HT7A6312 Low Power Primary Switcher for Off Line SMPS

HT7A6312
Low Power Primary Switcher for Off Line SMPS
Features
Applications
• Fixed 60kHz switching frequency
• Off line power supply for battery charger adapters
• 9V to 38V wide range VCC voltage
• Standby power supply for TV or monitors
• Wide AC input range from 85VAC to 265VAC
• Auxiliary supply for motor control
• PWM with current mode control
• Air conditioner power supply
• Auxiliary Under Voltage Lock Out with hysteresis
• Electromagnetic oven power supply
• High voltage start-up current source
• Excellent standby low power consumption
General Description
• Over-temperature, Over-current and Over-voltage
protection with auto-restart
The HT7A6312 is highly functionally integrated
device which combines an integrated PWM controller
with current mode control and a high voltage power
MOSFET on the same silicon chip.
• Integrated 730V MOSFET
• Burst mode under low load conditions
Typical Power Capability
8SOP
8DIP
European (195~265VAC)
Type
8W
13W
US (85~265VAC)
5W
8W
Typical Performance Characteristics Application Circuit
Isolation Flyback Topology
Snubber Circuit
VOUT+
Vac
VOUT-
SW
VCC
HT7A6312
VSS
PC817
FB
TL 431
Rev. 1.00
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December 24, 2014
HT7A6312
Block Diagram
SW
VCC
Regulator
60kHz
Oscillator
On/Off
Internal Supply
OTP
Detector
UVLO
R1
S
R2
8V/14.5V
R
R3
Q
Q
PWM
Latch
R4
S
38V
Over Voltage
Latch
FB
0.23V
LEB
RFB2
RFB1
VSS
Pin Assignment
VSS
1
8
SW
VSS
1
8
SW
VSS
2
7
SW
VSS
2
7
SW
FB
3
6
SW
FB
3
6
SW
VCC
4
5
SW
VCC
4
5
SW
HT7A6312
8 DIP-A
HT7A6312
8 SOP-A
Pin Description
Pin No.
8SOP
8DIP
1, 2
1, 2
3
4
3
4
5, 6, 7, 8 5, 6, 7, 8
Rev. 1.00
Pin Name
VSS
Description
Power MOSFET source and circuit ground reference.
FB
Feedback input. The useful voltage range extends from 0V to 1V, and defines
the peak drain MOSFET current. The current limitation, which corresponds to the
maximum drain current, is obtained for when the FB pin is shorted to the SOURCE
pin.
VCC
Control circuits power supply. Also provides a charging current during start up
thanks to a high voltage current source connected to SW. For this purpose, a
hysteresis comparator monitors the VCC voltage and provides two thresholds:
VCCON: Voltage value (typically 14.5V) at which the device starts switching and turns
off the start up current source.
VCCOFF: Voltage value (typically 8V) at which the device stops switching and turns
on the start up current source.
SW
Power MOSFET drain. Also used by the internal high voltage current source during
the start up phase to charge the external VCC capacitor.
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HT7A6312
Absolute Maximum Ratings
Symbol
Parameter
VDS(sw)
Switching Drain Source Voltage (TJ=25 to 125°C)
VDS(st)
Start-up Drain Source Voltage (TJ=25 to 125°C)(2)
ID
Continuous Drain Current
VCC
Supply Voltage
IFB
Feedback Current
(1)
Unit
-0.3 to 730
V
-0.3 to 400
V
Internally limited
A
0 to 41
V
Electrostatic Discharge: Machine mode
VESD
Value
Electrostatic Discharge: Human body mode
3
mA
400
V
3
kV
TC
Operating Temperature Range
-40 to 150
°C
TSTG
Storage Temperature Range
-55 to 150
°C
TJ
Junction Operating Temperature
Internally limited
°C
Note: 1.This parameter applies when the start-up current source is off. This is the case when the VCC voltage has
reached VCCON and remains above VCCOFF.
2. This parameter applies when the start up current source is on. This is the case when the VCC voltage has
not yet reached VCCON or has fallen below VCCOFF.
Thermal Data
Symbol
Parameter
8SOP
8DIP
Unit
RTHJC
Thermal resistance junction-case
25
15
°C/W
RTHJA
Thermal resistance ambient-case(1)
55
45
°C/W
Note: When mounted on a standard single-sided FR4 board with 200mm2 of Cu (at least 35μm thick) connected to
all SW pins.
Rev. 1.00
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December 24, 2014
HT7A6312
Electrical Characteristics
Symbol
Ta=25°C, VCC=18V, unless otherwise specified
Parameter
Test Conditions
Min. Typ. Max. Unit
Power Section
BVDSS
Drain-Source Voltage
ID=1mA; VFB=2V
730
—
—
V
IDSS
Off State Drain Current
VDS=500V; VFB=2V; TJ=125°C
—
—
0.1
mA
rDS(ON)
Static Drain-Source On State Resistance
ID=0.2A
—
19
22
Ω
(1)
tF
Fall Time
ID=0.1A; VIN=300V
—
100
—
nS
tR
Rise Time
ID=0.2A; VIN=300V(1)
—
50
—
nS
COSS
Drain Capacitance
VDS=25V
—
20
—
pF
Supply Section
ICCCH
Start-Up Charging Current
VDS=100V; VCC=0V to VCCON
—
-1
—
mA
ICCOFF
Start-Up Charging Current In Thermal
Shutdown
VCC=5V; VDS=100V
TJ > TSD - THYST
0
—
—
mA
Operating Supply Current Not Switching
IFB=2mA
0.55 0.65
0.8
mA
Operating Supply Current Switching
IFB=0.5mA; ID=50mA(2)
0.5
0.7
0.9
mA
%
ICC
DRST
Restart Duty-Cycle
—
—
16
—
VCCOFF
VCC Under-voltage Shutdown Threshold
—
7
8
9
V
VCCON
VCC Start-Up Threshold
—
13
14.5
16
V
VCCHYST
VCC Threshold Hysteresis
—
5.8
6.5
7.2
V
VCCOVP
VCC Over-voltage Threshold
—
35
38
41
V
VCC=VCCOFF to 35V; TJ=0 to 100°C
54
60
66
kHz
—
Oscillation Section
Oscillator Frequency Total Variation
fOSC
PWM Comparator Section
GID
IFB to ID Current Gain
IDLIM
Peak Current Limitation
—
IFBSD
IFB Shutdown Current
RFB
FB Pin Input Impedance
ID=0mA
ID=0.2A
VFB=0V
—
—
320
—
0.32
0.4
0.48
A
—
0.9
—
mA
—
1.2
—
kΩ
nS
tD
Current Sense Delay to Turn-Off
—
200
—
tB
Blanking Time
—
—
350
—
nS
tONMIN
Minimum Turn-On Time
—
—
550
—
nS
Over-temperature Section
TSD
Thermal Shutdown Temperature
—
140
170
—
°C
THYST
Thermal Shutdown Hysteresis
—
—
40
—
°C
Note: Absolute maximum ratings indicate limits beyond which damage to the device may occur. Operating Ratings
indicate conditions for which the device is intended to be functional, but do not guarantee specific performance limits. The guaranteed specifications apply only for the test conditions listed.
1. For clamped inductive load
2. These test conditions are obtained with a resistive load which permit the maximum conduction time of
the device.
Rev. 1.00
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December 24, 2014
HT7A6312
Functional Description
Under Voltage Lock Out – UVLO
The HT7A6312 is highly functionally integrated
device which combines an integrated PWM controller
with current mode control and a high voltage power
MOSFET on the same silicon chip. The secondary
side feedback signal passes through a photo-coupler
on the primary side while the output voltage is
regulated by the device according to the feedback
signal. The device has a small quiescent current
and low power consumption when operating in
the standby mode. It also has a range of protection
features to protect the controller from fault conditions.
When the fault condition happens, the device will
shut down the power MOSFET and cause the VCC
voltage to fall. When the VCC voltage is lower than the
UVLO lower voltage (8V), the protection circuits will
be reset and the internal high voltage start up current
source will charge the VCC capacitor. Not until the VCC
voltage reaches the UVLO higher voltage (14.5V),
the device will resume normal operation. In this way,
the auto-restart function can enable and disable the
power MOSFET switching alternately until the fault
condition is eliminated.
High Voltage Start up
Thermal Shutdown – TSD
The SW pin in the device is a high voltage start up
current source. This current source will generate a
current which is regulated from a high voltage and
which will charge the VCC pin until the UVLO
is triggered when an AC voltage is applied on the
converter input. When the VCC voltage is larger than
the UVLO trigger voltage, the high voltage start up
current source will be cut off by UVLO and the device
will start operation by switching the power MOSFET
on and off.
Because the device integrates the controller and the
power MOSFET on the same chip, the temperature
of the device including the power MOSFET can be
easily detected. When the temperature is over 170°C,
the thermal shutdown protection function will be
active to turn off the power MOSFET. The device will
resume normal operation when the device temperature
is lower than the recovery temperature of about 130°C
and when the VCC voltage is lower than 2V.
Over Voltage Protection – OVP
Feedback
When a malfunction occurs in the secondary side
feedback circuit, or if a wiring defect allows the
feedback loop to be open, the current through the
opto-coupler will be near to zero. At this time, as
the excess energy will be supplied to the output,
the output voltage may be higher than the regulated
voltage and may damage the components in the
secondary side. The device includes an over voltage
protection function to avoid this condition happening.
If the V CC voltage is higher than 38V, the device
will be shut down by the OVP protection function to
prevent the malfunctions from damaging components.
The FB pin determines the device operation. The
power MOSFET current will be sensed by the
current sensing resistor which is connected between
the source terminal of the power MOSFET and the
ground terminal. In addition, this sensing resistor
also senses the current coming from the FB pin. The
voltage across the resistor will be compared to a fixed
reference voltage (0.23V). The power MOSFET is
turned off when the sensing resistor voltage is larger
than 0.23V.
Leading Edge Blanking – LEB
When the power MOSFET is turned on, there is
usually a high current spike which is generated by the
primary side capacitor and the secondary side rectifier
diode reverse recovery. This spike will be sensed by
the sensing resistor to indicate an excessive voltage
which will in turn lead to false feedback operation
in the current mode PWM control circuit. In order to
avoid this problem, the device includes a leading edge
blanking circuit which inhibits the comparator for a
short time after the power MOSFET is turned on.
Rev. 1.00
5
December 24, 2014
HT7A6312
Application Circuits
Buck Topology
EMI Solution
VCC
FB
HT7A6312
VSS
SW
VOUT+
Vac
VOUT-
Buck − Boost Topology
EMI Solution
VCC
FB
HT7A6312
SW
VSS
VOUT-
Vac
VOUT+
Non-Isolation Flyback Topology
Snubber Circuit
VOUT1
Vac
VOUT2
VCC
SW
HT7A6312
FB
VSS
Rev. 1.00
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December 24, 2014
HT7A6312
Package Information
Note that the package information provided here is for consultation purposes only. As this information may be
updated at regular intervals users are reminded to consult the Holtek website for the latest version of the package
information.
Additional supplementary information with regard to packaging is listed below. Click on the relevant section to be
transferred to the relevant website page.
• Further Package Information (include Outline Dimensions, Product Tape and Reel Specifications)
• Packing Meterials Information
• Carton information
Rev. 1.00
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December 24, 2014
HT7A6312
8-pin DIP (300mil) Outline Dimensions
Symbol
Min.
Nom.
Max.
A
0.355
0.365
0.400
B
0.240
0.250
0.280
C
0.115
0.130
0.195
D
0.115
0.130
0.150
E
0.014
0.018
0.022
F
0.045
0.060
0.070
G
—
0.100 BSC
—
H
0.300
0.310
0.325
I
—
—
0.430
Symbol
Rev. 1.00
Dimensions in inch
Dimensions in mm
Min.
Nom.
Max.
10.16
A
9.02
9.27
B
6.10
6.35
7.11
C
2.92
3.30
4.95
D
2.92
3.30
3.81
E
0.36
0.46
0.56
F
1.14
1.52
1.78
G
—
2.54 BSC
—
H
7.26
7.87
8.26
I
—
—
10.92
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December 24, 2014
HT7A6312
8-pin SOP (150mil) Outline Dimensions
Symbol
Dimensions in inch
Min.
Nom.
A
—
0.236 BSC
—
B
—
0.154 BSC
—
Max.
0.020
C
0.012
—
C′
—
0.193 BSC
—
D
—
—
0.069
E
—
0.050 BSC
—
F
0.004
—
0.010
G
0.016
—
0.050
H
0.004
—
0.010
α
0°
—
8°
Symbol
Rev. 1.00
Dimensions in mm
Min.
Nom.
Max.
A
—
6.00 BSC
—
B
—
3.90 BSC
—
C
0.31
—
0.51
C′
—
4.90 BSC
—
D
—
—
1.75
E
—
1.27 BSC
—
F
0.10
—
0.25
G
0.40
—
1.27
H
0.10
—
0.25
α
0°
—
8°
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December 24, 2014
HT7A6312
Copyright© 2014 by HOLTEK SEMICONDUCTOR INC.
The information appearing in this Data Sheet is believed to be accurate at the time
of publication. However, Holtek assumes no responsibility arising from the use of
the specifications described. The applications mentioned herein are used solely
for the purpose of illustration and Holtek makes no warranty or representation that
such applications will be suitable without further modification, nor recommends
the use of its products for application that may present a risk to human life due to
malfunction or otherwise. Holtek's products are not authorized for use as critical
components in life support devices or systems. Holtek reserves the right to alter
its products without prior notification. For the most up-to-date information, please
visit our web site at http://www.holtek.com.tw.
Rev. 1.00
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December 24, 2014