LT8312 - Boost Controller with Power Factor Correction

LT8312
Boost Controller with
Power Factor Correction
Features
Description
PFC Boost with Minimum Number of External Components
nn V and V
IN
OUT Limited Only by External Components
nn Active Power Factor Correction
nn Low Harmonic Distortion
nn Overvoltage Protection
nn Energy Star Compliant (<0.5W No-Load Operation)
nn 16-Lead MSOP Package
The LT®8312 is a power factor correction (PFC) boost
controller. A LT8312-based design can achieve a power
factor of greater than 0.99 by actively modulating the input
current, allowing compliance with most Harmonic Current
Emission requirements.
nn
The LT8312 is well suited for a wide variety of off-line
applications. The input range can be scaled up or down,
depending mainly on the choice of external components.
Efficiencies higher than 95% can be achieved with output
power levels up to 250W.
Applications
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
Industrial
nn Aviation
nn
Typical Application
Universal Input 200W PFC Boost Converter
B1
GBU404
0.1µF
499k
100k
•
10µF
499k
VOUT
400V
560µF 0.5A
×2
4.7pF
100k
D3
2k
1M
VIN_SENSE
FB
EN/UVLO
95.3k
9.53k
LT8312
GATE
VREF
SENSE
INTVCC
OVP
GND
100k
221k
VC
98
1M
DCM
VIN
1M
Efficiency
99
20Ω
97
EFFICIENCY (%)
90V
TO 265V
AC
•
D2 20Ω
D4
CMR5H-06
4:1
115VAC
96
95
230VAC 50Hz
94
93
4.7µF
92
0.01Ω
91
2.2µF
0
20
40
60 80 100 120 140 160
POWER (W)
8312 G01
8312 TA01a
8312fa
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1
LT8312
Absolute Maximum Ratings
(Note 1)
Pin Configuration
EN/UVLO....................................................................30V
VIN.............................................................................42V
INTVCC.......................................................................18V
FB................................................................................3V
VC................................................................................5V
VIN(SENSE).................................................................1mA
OVP..............................................................................4V
SENSE.......................................................................0.4V
DCM........................................................................±3mA
Operating Temperature Range (Note 2).....–40°C to 125°C
Storage Temperature Range................... –65°C to 150°C
TOP VIEW
GND
GND
GND
VREF
OVP
VC
GND
GND
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
VIN_SENSE
SENSE
GATE
INTVCC
EN/UVLO
VIN
DCM
FB
MS PACKAGE
16-LEAD PLASTIC MSOP
θJA = 125°C/W
Order Information
(http://www.linear.com/product/LT8312#orderinfo)
LEAD FREE FINISH
TAPE AND REEL
PART MARKING*
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LT8312EMS#PBF
LT8312EMS#TRPBF
8312
16-Lead Plastic MSOP
–40°C to 125°C
LT8312IMS#PBF
LT8312IMS#TRPBF
8312
16-Lead Plastic MSOP
–40°C to 125°C
LT8312HMS#PBF
LT8312HMS#TRPBF
8312
16-Lead Plastic MSOP
–40°C to 150°C
LT8312MPMS#PBF
LT8312MPMS#TRPBF
8312
16-Lead Plastic MSOP
–55°C to 150°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
Consult LTC Marketing for information on nonstandard lead based finish parts.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/
2
8312fa
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LT8312
Electrical Characteristics
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C.
PARAMETER
CONDITIONS
MIN
Input Voltage Range
TYP
MAX
38
V
60
70
70
µA
µA
10
45
UNITS
Quiescent Current
VEN/UVLO = 0.2V
Not Switching
VIN Quiescent Current, INTVCC Overdriven
VINTVCC = 11V
60
µA
VIN Shunt Regulator Voltage
I = 1mA
40
V
VIN Shunt Regulator Current Limit
8
INTVCC Quiescent Current
VEN/UVLO = 0.2V
VEN/UVLO = 1.5V, Not Switching
EN/UVLO Pin Threshold
EN/UVLO Pin Voltage Rising
EN/UVLO Pin Hysteresis Current
EN/UVLO = 1V
VREF Voltage
0µA Load
200µA Load
l
l
l
SENSE Current Limit Threshold
15.5
2.2
17.5
2.7
µA
mA
1.21
1.25
1.29
V
8
10
12
μA
1.97
1.95
2.0
1.98
2.03
2.03
V
V
96
102
107
Minimum SENSE Current Limit
SENSE Input Bias Current
mA
12.5
1.8
3
Current Out of Pin
15
Current Sense Blanking Time
FB Voltage
l
mV
mV
µA
90
130
170
ns
1.22
1.25
1.28
V
FB Voltage Line Regulation
10V < VIN < 35V
0.01
0.03
%/V
FB Pin Bias Current
(Note 3), FB = 1.25V, OVP = 1.35V
100
600
nA
FB Error Amplifier Voltage Gain
ΔVVC/ΔVFB
180
V/V
FB Error Amplifier Transconductance
ΔI = 5µA
170
µmhos
0.1
V
FB Low Detection Voltage
DCM Current Turn-On Threshold
Current Out of Pin
Maximum Oscillator Frequency
80
µA
400
kHz
Linear Regulator
INTVCC Regulation Voltage
9.8
Dropout (VIN-INTVCC)
IINTVCC = –10mA, VIN = 10V
Current Limit
INTVCC < 9.5V
INTVCC > 9.5V
12
80
10
10.4
V
500
900
mV
25
120
mA
mA
Gate Driver
tr GATE Driver Output Rise Time
CL = 3300pF
18
ns
tf GATE Driver Output Fall Time
CL = 3300pF
18
ns
GATE Output Low (VOL)
0.01
GATE Output High (VOH)
V
INTVCC –
50mV
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: The LT8312E is guaranteed to meet specified performance from
0°C to 125°C junction temperature. Specification over the –40°C and
125°C operating junction temperature range are assured by design,
characterization and correlation with statistical process controls. The
LT8312I is guaranteed to meet specified performance from –40°C to
V
125°C operating junction temperature range. The LT8312H is guaranteed
to meet performance specifications over the –40°C to 150°C operating
junction temperature range. The LT8312MP is guaranteed to meet
performance specifications over the –55°C to 150°C operating junction
temperature range. High junction temperatures degrade operating
lifetimes. Operating lifetime is derated for junction temperatures greater
than 125°C.
Note 3: Current flows out of the FB pin.
8312fa
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3
LT8312
Typical Performance Characteristics
EN/UVLO Threshold
vs Temperature
Input Voltage Hysteresis Current
vs Temperature
RISING
1.26
1.24
FALLING
1.22
1.2
–50 –25
0
11.5
11
40
20
10
2.05
0
0
–50 –25
25 50 75 100 125 150
TEMPERATURE (°C)
0
25 50 75 100 125 150
TEMPERATURE (°C)
8312 G03
SENSE Pin Threshold Current
vs Temperature
VREF vs VIN
120
2.04
SENSE CURRENT LIMIT (mV)
2.03
2.02
VIN = 24V WITH NO LOAD
2.000
1.975
VIN = 24V WITH 200µA LOAD
1.950
VREF (V)
VREF (V)
50
8312 G02
VREF vs Temperature
2.025
2.01
NO LOAD
2
1.99
200µA LOAD
1.98
1.97
1.925
MAX ILIM
100
80
60
40
20
1.96
1.900
–50 –25
0
25 50 75 100 125 150
TEMPERATURE (°C)
1.95
10
15
20
8312 G04
INTVCC vs Temperature
25
VIN (V)
30
VIN Shunt Voltage vs Temperature
42
10.2
25 50 75 100 125 150
TEMPERATURE (°C)
8312 G07
9
40
39.5
9.2
0
41
40.5
9.6
9.4
9.75
ISHUNT = 1mA
41.5
10
INTVCC (V)
10
25 50 75 100 125 150
TEMPERATURE (°C)
8312 G06
VIN SHUNT VOLTAGE (V)
NO LOAD
10mA LOAD
25mA LOAD
0
8312 G05
9.8
9.5
–50 –25
0
–50 –25
40
35
INTVCC vs VIN
10.25
INTVCC (V)
60
30
10.5
25 50 75 100 125 150
TEMPERATURE (°C)
2.050
4
VIN = 12V
70
10
–50 –25
2.075
10.5
VIN = 24V
80
8312 G01
2.100
VIN IQ vs Temperature
90
IQ (µA)
EN/UVLO HYSTERESIS CURRENT (µA)
1.28
EN/UVLO (V)
100
12
1.3
5
10
15
25
20
VIN (V)
30
40
35
39
–50 –25
0
25 50 75 100 125 150
TEMPERATURE (°C)
8312 G09
8312 G08
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LT8312
Typical Performance Characteristics
Maximum VIN Shunt Current
vs Temperature
THD vs Output Power
0.90
POWER FACTOR
40
THD
8
7
30
230VAC 50Hz
20
230VAC 50Hz
0.85
0.80
0.75
0.70
6
5
–50 –25
115VAC
0.95
50
9
SHUNT CURRENT (mA)
Power Factor vs Output Power
1.00
60
10
10
0
25 50 75 100 125 150
TEMPERATURE (°C)
0
0.65
115VAC
0
20
40
60 80 100 120 140 160
POWER (W)
8312 G11
8312 G10
0.60
0
20
40
60 80 100 120 140 160
POWER (W)
8312 G12
Pin Functions
GND (Pins 1, 2, 3, 7, 8): Ground.
VREF (Pin 4): Voltage Reference Output Pin, Typically
2V. This pin drives a resistor divider for the OVP pin. Can
supply up to 200μA.
OVP (Pin 5): Overvoltage Protection. This pin accepts a
DC voltage to compare to the voltage output information.
When FB pin voltage is above the OVP, the part stops
switching. This protects devices connected to the output.
VC (Pin 6): Compensation Pin for Internal Error Amplifier.
Connect a series RC from this pin to ground to compensate the switching regulator. A 100pF capacitor in parallel
helps eliminate noise.
FB (Pin 9): Voltage Loop Feedback Pin. FB is used to
regulate the output voltage.
DCM (Pin 10): Discontinuous Conduction Mode Detection
Pin. Connect a capacitor and resistor in series with this
pin to the auxiliary winding.
VIN (Pin 11): Input Voltage. This pin supplies current to
the internal start-up circuitry and to the INTVCC LDO. This
pin must be locally bypassed with a capacitor. A 42V shunt
regulator is internally connected to this pin.
EN/UVLO (Pin 12): Enable/Undervoltage Lockout. A resistor divider connected to VIN is tied to this pin to program
the minimum input voltage at which the LT8312 will turn
on. When below 1.25V, the part will draw 60μA with most
of the internal circuitry disabled and a 10μA hysteresis
current will be pulled out of the EN/UVLO pin. When above
1.25V, the part will be enabled and begin to switch and
the 10μA hysteresis current is turned off.
INTVCC (Pin 13): Regulated Supply for Internal Loads
and GATE Driver. Supplied from VIN and regulates to 10V
(typical). INTVCC must be bypassed with a 4.7μF capacitor
placed close to the pin.
GATE (Pin 14): N-Channel FET Gate Driver Output. Switches
between INTVCC and GND. Driven to GND during shutdown
state and stays high during low voltage states.
SENSE (Pin 15): The Current Sense Input for the Control
Loop. Kelvin connect this pin to the positive terminal of the
switch current sense resistor, RSENSE, in the source of the
NFET. The negative terminal of the current sense resistor
should be connected to the GND plane close to the IC.
VIN(SENSE) (Pin 16): Line Voltage Sense Pin. The pin is
used for sensing the AC line voltage to perform power
factor correction. Connect a resistor in series with the
line voltage to this pin.
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5
LT8312
Block Diagram
D2
R2
L2
C1
R1
L1
D1
10
12
16
EN/UVLO
DCM
4
VREF
VIN
VIN(SENSE)
R4
1.22V
Q1
–
+
–
+
ONE
SHOT
A2
–
V
600MV
+
6
VC
13
C5
A1
DRIVER
Q
MASTER
LATCH
–
INTVCC
R11
S
C4
M2
R10
S R
+
A7
CURRENT
COMPARATOR
A3
A8
R3
–
+
1.22V
C6
START-UP
INTERNAL REG
R9
FB
VOUT
11
5 OVP
9
VIN
C2
R14
R5
R8
C3
R13
A6
SENSE
A4
MULTIPLIER
GATE
14
M1
15
R6
GND
1, 2, 3, 7, 8
OSCILLATOR
8312 BD
6
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LT8312
Operation
The LT8312 is a power factor correction boost controller
IC. It provides high power factor and low harmonic distortion in applications with current mode control and critical
conduction mode.
Active power factor correction is becoming a requirement for offline power supplies. A power factor of one is
achieved if the current drawn is proportional to the input
voltage. The LT8312 modulates the peak current limit with
a scaled version of the input voltage. This technique can
provide power factors of 0.97 or greater.
The Block Diagram shows an overall view of the system.
The external components are in a boost topology configuration. The auxiliary winding supplies power to the part in
steady-state operation. The VIN pin supplies power to an
internal LDO that generates 10V at the INTVCC pin. The
control circuitry consists of an error amplifier, a multiplier,
a current comparator, and a master latch, which will be
explained in the following sections. A comparator is used
to detect discontinuous conduction mode (DCM) with a
cap connected to the auxiliary winding. The part features
a 1.9A gate driver.
a rate proportional to the difference between the output
voltage and the input voltage. When the current decreases
to zero, the output diode turns off and the voltage on the
drain of the MOSFET starts to oscillate from the parasitic
capacitance and the inductor. The auxiliary winding has
the same voltage across it as the main inductor and rings
too. The capacitor connected to the DCM pin, C1, trips the
comparator A2, which serves as a dv/dt detector, when
the ringing occurs. The dv/dt detector waits for the ringing
waveform to reach its minimum value and then the switch
turns back on. This switching behavior is similar to zero
volt switching and minimizes the amount of energy lost
when the switch is turned back on and improves efficiency
as much as 5%. Since this part operates on the edge of
continuous conduction mode and discontinuous conduction mode, the operating mode is called critical conduction
mode (or boundary conduction mode).
The output voltage is regulated with a resistor divider
connected to the FB pin. The output of the error amplifier
is the VC pin. This node needs a capacitor to compensate
the control loop.
The LT8312 is designed for off-line applications. The
EN/UVLO and a resistor divider are configured for a
micropower hysteretic start-up. In the Block Diagram, R2
is used to stand off the high voltage supply voltage. The
internal LDO starts to supply current to the INTVCC pin
when VIN is above 2.5V. The VIN and INTVCC capacitor
are charged by the current from R2. When VIN exceeds
the turn-on threshold and INTVCC is in regulation at 10V,
the part begins to switch. The VIN hysteresis is set by the
EN/UVLO resistor divider. The auxiliary winding provides
power to VIN when its voltage is higher than the VIN voltage. A voltage shunt is provided for fault protection and
can sink 8mA of current when VIN is over 40V.
Power Factor Correction
During a typical cycle, the gate driver turns the external
MOSFET on and a current flows through the inductor.
This current increases at a rate proportional to the input
voltage. The control loop determines the maximum current
and the current comparator turns the switch off when the
current level is reached. When the switch turns off, the
inductor current begins to flow through the diode connected to the output capacitor. This current decreases at
The LT8312 uses a hysteretic start-up to operate from
high offline voltages. A resistor connected to the supply
voltage protects the part from high voltages. This resistor
is connected to the VIN pin on the part and bypassed with
a capacitor. When the resistor charges the VIN pin to a
turn-on voltage set with the EN/UVLO resistor divider and
the INTVCC pin is at its regulation point, the part begins to
switch. The resistor cannot provide power for the part in
When the VIN(SENSE) pin is connected to the supply voltage with a resistor, the current limit is proportional to the
supply voltage. If the LT8312 is configured with a fast
control loop, the VC pin would adjust to the changes of the
VIN(SENSE). The only way for the multiplier to function is
to set the control loop to be an order of magnitude slower
than the fundamental frequency of the VIN(SENSE) signal.
In an offline application, the fundamental frequency of
the supply voltage is 120Hz so the control loop unity gain
frequency needs to be set less than approximately 12Hz.
Start-Up
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7
LT8312
Operation
steady state, but relies on the capacitor to start up the part,
then the auxiliary winding begins to provide power to the
VIN pin along with the resistor. An internal voltage clamp
is attached to the VIN pin to prevent the resistor current
from allowing VIN to go above the absolute maximum
voltage of the pin. The internal clamp is set at 40V and is
capable of 8mA (typical) of current at room temperature.
Setting the VIN Turn-On and Turn-Off Voltages
A large voltage difference between the VIN turn-on voltage
and the VIN turn-off voltage is preferred to allow time for
the auxiliary winding to power the part. The EN/UVLO
sets these two voltages. The pin has a 10μA current sink
when the pins voltage is below 1.25V and 0μA when
above 1.25V. The VIN pin connects to a resistor divider
as shown in Figure 1.
The UVLO threshold for VIN rising is:
VIN(UVLO,RISING) =1.25V •
R1+R2
+10µA •R1
R2
The UVLO Threshold for VIN Falling is :
VIN(UVLO, FALLING) =1.25V •
R1+R2
R2
VIN
R1
EN/UVLO
LT8312
GND
R2
8312 F01
Figure 1. Undervoltage Lockout (UVLO)
8
Programming Output Voltage
The output voltage is set using a resistor divider from the
output capacitor to the FB pin. From the Block Diagram
the resistors R3 and R4 form a resistor divider from the
output capacitor. The output voltage equation is:
VOUT = VBG •
R3+R4
R5
The VBG voltage is equal to FB Voltage in Electrical Specification Table.
Setting VIN(SENSE) Resistor
The VIN(SENSE) resistor sets the current feeding the internal
multiplier that modulates the current limit for power factor
correction. At the maximum line voltage, VMAX, the current
is set to 360µA. Under this condition, the resistor value is
equal to (VMAX/360µA).
Critical Conduction Mode Operation
Critical conduction mode is a variable frequency switching
scheme that always returns the inductor current to zero
with every cycle. The DCM pin uses a fast current input
comparator in combination with a small capacitor to detect
dv/dt on the auxiliary winding. To eliminate false tripping,
a blanking time of 200ns is applied after the switch turns
off. The detector looks for 80μA of current through the
DCM pin due to falling voltage on the auxiliary winding
when the output diode turns off. This is not the optimal
time to turn the switch on because the switch voltage is still
close to VOUT and would waste all the energy stored in the
parasitic capacitance on the switch node. Discontinuous
ringing begins when the output diode current reaches zero
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LT8312
Operation
and the energy in the parasitic capacitance on the switch
node transfers to the input capacitor. This is a secondorder network composed of the parasitic capacitance on
the switch node and the main inductor. The minimum
voltage of the switch node during this discontinuous
ring is 2VIN-VOUT. The LT8312 turns the switch back on
at this time, during the discontinuous switch waveform,
by sensing when the slope of the switch waveform goes
from negative to positive using the dv/dt detector. This
switching technique may increase efficiency by 5%.
At low current limits, the frequency of critical conduction mode can become very high. The LT8312 features a
maximum frequency clamp of 400kHz. The part operates
in discontinuous conduction mode when the natural critical conduction mode frequency is higher than 400kHz.
Sense Resistor Selection
The resistor, RSENSE, between the source of the external
N-channel MOSFET and GND should be selected to provide
an adequate switch current to drive the application without
exceeding the current limit threshold.
Minimum Current Limit
The LT8312 features a minimum current limit of approximately 3% of the peak current limit. This helps improve
the harmonic distortion during the input supplies off-line
crossover period.
Universal Input
The LT8312 operates over the universal input voltage
range of 90V AC to 265V AC.
Loop Compensation
The feedback loop is a traditional gm error amplifier. The
loop crossover frequency is set much lower than twice
the line frequency for PFC to work properly. In a typical
application, the compensation capacitor is 1µF.
MOSFET and Diode Selection
With a strong 1.9A gate driver, the LT8312 can effectively
drive most high voltage MOSFETs. A low QG MOSFET is
recommended to maximize efficiency. In most applications,
the RDS(ON) should be chosen to limit the temperature rise
of the MOSFET. The drain of the MOSFET is stressed to
VOUT during the time the MOSFET is off and the diode is
conducting current.
The diode is stressed to VOUT when the switch is on. The
average current through the diode is equal to the load
current.
Discontinuous Mode Detection
The discontinuous mode detector uses AC-coupling to
detect the ringing on the auxiliary winding. A 22pF capacitor with a 30k resistor in series is recommended in
most designs.
Power Factor Correction/Harmonic Content
The LT8312 attains high power factor and low harmonic
content by making the peak current of the main power
switch proportional to the line voltage by using and internal
multiplier. A power factor of >0.97 is easily attainable for
most applications by following the design equations in
this data sheet. With proper design, LT8312 applications
can easily meet most harmonic standards.
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9
10
2
3
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1 2
Z1
C1
0.22µF
•
•1
4
L N
90-265VAC
J1
4
L1
15mH
F1
3.15A
2
3
B1
GBU404
C2
0.47µF
L4
300µH
C12
1µF
C13
1nF
R18
75k
R5
24.9k
1%
R4
11.8k
1%
R3
301k
1%
R7
150k
1%
1206
R2
499k
1%
1206
C3
100pF
R8
2.4M
1%
D1
BAV20W
R6
150k
1%
1206
R1
499k
1%
1206
3
2
1
5
4
12
16
11
VIN
C5
680nF
GND
R26
10k
1%
C14
4.7µF
6
GND
GND
INTVCC
SENSE
GATE
FB
GND
VC
LT8312
DCM
10
C6
4.7nF
GND
OVP
VREF
EN/UVLO
VIN_SENSE
+
C4
10µF, 50V
D2
BAV20W
D3
CMZ5934B
R9
47Ω
1206
7
8
13
15
14
9
R10
2k
6
R11
10Ω
1%
R13
1M
1206
C9
100pF
50V
R14
100Ω
Q1
IPA50R190CE
C15
100pF
L3
760802122
450µH
10:1
D4
1N4005
R19
0Ω
12
R12
9.53k
•
D6
1N4148W
•
C8
4.7µF
16V
INTVCC
C7
27pF
7
3
Universal Input 150W PFC Boost Converter
R15
0.015Ω
1206
R16
1M
1206
+
D5
CMR5H-06
C10
100µF
450V
R17
1M
1206
J2
+
–
8312 TA02
400V/0.375A
1
2
LT8312
Typical Applications
8312fa
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1 2
Z1
4
•1
C1
47nF
•
L1
27mH
4
L N
97~134VAC
400Hz
J1
F1
2.5A
2
3
B1
KBP204G
C12
100nF
L4
1mH
C12
220nF
C13
1nF
R18
75k
R5
24.9k
1%
R4
11.8k
1%
R3
301k
1%
R7
100k
1%
1206
R2
499k
1%
1206
C3
100pF
R8
2.4M
1%
D1
BAV20W
R6
100k
1%
1206
R1
499k
1%
1206
3
2
1
5
4
12
16
11
VIN
C5
27nF
R26
82.5k
1%
C14
470nF
6
GND
GND
GND
INTVCC
SENSE
GATE
FB
GND
VC
LT8312
DCM
10
C6
4.7nF
GND
OVP
VREF
EN/UVLO
VIN_SENSE
+
C4
10µF, 50V
D2
BAV20W
D3
CMZ5934B
R9
47Ω
1206
7
8
13
15
14
9
R10
2k
6
R11
10Ω
1%
R13
1M
1206
C9
100pF
50V
R14
100Ω
Q1
IPA50R190CE
C15
100pF
L3
760801130
750µH
D4
1N4005
R19
0Ω
12
R12
9.53k
•
D6
1N4148W
•
C8
4.7µF
16V
INTVCC
C7
27pF
7
3
Avionics Input 60W PFC Boost Converter
R15
0.04Ω
1206
R16
1M
1206
+
D5
CMR2U-06
C10
47µF
450V
R17
1M
1206
J2
+
–
8312 TA03
400V/0.15A
1
2
LT8312
Typical Applications
8312fa
11
LT8312
Package Description
Please refer to http://www.linear.com/product/LT8312#packaging for the most recent package drawings.
MS Package
16-Lead Plastic MSOP
(Reference LTC DWG # 05-08-1669 Rev A)
MS Package
16-Lead Plastic MSOP
(Reference LTC DWG # 05-08-1669 Rev A)
0.889 ±0.127
(.035 ±.005)
5.10
(.201)
MIN
3.20 – 3.45
(.126 – .136)
4.039 ±0.102
(.159 ±.004)
(NOTE 3)
0.50
(.0197)
BSC
0.305 ±0.038
(.0120 ±.0015)
TYP
RECOMMENDED SOLDER PAD LAYOUT
0.254
(.010)
DETAIL “A”
3.00 ±0.102
(.118 ±.004)
(NOTE 4)
4.90 ±0.152
(.193 ±.006)
0° – 6° TYP
0.280 ±0.076
(.011 ±.003)
REF
16151413121110 9
GAUGE PLANE
0.53 ±0.152
(.021 ±.006)
DETAIL “A”
0.18
(.007)
SEATING
PLANE
1.10
(.043)
MAX
0.17 – 0.27
(.007 – .011)
TYP
1234567 8
0.50
(.0197)
BSC
NOTE:
1. DIMENSIONS IN MILLIMETER/(INCH)
2. DRAWING NOT TO SCALE
3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS.
MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE
4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.
INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE
5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX
12
0.86
(.034)
REF
0.1016 ±0.0508
(.004 ±.002)
MSOP (MS16) 0213 REV A
8312fa
For more information www.linear.com/LT8312
LT8312
Revision History
REV
DATE
DESCRIPTION
A
2/16
Modified schematics.
PAGE NUMBER
1, 14
Changed minimum current limit for INTVCC.
3
Changed OVP pin description.
6
8312fa
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection
of its circuits
as described
herein will not infringe on existing patent rights.
For more
information
www.linear.com/LT8312
13
LT8312
Typical Application
Universal Input 200W PFC Boost Converter
90V
TO 265V
AC
0.1µF
499k
•
D2 20Ω
100k
VOUT
400V
560µF 0.5A
×2
•
10µF
499k
D4
4:1
4.7pF
100k
D3
2k
1M
VIN
1M
1M
DCM
VIN_SENSE
FB
EN/UVLO
95.3k
9.53k
LT8312
GATE
VREF
SENSE
INTVCC
OVP
GND
100k
221k
VC
20Ω
4.7µF
0.01Ω
2.2µF
8312 TA04
Related Parts
PART NUMBER DESCRIPTION
COMMENTS
LT3798
Off-Line Isolated No Opto Flyback Controller with Active PFC VIN and VOUT Limited Only By External Components
LT3752/
LT3752-1
Active Clamp Synchronous Forward Controllers with Internal Input Voltage Range: LT3752: 6.5V to 100V, LT3752-1: Limited Only By
Housekeeping Controller
Eternal Components
LT3753
Active Clamp Synchronous Forward Controller
Input Voltage Range: 8.5V to 100V
LT8311
Synchronous Rectifier Controller with Opto-Coupler Driver
for Forward Converters
Optimized for Use with Primary-Side LT3752/LT3752-1, LT3753 and
LT8310 Controllers
LT3748
100V Isolated Flyback Controller
5V ≤ VIN ≤ 100V, No Opto Flyback, MSOP-16 with High Voltage Spacing
LTC 3765/
LTC3766
Synchronous No Opto Forward Controller Chip Set with
Active Clamp Reset
Direct Flux Limit, Supports Self Starting Secondary Forward Control
LTC3723-1/
LTC3723-2
Synchronous Push-Pull and Full-Bridge Controllers
High Efficiency with On-Chip MOSFET Drivers, Adjustable Synchronous
Rectification Timing
LTC3722/
LTC3722-2
Synchronous Full Bridge Controllers
Adaptive or Manual Delay Control for Zero Voltage Switching, Adjustable
Synchronous Rectification Timing
®
14 Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
For more information www.linear.com/LT8312
(408) 432-1900 ● FAX: (408) 434-0507
●
www.linear.com/LT8312
8312fa
LT 0216 REV A • PRINTED IN USA
 LINEAR TECHNOLOGY CORPORATION 2015