APR343

A Product Line of
Diodes Incorporated
APR343
SECONDARY SIDE SYNCHRONOUS RECTIFICATION CONTROLLER
Description
Pin Assignments
NEW PRODUCT
APR343 is a secondary side MOSFET driver for synchronous
rectification in DCM operation, which integrates the output voltage
detection function for primary side control system.
(Top View)
The synchronous rectification can effectively reduce the secondary
side rectifier power dissipation and provide high performance solution.
By sensing MOSFET drain-to-source voltage, APR343 can output
ideal drive signal with less external components. It can provide high
performance solution for 5V output voltage application.
Same as AP4341, APR343 detects the output voltage and provides a
periodical signal when the output voltage is lower than a certain
threshold. By fast response to secondary side voltage, APR343 can
effectively improve the transient performance of primary side control
system.
DRISR
1
GND
2
VCC
3
5
VDET
4
AREF
SOT25
The APR343 is available in SOT25 package.
Applications
Features







Synchronous Rectification for DCM Operation Flyback
Eliminate Resonant Ring Interference
Fast Detector of Supply Voltage
Fewest External Components
Totally Lead-free & Fully RoHS Compliant (Notes 1 & 2)
Halogen and Antimony Free. “Green” Device (Note 3)
Notes:

Adapters/Chargers for Cell/Cordless Phones, ADSL Modems,
MP3 and Other Portable Apparatus
Standby and Auxiliary Power Supplies
1. No purposely added lead. Fully EU Directive 2002/95/EC (RoHS) & 2011/65/EU (RoHS 2) compliant.
2. See http://www.diodes.com/quality/lead_free.html for more information about Diodes Incorporated’s definitions of Halogen- and Antimony-free, "Green"
and Lead-free.
3. Halogen- and Antimony-free "Green” products are defined as those which contain <900ppm bromine, <900ppm chlorine (<1500ppm total Br + Cl) and
<1000ppm antimony compounds.
Typical Applications Circuit
T1
C20
+
Q2
C22
R21
5
1
VDET
DRISR
3
APR343
AREF
GND
4
2
R22
VCC
C21
R20
APR343
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APR343
NEW PRODUCT
Pin Descriptions
Pin Number
Pin Name
Function
1
DRISR
2
GND
Ground
3
VCC
Power supply, connected with system output
4
AREF
Program a voltage reference with a resistor from AREF to GND, to enable synchronous rectification
MOSFET drive signal
5
VDET
Synchronous rectification sense input and dynamic function output, connected with secondary winding
Synchronous rectification MOSFET Gate drive
Functional Block Diagram
VCC
3
VREF
VDET
Integrator
( VDET -VCC )* tONP
IOVP
Dynamic
OVP
IAREF
Counter
tONPDET
AREF
DRISR
4
1
OSC
SRDRIVER
2
GND
5
VDET
APR343
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APR343
Absolute Maximum Ratings (Note 4)
Symbol
Rating
Unit
-0.3 to 7.5
V
VCC
Supply Voltage
VDET
Voltage at VDET Pin
-2 to 50
V
Voltage at AREF, DRISR Pin
-0.3 to 6
V
Internally limited
A
VAREF, VDRISR
–
NEW PRODUCT
Parameter
Output Current at VDET
PD
Power Dissipation at TA = +25ºC
0.6
W
TJ
Operating Junction Temperature
+150
ºC
-65 to +150
ºC
Lead Temperature (Soldering, 10 sec)
+300
ºC
θJA
Thermal Resistance (Junction to Ambient)
197
ºC/W
θJC
Thermal Resistance (Junction to Case)
76
ºC/W
TSTG
–
Storage Temperature
Note 4: Stresses greater than those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and
functional operation of the device at these or any other conditions beyond those indicated under “Recommended Operating Conditions” is not implied.
Exposure to “Absolute Maximum Ratings” for extended periods may affect device reliability.
Recommended Operating Conditions
Symbol
VCC
TA
Parameter
Supply Voltage
Ambient Temperature
APR343
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Min
Max
Unit
0
6
V
-40
+85
ºC
December 2014
© Diodes Incorporated
A Product Line of
Diodes Incorporated
APR343
Electrical Characteristics
Symbol
(@VCC = 5V, TA = +25C, unless otherwise specified.)
Parameters
Conditions
Min
Typ
Max
Unit
Supply Voltage ( VCC Pin )
ISTARTUP
NEW PRODUCT
IOP
VSTARTUP
–
Startup Current
VCC = VSTARTUP-0.1V
–
100
150
µA
Operating Current
VDET pin floating
VCC = VTRIGGER+20mV
40
100
150
µA
Startup Voltage
–
2.6
3.1
3.4
V
UVLO
–
2.3
2.8
3.1
V
Internal Trigger Voltage
–
5.25
5.3
5.35
V
Duty Cycle
–
4
8
12
%
Oscillation Period
VCC = 5V
18
30
37.5
µs
Dynamic Output Section/Oscillator Section
VTRIGGER
–
tOSC
VCC = VTRIGGER, VCC/VDET pin
Internal Trigger Current
is separately connected to a 20Ω
resistor
30
–
42
mA
tDIS
Minimum Period
–
18
30
37.5
ms
VDIS
Discharge Voltage
–
5.28
5.44
5.52
V
IDIS
Discharge Current
VCC = VDIS+0.1V
1.5
3
4.5
mA
Trigger Discharger Gap
–
30
110
–
mV
VOVP
Overshoot Voltage for Discharge
–
5.8
5.9
6.0
V
IOVP
Overshoot Current for Discharge
40
–
100
mA
ITRIGGER
VDIS-VTRIGGER
VCC = VOVP+0.1V, VCC pin is
connected to a 20Ω resistor
Synchronous Rectification Detection and Drive
VTHON
Gate Turn On Threshold
–
0
–
1
V
VTHOFF
Gate Turn Off Threshold
–
-20
-12.5
-5
mV
tDON
Turn On Delay Time
From VTHON to VDRISR = 1V
–
70
130
ns
tDOFF
Turn Off Propagation Delay Time
From VTHOFF to VDRISR = 3V
–
100
150
ns
tRG
Turn On Rising Time
From 1V to 3V, CL = 4.7nF
–
50
100
ns
tFG
Turn Off Falling Time
From 3V to 1V, CL = 4.7nF
–
50
100
ns
(VDET-VCC)*tONP = 25Vµs
0.9
1.8
2.7
(VDET-VCC)*tONP = 50Vµs
–
–
6.5
3.7
–
–
V
tLEB_S
Minimum On Time
tLEB_L
VDRISR_HIGH
VS_MIN
tOVP_LAST
Kqs
Notes:
µs
Drive Output Voltage
VCC = 5V
Synchronous Rectification (SR)
Minimum Operating Voltage (Note 5)
–
–
–
4.5
V
Added OVP Discharge Time
–
–
2.0
–
ms
(Note 6)
(VDET-VCC)*tONP = 25Vµs
0.325
–
0.625
mA*µs
5. This item specifies the minimum SR operating voltage of VIN_DC, VIN_DC≥NPS*VS_MIN.
6. This item is used to specify the value of RAREF.
APR343
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A Product Line of
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APR343
Performance Characteristics
3.50
3.5
3.25
3.0
3.00
2.5
UVLO (V)
Startup Voltage (V)
UVLO vs. Temperature
2.75
2.0
2.50
1.5
2.25
2.00
-40
-20
0
20
40
60
80
100
120
1.0
-40
140
-20
0
20
60
80
100
120
140
o
Temperature ( C)
Internal Trigger Voltage vs. Temperature
Internal Trigger Current vs. Temperature
80
5.4
70
Internal Trigger Current (mA)
5.3
Internal Trigger Voltage (V)
40
Temperature ( C)
o
5.2
5.1
5.0
4.9
4.8
60
50
40
30
20
10
4.7
-40
-20
0
20
40
60
80
100
120
0
-40
140
-20
0
20
40
60
80
100
120
140
o
Temperature ( C)
o
Temperature ( C)
Overshoot Voltage for Discharge vs. Temperature
Overshoot Current for Discharge vs. Temperature
160
Overshoot Current for Discharge (mA)
6.0
Overshoot Voltage for Discharge (V)
NEW PRODUCT
Startup Voltage vs. Temperature
5.8
5.6
5.4
5.2
140
120
100
80
60
40
20
5.0
-40
-20
0
20
40
60
80
100
120
0
-40
140
Document number: DS36884 Rev. 4 - 2
0
20
40
60
80
100
120
140
Temperature ( C)
Temperature ( C)
APR343
-20
o
o
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APR343
Performance Characteristics (Cont.)
Gate Turn Off Threshold vs. Temperature
Kqs (See Note 6) vs. Temperature
0.7
0
0.5
Kqs (mA*s)
Gate Turn Off Threshold (mV)
-10
-20
0.4
0.3
0.2
-30
0.1
-40
-40
-20
0
20
40
60
80
100
120
0.0
-40
140
o
-20
0
20
40
60
80
100
120
140
o
Temperature ( C)
Temperature ( C)
Operating Current vs. Temperature
140
120
Operating Current (A)
NEW PRODUCT
0.6
100
80
60
40
20
0
-40
-20
0
20
40
60
80
100
120
140
o
Temperature ( C)
APR343
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APR343
Output Voltage Detection Function Description
tOSC
tDIS
tDIS
tDIS
tDIS
tDIS
tDIS
tOSC
VDET
VOVP
VDIS
VDIS
NEW PRODUCT
VTRIGGER
VCC
VTRIGGER
VON
UVLO
IOVP
IVCC
VOFF
tOVP_LAST
IDIS
Figure 1. Typical Waveforms 1 of APR343
When VCC is beyond power-on voltage (VON), the APR343 starts up. The VDET pin asserts a periodical pulse and the oscillation period is t OSC.
When VCC is beyond the trigger voltage (VTRIGGER), the periodical pulse at VDET pin is discontinued. When V CC is beyond the discharge voltage
(VDIS), the discharge circuit will be enabled, and a 3mA current (IDIS) will flow into VCC pin. When VCC is higher than the overshoot voltage (VOVP),
the APR343 will enable a discharge circuit, the discharge current (IOVP) will last tOVP_LAST time. After the tOVP_LAST time, APR343 will stop the
discharge current and detect VCC voltage again. If VCC is still higher than VOVP, the tOVP_LAST time discharge current will be enabled again. Once the
OVP discharge current is asserted, the periodical pulse at VDET pin will be disabled.
When the VCC is below the power-off voltage (VOFF), the APR343 will be shut down.
MOSFET Driver Operation Description
I,V
VDET
IS
VTHON
0
t
VTHOFF
VDRISR
0.9VDRISR
0.9VDRISR
0.1VDRISR
0
tDON
tRG
tDOFF
0.1VDRISR
t
tFG
Figure 2. Typical Waveforms 2 of APR343
APR343
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APR343
MOSFET Driver Operation Description (Cont.)
The operation of the SR is described with timing diagram shown in Figure 2. APR343 monitors the MOSFET drain-source voltage. When the drain
voltage is lower than the turn-on threshold voltage VTHON, the IC outputs a positive drive voltage after a turn-on delay time (tDON). The MOSFET will
turn on and the current will transfer from the body diode into the MOSFET’s channel.
NEW PRODUCT
In the process of drain current decreasing linearly toward zero, the drain-source voltage rises synchronically. When it rises over the turn off
threshold voltage VTHOFF, APR343 pulls the drive signal down after a turn off delay (t DOFF).
Minimum On Time
When the controlled MOSFET gate is turned on, some ringing noise is generated. The minimum on-time timer blanks the VTHOFF comparator,
keeping the controlled MOSFET on for at least the minimum on time. If VTHOFF falls below the threshold before minimum on time expires, the
MOSFET will keep on until the end of the minimum on time.
The minimum on time is in direct proportion to the (VDET-VCC)*tONP. When (VDET-VCC)*tONP=5V*5µs, the minimum on time is about 1.8µs.
The Value and Meaning of AREF Resistor
As to DCM operation Flyback converter, after secondary rectifier stops conduction the primary MOSFET Drain-to-source ringing waveform is
resulted from the resonant of primary inductance and equivalent switch device output capacitance. This ringing waveform probably leads to
Synchronous Rectifier error conduction. To avoid this fault happening, APR343 has a special function design by means of volt-second product
detecting. From the sensed voltage of VDET pin to see, the volt-second product of voltage above VCC at primary switch on time is much higher
than the volt-second product of each cycle ringing voltage above VCC. Therefore, before every time Synchronous Rectifier turning on, APR343
judges if the detected volt-second product of VDET voltage above VCC is higher than a threshold and then turn on synchronous Rectifier. The
purpose of AREF resistor is to determine the volt-second product threshold. APR343 has a parameter, Kqs, which converts R AREF value to voltsecond product.
Area2  R AREF * Kqs
In general, Area1 and Area3 value depend on system design and always are fixed after system design frozen. As to BCD PSR design, the Area1
value changes with primary peak current value and Area3 value generally keeps constant at all of conditions. So the AREF resistor design should
consider the worst case, the minimum primary peak current condition. Since of system design parameter distribution, Area1 and Area3 have
moderate tolerance. So Area2 should be designed between the middle of Area1 and Area3 to keep enough design margin.
Area3  R AREF * Kqs  Area1
Area1=(VDET-VCC)*tONP
Area3
VDET
VCC
Area2=Kqs*RAREF
Figure 3. AREF Function
SR Minimum Operating Voltage
APR343 sets a minimum SR operating voltage by comparing the difference between VDET and output voltage (VCC). The value of VDET–VCC must be
higher than its internal reference, then APR343 will begin to integrate the area of (VDET–VCC)*tONP. If not, the area integrating will not begin and the
SR driver will be disabled.
APR343
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APR343
Ordering Information
APR343 X XX – XX
NEW PRODUCT
Product Name
Package
Temperature Range
SOT25
-40C to +85C
Package
Packing
RoHS/Green
K : SOT25
TR : Tape & Reel
G1 : Green
Part Number
APR343KTR-G1
Marking ID
GHZ
Packing
3000/Tape & Reel
Marking Information
(Top View)
: Logo
GHZ: Marking ID
APR343
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APR343
Package Outline Dimensions (All dimensions in mm(inch).)
(1)
Package Type: SOT25
0.300(0.012)
0.600(0.024)
0.100(0.004)
0.200(0.008)
1.500(0.059)
1.700(0.067)
3.000(0.118)
2.650(0.104)
NEW PRODUCT
2.820(0.111)
3.100(0.122)
0.200(0.008)
0.700(0.028)
REF
0.300(0.012)
0.500(0.020)
0°
8°
1.800(0.071)
2.000(0.079)
0.000(0.000)
MAX
1.450(0.057)
0.950(0.037)
TYP
0.150(0.006)
0.900(0.035)
1.300(0.051)
APR343
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APR343
Suggested Pad Layout
Package Type: SOT25
NEW PRODUCT
(1)
E2
G
Z
E1
Y
X
Dimensions
Z
(mm)/(inch)
G
(mm)/(inch)
X
(mm)/(inch)
Y
(mm)/(inch)
E1
(mm)/(inch)
E2
(mm)/(inch)
Value
3.600/0.142
1.600/0.063
0.700/0.028
1.000/0.039
0.950/0.037
1.900/0.075
APR343
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APR343
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NEW PRODUCT
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