ZXGD3101N8
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SYNCHRONOUS RECTIFIER CONTROLLER
Description
The ZXGD3101 is intended to drive MOSFETS configured as ideal
diode replacements. The device is comprised of a differential amplifier
detector stage and high current driver. The det ector monitors the
reverse voltage of the MOSFET such that if body diode conduction
occurs a positive voltage is applied to the MOSFET’s Gate pin.
Once the positive voltage is applied to the Gate the MOSFET
switches on allowing reverse current flow. The detectors’ output
voltage is then proportional to the MOSFET Drain-Source reverse
voltage drop and this is applied to the Gate via the driver. This action
provides a rapid turn off as current decays.
Application
• Flyback Converters in:
• Adaptors
• LCD Monitors
• Server PSU’s
• Set Top Boxes
• LLC Converter in:
• High Power Adaptors
• LCD TV
• Street Lighting
Refer to documents: AN54, AN69, DN90, DN91 and DN94 available
from the website
Features
• Turn-off propagation delay 15ns and turn-off time 20ns.
• Suitable for Discontinuous Mode (DCM), Critical
Conduction Mode (CrCM) and Continuous Mode (CCM)
operation
• Compliant with Energy Star V2.0 and European Code of
Conduct V3
• Halogen Free part
• 5-15V Vcc range
Mechanical Data
• Case: SO-8
• Marking Information: See Page 13
Ordering Information
Product Status Package Marking Reel size (inches) Tape width (mm) Quantity per reel
ZXGD3101N8TC Active SO-8 ZXGD3101 13 12 2500
ZXGD3101N8
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SYNCHRONOUS RECTIFIER CONTROLLER
Maximum Ratings
Parameter Symbol Limit Unit
Supply voltage (Note 1) VCC 15 V
Continuous Drain pin voltage (Note 1) VD -3 to180 V
GATEH and GATEL output Voltage (Note 1) VG -3 to VCC + 3 V
Driver peak source current ISOURCE 4 A
Driver peak sink current ISINK 7 A
Reference current IREF 25 mA
Bias voltage VBIAS VCC V
Bias current IBIAS 100 mA
Power dissipation at TA =25°C PD 490 mW
Operating junction temperature TJ -40 to +150 °C
Storage temperature TSTG -50 to +150 °C
Thermal Characteristics
Parameter Symbol Value Unit
Junction to ambient (Note 2) RJA 255 °C/W
Junction to lead (Note 3) RlA 120 °C/W
ESD Rating
Model Rating Unit
Human Body 4000 V
Machine 400 V
Notes: 1.All voltages are relative to GND pin
2. Mounted on minimum 1oz weight copper on FR4 PCB in still air conditions.
3. Output Drivers - Junction to solder point at end of the lead 5 and 6
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SYNCHRONOUS RECTIFIER CONTROLLER
Electrical Characteristics @TA = 25°C, VCC= 10V, RBIAS=1.8k, RREF=3k
Parameter Symbol Conditions Min. Typ. Max. Unit
Input and supply characteristics
Operating current IOP VDRAIN -200m V - 3 -
mA
VDRAIN 0V - 8 -
Gate Driver
Turn-off Threshold Voltage(Note 4)
VT V
G = 1V, (Note 5) -45 -16 0 mV
GATE output voltage (Note 4)
VG(off)
VDRAIN 0V, (Note 5) - 0.6 1
V
VG
VDRAIN = -60mV, (Note 6) 5.0 7.5 -
VDRAIN = -80mV, (Note 6) 7.0 8.5 -
VDRAIN = -100mV, (Note 6) 8.4 9 -
VDRAIN -140mV, (Note 6) 9.2 9.4 -
VDRAIN -200mV, (Note 6) 9.3 9.5 -
GATEH peak source current ISOURCE V
GH = 1V 2.5 - A
GATEL peak sink current ISINK V
GL = 5V 2.5 - A
Turn on Propagation delay td1
CL = 2.2nF, (Notes 6 and 7)
525 ns
Turn off Propagation delay td2 15 ns
Gate rise time tr 305 ns
Gate fall time tf 20 ns
Notes: 4. GATEH connected to GATEL
5. RH = 100k, RL = O/C
6. RL = 100k, RH = O/C
7. Refer to Fig 6: test circuit and Fig 7: timing diagram on Page 12
ZXGD3101N8
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SYNCHRONOUS RECTIFIER CONTROLLER
Schematic Symbol and Pin Out Details
Differential
amplifier
High volt
comparator
Threshold
voltage
control
Driver
Gate drive
amplitude
control
Turn-on/off
control
+
+
-
-
GATEH
GATEL
Vcc
GND
DRAIN
REF BIAS
Pin No. Symbol Description and function
1 NC No connection
This pin can be connected to GND
2 REF Reference
This pin is connected to VCC via resistor, RREF. RREF should be selected to source approximately 3mA into this pin.
(Note 8)
3 G ATEL Gate turn off
This pin sinks current, ISINK, from the synchronous MOSFET Gate.
4 GATEH Gate turn on
This pin sources current, ISOURCE, to the synchronous MOSFET Gate.
5 VCC Power Supply
This is the supply pin. It is recommended to decouple this point to ground closely with a ceramic capacitor.
6 GND Ground
This is the ground reference point. Connect to the synchronous MOSFET Source terminal.
7 BIAS Bias
This pin is connected to VCC via resistor, RBIAS. RBIAS should be selected to source 1.6 times IREF into this pin.
(Note 9)
8 DRAIN Drain connection
This pin connects directly to the synchronous MOSFET Drain terminal.
Notes: 8. REF pin should be assumed to be at GND +0.7V.
9. BIAS pin should be assumed to be at GND +0.3V.
ZXGD3101N8
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Operation
Normal Operation
The operation of the device is described step-by-step with reference to the timing diagram below.
1. The detector monitors the MOSFET Drain-Source voltage.
2. When, due to transformer action, the MOSFET body diode is forced to conduct there is approximately -0.6V on the Drain pin.
3. The detector outputs a positive voltage with respect to ground, this voltage is then fed to the M OSFET driver stage a nd current is sourced out o f
the GATEH pin.
4. The current out of the GATEH pin is sourced into the synchronous MOSFET Gate to turn the device on.
5. The GATEH output voltage is now proportional to the Drain-Source voltage drop across the MOSFET due to the current flowing through the
MOSFET.
6. MOSFET conduction continues until the drain current reaches zero.
7. At zero current the detector output voltage is zero and the s ynchronous MOSFET Gate voltage is pulled low by the GATEL, turning the device
off.
Drain
current
zero
Body Diode
Conduction
MOSFET
Gate Current
ZXGD3101N8
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SYNCHRONOUS RECTIFIER CONTROLLER
1a) Continuous Conducti on Mode (CCM)
1b) Critical Conduction Mode (CrCM)
1c) Discontinuous Conduction Mode (DCM)
Figure 1: Typical waveforms
ZXGD3101N8
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SYNCHRONOUS RECTIFIER CONTROLLER
Typical Characteristics
-400 -200 0 200 400 600 800 1000
-2
0
2
4
6
8
10
-20 0 20 40 60
-2
0
2
4
6
8
10
-50 -25 0 25 50 75 100 125 150
10
100
1000
-50 -25 0 25 50 75 100 125 150
8.0
8.1
8.2
8.3
8.4
8.5
8.6
0246810
0
5
10
15
20
25
30
35
1000 10000 100000
0
2
4
6
8
10
12
14
16
18
20
VD
Switc h On S p e e d
Vol tage (V)
Time (ns)
VG
See Fig.4
See Fig . 4
VG
VD
Switch Off Speed
Voltage (V)
Time (ns)
VCC=10V
RBIAS=1.8kΩ
RREF=3kΩ
CLOAD=2.2nF
RLOAD=1kΩ
ton
toff
Switching vs Temperature
Time (ns)
Temperature (°C)
Supply Current vs Temperature
F=100kHz
VCC=10V
RBIAS=1.8KΩ
RREF=3kΩ
CLOAD=2.2nF
RLOAD=100kΩ
Suppl y Curre nt (m A)
Temperature (°C)
F=100kHz, RBIAS=1.8kΩ
RREF=3kΩ, RLOAD=100kΩ
Supply Current vs Capacitive Load
Supply Current (mA)
Capacitance (n F)
Vcc=15V
Vcc=12V
Vcc=10V
Vcc= 8V
CLOAD=10nF
CLOAD=4.7nF
CLOAD=2.2nF
CLOAD=1nF
VCC=10V
RBIAS=1.8kΩ
RREF=3kΩ
RLOAD=100kΩ
Supp ly Cu rren t v s Frequ ency
Frequ ency (Hz)
Supply Current (mA)
ZXGD3101N8
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SYNCHRONOUS RECTIFIER CONTROLLER
-0.10 -0.08 -0.06 -0.04 -0.02 0.00
0
2
4
6
8
10
-0.10 -0.08 -0.06 -0.04 -0.02 0.00
0
2
4
6
8
10
Transfer Characteristic
VG Gate Voltage (V)
VD Drain Voltage (V)
IREF= 2mA
IREF=2.5mA
IREF= 3mA
IREF=3.5mA
IREF= 4mA
VCC = 10V
IBIAS= 5mA
RLOAD=1kΩ
IBIAS= 6mA
IBIAS=5.5mA
IBIAS= 5mA
IBIAS=4.5mA
IBIAS= 4mA
Transfer Ch aracteristic
VG Gat e Voltage (V)
VD Drain Vol tage (V)
VCC= 10V
IREF= 3mA
RLOAD=1kΩ
Component Selection
It is advisable to decouple the ZXGD3101 closely to VCC and ground due to the possibility of high peak gate currents with C1 in Figure 2.
The proper selection of external resistors RREF and RBIAS is important to the optimum device operation. Select a value for resistor RREF to give a
reference current, IREF, of ~3mA. The value of RBIAS must then be 0.6 times the value of RREF giving a bias current, IBIAS, of ~1.6 times IREF. This
provides a recommended typical offset voltage of ~20mV.
External gate resistors are optional. They can be inserted to control the rise times which may help with EMI issues, power supply consumption
issues or dissipation within the part.
RREF = (VCC -0.7V) / 0.003
RBIAS = (VCC -0.3V) / 0.005
Layout considerations
The Gate pins should be as close to the MOSFET Gate as possible. Also the ground return loop should be as short as possible. The decoupling
capacitor should be close to the VCC and Ground pin, and should be a X7R type.
For more detailed information refer to application note AN54..
ZXGD3101N8
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SYNCHRONOUS RECTIFIER CONTROLLER
Figure 2 Example connection for low side synchronous rectification
Figure 3: Example connection for hi gh side synchronous rectification
ZXGD3101N8
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SYNCHRONOUS RECTIFIER CONTROLLER
Package Outline and Dimensions
Suggested Pad Layout
Marking Information
Date Code Key
Year 2009 2010 2011 2012 2013 2014 2015
Code W X Y Z A B C
Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Code 1 2 3 4 5 6 7 8 9 O N D
SO-8
Dim Min Max
A - 1.75
A1 0.10 0.20
A2 1.30 1.50
A3 0.15 0.25
b 0.3 0.5
D 4.85 4.95
E 5.90 6.10
E1 3.85 3.95
e 1.27 Typ
h - 0.35
L 0.62 0.82
θ 0° 8°
All Dimensions in mm
Dimensions Value (in mm)
X 0.60
Y 1.55
C1 5.4
C2 1.27
Gauge Plan e
Seating Plane
Det ail ‘A’
Det ail ‘A’
E
E1
h
L
D
eb
A2
A1
A
45
°
7
°~
9
°
A3
0.254
X
C1
C2
Y
ZXGD
YM
3101
ZXGD3101 = Product Type Marking Code
YM = Date Code Marking
Y = Year (ex. W = 2009)
M = Month (ex. 9 = September)
ZXGD3101N8
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SYNCHRONOUS RECTIFIER CONTROLLER
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