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PDF ISL6731B Data sheet ( Hoja de datos )
| Número de pieza | ISL6731B | |
| Descripción | Power Factor Correction Controllers | |
| Fabricantes | Intersil | |
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DATASHEET
Power Factor Correction Controllers
ISL6731A, ISL6731B
The ISL6731A and ISL6731B are active power factor
correction (PFC) controller ICs that use a boost topology. The
controllers are suitable for AC/DC power systems up to 2kW
and over the universal line input.
The ISL6731A and ISL6731B operate in Continuous Current
Mode (CCM). Accurate input current shaping is achieved with a
current error amplifier. A patent pending breakthrough
negative capacitance technology minimizes zero crossing
distortion and reduces the magnetic components size. The
small external components result in lower design cost without
sacrificing performance.
The internally clamped 12.5V gate driver delivers 1.5A peak
current to the external power MOSFET. The ISL6731A and
ISL6731B provide a highly reliable system that is fully
protected. Protection features include cycle-by-cycle
overcurrent, over power limit, over-temperature, input
brownout, output overvoltage and undervoltage protection.
The ISL6731A and ISL6731B provide excellent power
efficiency and transitions into a power saving skip mode
during light load conditions, thus improving efficiency
automatically. The ISL6731A and ISL6731B can be shut down
by pulling the FB pin below 0.5V or grounding the BO pin.
Two switching frequency options are provided. The ISL6731B
switches at 62kHz, and the ISL6731A switches at 124kHz.
Related Literature
• AN1884, "ISL6731AEVAL1Z and ISL6731BEVAL1Z: Boost
CCM PFC for 300W Universal Input Adaptors"
• AN1885, “ISL6731AEVAL2Z and ISL6731BEVAL2Z: High
Performance Boost CCM PFC Front End for Server Power
Applications”
Features
• Reduced component size requirements
- Enables smaller, thinner AC/DC adapters
- Choke and cap size can be reduced
- Lower cost of materials
• Excellent power factor and THD over line and load
- CCM mode with negative capacitance generator for
smaller EMI filter and improved performance
- Built-in current amplifier with flexibility of gain change
• Better light-load efficiency
- Automatic pulse skipping with programmable threshold
- Programmable or automatic shutdown
• Highly reliable design
- Cycle-by-cycle current limit
- Input average power limit
- OVP and OTP protection
- Input brownout protection
• Small 14 Ld SOIC package
Applications
• Desktop computer AC/DC adaptor
• Laptop computer AC/DC adaptor
• TV AC/DC power supply
• AC/DC brick converters
VLINE
VI
+ VOUT
VCC
ISEN
GATE
ICOMP
OVP
VIN ISL6731A FB
GND
COMP
BO SKIP VREG
FIGURE 1. TYPICAL APPLICATION
100
95
90
85
80
75
70
65
60
0
ISL6731A, SKIP
ISL6731A, NON-SKIP
20 40 60
OUTPUT POWER (%)
FIGURE 2. PFC EFFICIENCY
80
100
February 13, 2015
FN8582.1
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774 | Copyright Intersil Americas LLC 2014, 2015. All Rights Reserved
Intersil (and design) is a trademark owned by Intersil Corporation or one of its subsidiaries.
All other trademarks mentioned are the property of their respective owners.
1 page  
Application Schematics
Typical 300W Application Schematic
P1 AC1
F1 8A
UNIVERSAL INPUT C2
90~265Vac
470n
P4 AC2
PE
P5
L4
2.2m
2.2n 2.2n
C35 C36
D1
R1
L2
L1 1.5m
0u
IN5406
D2 2
C3D04060A
SPP20N60C3
1
DC+
VOUT
TP9
P2
L3
2.2m
2M
C22
R3 470n
2M
DB1
GBU806
RV1
MOV /DNP
C3
680n
R28 0.22
R27 0.22
TP12
GATE1
R2
2.2
Q1
1
R4
51k
C19
C1 0.1
390V
270u
C21 450V
0.1
P3
2.2n 2.2n
R5 0.22
C5 C6
D8 D7
S1M S1M
R8
470k
C12
DNP
R11
470k
VIN
TP3
R13
5.76k
C8
220n
DZ1
3.3V
R23
C7
1u
C11
1n
R14
30k
6.8n
C10
47n
C20
DNP
VREGTP8
C9
1u
VCC
U1
VREG Lin.Reg. VCC
TP7
DNP
GATE
GATE 14
3.3M
R24
3.3M
R9
3k
TP6
ICOMP
TP5 ISEN
4 ICOMP
3
I MIRROR
ISEN 2:1
I*Vin*C
gmI*= 4*BO*BO
UVLO LOGIC
CEQ OTP
Gen
PWM
GND 2
OVP 7
C23
5 VIN
+
C SKIP OPL
2.5V 1n
gm FB 9
C13
47p
VCC
-
BO
SKIP
COMP
ISL6731A/B
3.3M
R6
R10
3.3M
DNP
TP11
OVP
42.2k
R25
GND
TP10
C26
2.2n
R26
49.9
TP1 FB
VCC
GND
P6
P7
R17
0
DNP P8
R21
25k
DNP
1
2N7002
Q2
DNP
TP4
69.8K
R22
BO
TP2
COMP
C16
100n
R19
42.2k
R18 C15
DNP
R20
10k
C17
1n
DNP
C14
470n
62k
C18
150n
DNP P9
1u
5 Page 
ISL6731A, ISL6731B
Functional Description
VCC Undervoltage Lockout (UVLO)
The ISL6731A and ISL6731B start automatically once the
voltage at VCC exceeds the UVLO threshold.
Shutdown
When the VFB pin is below 0.2V, the controller is disabled and
the PWM output driver is tri-stated. When disabled, the IC power
will be reduced. During shutdown, the COMP pin is discharged to
GND and the controller is disabled. The Over-Temperature
Protection (OTP) is still alive to prevent the controller from
starting up in a high temperature ambient condition.
In the event that the FB pin is disconnected from the feedback
resistors, the FB pin is pulled to ground by an internal current
source IFB. When the FB pin voltage drops below 0.2V, the gate
driver is disabled. The ISL6731A or ISL6731B enters shutdown
mode.
Soft-Start
The COMP pin is released once the soft-start operation begins. A
13µA current sources out to the RC network connected from the
COMP pin until the FB pin voltage reaches 90% of the reference
voltage.
Switching is inhibited when the COMP pin voltage is below 1V.
When the COMP pin reaches 1V, the current error amplifier and
the gate driver are activated and the converter starts switching.
During UVLO, brownout and shutdown, the COMP is pulled to the
ground.
Input Voltage Sensing
The VIN pin is needed to sense the rectified input voltage. The
sensed semi-sinusoidal waveform is needed to shape the
inductor current, which helps achieves unity power factor. At the
same time, the voltage on the VIN pin is used to generate the
negative capacitive element at the input. This will cancel the
input filter capacitor, CF. Canceling the effect of CF will increase
the displacement power factor and alleviate the zero crossing
distortion, which is related to the distortion power factor.
EMI CHOKE
VLINE
CF3
DF1
DF2
RIN2
Lm
VIN
RIN1
BO
CBO
CF2
FIGURE 10. INPUT VOLTAGE SENSING SCHEMATIC
The BO pin also utilizes the VIN resistor divider for voltage
sensing. Set the resistor divider ratio to satisfy the brownout
requirement.
First, calculate the resistor divider ratio, KBO.
KBO = V-----R---V-M---B--S--O--m--R--i--n-M---–-A----2X----V----F--
(EQ. 1)
Where VF is the forward voltage drop of the bridge rectifier and
the voltage drop of DF1; DF2.
Then, select the RIN2 based on the highest reasonable resistance
value. Then select the RIN1 based upon the desirable minimum
RMS value of the line voltage for the PFC operation.
RIN1 = 1-----K–----B-K---O-B----O-- RIN2
(EQ. 2)
Inductor Current Sensing
The current sensing of the converter has two purposes. One is to
force the inductor current to track the input semi-sinusoidal
waveform. The other purpose is for overcurrent protection. Refer to
Figure 11 for the current sensing scheme. The sensed current ICS
is in proportion to the inductor current, IL as described in
Equation 3:
ICS = 12-- R--R---S--C--E--S--N-- IL
(EQ. 3)
where:
RCS is the current sensing resistor with low value in the return
path to the bridge rectifier.
RSEN is the current scaling resistor connected between ISEN to
the RCS.
VI
L
VOUT
Q1 COUT
CF1
RCS
RSEN
CURRENT
MIRROR
2:1 ICS
ISEN
ICS > 0.5 IOC
FIGURE 11. INDUCTOR CURRENT SENSING SCHEME
A high value RCS renders more accurate current sensing. It is
recommended to use the RCS to render 120mV peak voltage at
the maximum line voltage during full load condition.
RC
S
-1---2---0----m-----V---------V----R----M-----S----M-----A----X----------
2 POmax
(EQ. 4)
Where is the efficiency of the converter at the maximum line
input with full load.
Submit Document Feedback 11
FN8582.1
February 13, 2015
11 Page | ||
| Páginas | Total 20 Páginas | |
| PDF Descargar | [ Datasheet ISL6731B.PDF ] | |
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