
mode is the same with PFM mode. The description of
ultrasonic mode will be illustrated later.
The load current at handoff from PFM to PWM mode is
given by:
ILOAD(PFM to PWM)
=
1×
2
VIN
− VOUT
L
× TON−PFM
= VIN − VOUT × 1 × VOUT
2L
FSW
VIN
Forced-PWM Mode
Connect SKIP# to REF for normal Forced-PWM operation.
The Forced-PWM mode disables the zero-crossing
comparator, which truncates the low-side switch on-time
at the inductor current zero crossing. This causes the
low-side gate-drive waveform to become the complement
of the high-side gate-drive waveform. This in turn causes
the inductor current to reverse at light loads while UGATE
maintains a duty factor of V /V . The benefit of Forced-
OUT IN
PWM mode is to keep the switching frequency fairly
constant. The Forced-PWM mode is the most useful for
reducing audio frequency noise, improving load-transient
response, and providing sink-current capability for dy-
namic output voltage adjustment.
Ultrasonic Mode
Connecting SKIP# to LDO3 or LDO5 for ultrasonic mode.
The ultrasonic mode activates a unique PFM mode with
a minimum switching frequency of 37kHz. The minimum
frequency 37KHz of ultrasonic mode eliminates audio-
frequency interference in light load condition. It will transit
to unique PFM mode when output loading makes the
frequency bigger than ultrasonic frequency. In ultrasonic
mode, the controller automatically transits to fixed-fre-
quency PWM operation when the load reaches the same
critical conduction point (ILOAD(PFM to PWM)).
When the controller detects that no switching has oc-
curred within about 27µs (typ.), an ultrasonic pulse will
occurre. The ultrasonic controller turns on the low-side
MOSFET first to reduce the output voltage. After feedback
voltage drops below the internal reference voltage, the
Copyright © ANPEC Electronics Corp.
Rev. A.3 - Sep., 2012
11
www.anpec.com.tw
Free Datasheet http://www.datasheet4u.com/
11 Page | ||
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| PDF Descargar | [ Datasheet APW8811.PDF ] | |
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