DIODES ZXGD3103N8TC

A Product Line of
Diodes Incorporated
ZXGD3103N8
SYNCHRONOUS MOSFET CONTROLLER
Description
The ZXGD3103 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
detector 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.
Features
Applications
•
Proportional Gate Drive
•
Flyback Converters in:
•
Turn-off propagation delay 15ns and turn-off
time 20ns.
•
Adaptors
•
•
LCD Monitors
Detector threshold voltage ~10mV
•
•
Server PSU’s
Standby current 5mA
•
•
Set Top Boxes
Suitable for Discontinuous Mode (DCM),
Critical Conduction Mode (CrCM) and
Continuous Mode (CCM) operation
•
LCD TV
•
Resonant Converters
•
LED TV
•
High power Adaptors
•
Street Lighting
•
ATX psu
•
5-15V VCC range
Pin out details
Typical Configuration
SO-8
Ordering information
Device
Status
ZXGD3103N8TC Production
Package
Part Mark
Reel size
(inches)
Tape width
(mm)
Quantity per reel
SO8
ZXGD3103
13
12
2500
ZXGD
3103
YY WW
ZXGD
3103
YY
WW
Marking information
ZXGD3103N8
Document number: DS32255 Rev. 2 - 2
= Product Type Marking Code, Line 1
= Product Type Marking Code, Line 2
= Year (ex: 11 = 2011)
= Week (01 - 53)
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ZXGD3103N8
Absolute maximum ratings
Parameter
Symbol
Limit
Unit
Supply voltage1
VCC
15
V
Continuous Drain pin voltage1
VD
-3 to180
V
GATEH and GATEL output Voltage1
VG
-3 to VCC + 3
V
ISOURCE
2.5
A
Driver peak sink current
ISINK
6
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
Tstg
-50 to +150
°C
Symbol
Value
Unit
Junction to ambient (a)
RθJA
255
°C/W
Junction to lead (b)
RθlA
120
°C/W
Driver peak source current
Storage temperature
Notes:
1. All voltages are relative to GND pin.
Thermal resistance
Parameter
Notes:
a. Mounted on minimum 1oz weight copper on FR4 PCB in still air conditions.
b. Output Drivers - Junction to solder point at end of the lead 5 and 6
ESD Rating
Model
Rating
Unit
Human Body
2000
V
Machine
300
V
ZXGD3103N8
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Electrical characteristics at TA = 25°C; VCC = 10V; RBIAS = 3.3kΩ; RREF= 4.3kΩ
Parameter
Symbol
Conditions
Min.
Typ.
Max.
Unit
Input and supply characteristics
Operating current
IOP
VD ≤ -200m V
-
2.16
-
VD ≥ 0V
-
5.16
-
mA
Gate Driver
Turn-off Threshold
Voltage(**)
VT
VG = 1V, (*)
-16
-10
0
VG(off)
VD ≥ 0V, (*)
-
0.73
1
VD = -50mV, (g)
6.0
7.2
-
VD = -100mV, (g)
8.8
9.2
-
VD ≤ -150mV, (g)
9.2
9.4
-
VD ≤ -200mV, (g)
9.3
9.5
-
GATE output voltage (**)
VG
mV
V
Switching performance (“) for QG(tot) = 82nC
Turn on Propagation delay
150
td1
Turn off Propagation delay
td2
Gate rise time
tr
Gate fall time
tf
Refer to switching waveforms
in Fig. 3
15
450
Continuous Conduction Mode
21
Discontinuous Conduction
Mode
17
ns
Notes:
(**) GATEH connected to GATEL
(*) RH = 100kΩ, RL = O/C
(g) RL = 100kΩ, RH = O/C
(“) refer to test circuit below
ZXGD3103N8
Document number: DS32255 Rev. 2 - 2
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ZXGD3103N8
Schematic Symbol and Pin Out Details
Pin No.
Name
Description and function
1
NC
No Internal connection
2
REF
3
GATEL
4
GATEH
5
VCC
6
GND
7
BIAS
8
DRAIN
Reference
This pin is connected to VCC via resistor, RREF
Gate turn off
This pin sinks current, ISINK, from the synchronous MOSFET Gate.
Gate turn on
This pin sources current, ISOURCE, to the synchronous MOSFET Gate.
Power Supply
This is the supply pin. It is recommended to decouple this point to ground closely
with a ceramic capacitor.
Ground
This is the ground reference point. Connect to the synchronous MOSFET Source
terminal.
Bias
This pin is connected to VCC via resistor, RBIAS.
Drain connection
This pin connects directly to the synchronous MOSFET Drain terminal.
ZXGD3103N8
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Typical Characteristics
10
VCC = 15V
12
VCC = 12V
10
VCC = 10V
VCC = 5V
8
6
4
2
VG Gate Voltage (V)
VG Gate Voltage (V)
14
8
T
T
T
T
6
4
VCC = 10V
RBIAS=3K3
2
RREF=4K3
100k pull down
See Resistor Table for Values
0
-100
-80
-60
-40
-20
0
-100
0
VD Drain Voltage (mV)
-60
-40
-20
0
Transfer Characteristic
5
100
VCC = 10V
0
RBIAS=3K3
RREF=4K3
-5
VG = 1V
-10
100k pull up
-15
-20
-25
-50
-25
0
25
50
75
Supply Current (mA)
VD Drain Voltage (mV)
-80
VD Drain Voltage (mV)
Transfer Characteristic
VCC = 10V
RBIAS=3k3
RREF=4K3
D = 0.5
CLOAD=22nF
CLOAD=10nF
CLOAD=4.7nF
CLOAD=2.2nF
CLOAD=1nF
10
100 125 150
1k
10k
Temperature (°C)
100k
Frequency (Hz)
Drain Sense Voltage vs Temperature
Supply Current vs Frequency
1
100
RBIAS=3k3
80
RREF=4K3
60
D = 0.5
f=250kHz
0
VCC = 15V
VCC = 12V
40
VCC = 10V
20
VCC = 5V
Peak Current (A)
Supply Current (mA)
= -40°C
= 25°C
= 85°C
= 125°C
Current flow Supply to Gate
-1
VCC = 10V
-2
RBIAS=3K3
-3
RREF=4K3
T = 25°C
-4
-5
Current flow Gate to Ground
0
0
2
4
6
8
10 12 14 16 18 20 22
Capacitance (nF)
Document number: DS32255 Rev. 2 - 2
5
10
15
20
25
Capacitance (nF)
Supply Current vs Capacitive Load
ZXGD3103N8
0
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Gate Current vs Capacitive Load
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ZXGD3103N8
10
10
8
8
RBIAS=10k
6
CLOAD=10nF
Voltage (V)
Voltage (V)
Typical Characteristics
VCC=10V
6
RBIAS=3k3
VG
4
RREF=4K3
VD
CLOAD=10nF
2
VCC=10V
RREF=4K7
4
2
0
VD
VG
0
-2
-0.5
0.0
0.5
1.0
-2
1.5
-40 -20
0
Time (μs)
Time (ns)
Switch On Speed
Switch Off Speed
2
VCC=10V
Gate Current (A)
Gate Current (A)
0.3
RBIAS=3k3
RREF=4K3
0.2
CLOAD=10nF
0.1
0.0
-0.5
0.0
0.5
1.0
1
0
-1
-2
VCC=10V
-3
RREF=4K3
-4
CLOAD=10nF
1.5
Time (μs)
Percent Change Time (%)
VCC=10V
RBIAS=3k3
-40 -20
0
20 40 60 80 100 120 140
Time (ns)
Gate Drive On Current
6
20 40 60 80 100 120 140
Gate Drive Off Current
tON= tD + tR
RBIAS=3k3
RREF=4K3
4
CLOAD=10nF
2
tOFF= tD + tF
0
-2
-50
-25
0
25
50
75
100 125 150
Temperature (°C)
Switching vs Temperature
ZXGD3103N8
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Application information
The purpose of the ZXGD3103 is to drive a MOSFET as a low-VF Schottky diode replacement in offline
power converters. When combined with a low RDS(ON) MOSFET, it can yield significant power efficiency
improvement, whilst maintaining design simplicity and incurring minimal component count. Figure 1 and 2
show typical configuration of ZXGD3103 for synchronous rectification in a Flyback and a multiple output
resonant converter.
Figure 1. Example connections in Flyback supply
Figure 2. Example connections in LLC supply
ZXGD3103N8
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Descriptions of the normal operation
The operation of the device is described step-by-step with reference to the timing diagram in Figure 3.
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 0.8V on the Drain pin.
3. The detector outputs a positive voltage with respect to ground, this voltage is then fed to the MOSFET
driver stage and current is sourced out of the GATE pin.
4. The controller goes into proportional gate drive control — the GATE output voltage is proportional to the
on-resistance-induced Drain-Source voltage drop across the MOSFET. Proportional gate drive ensures that
MOSFET conducts for majority of the conduction cycle and minimizes body diode conduction time.
5. As the Drain current decays linearly toward zero, proportional gate drive control reduces the Gate voltage
so the MOSFET can be turned off rapidly at zero current crossing. The GATE voltage is removed when the
Drain-Source voltage crosses the detection threshold voltage to minimize reverse current flow.
6. At zero Drain current, the controller GATE output voltage is pulled low to VG(off) to ensure that the
MOSFET is off.
Figure 4 shows typical operating waveforms for ZXGD3103 driving a MOSFET with Qg(TOT) = 82nC in a
Flyback converter operating in critical conduction mode.
Figure 3. Timing diagram for a critical conduction mode Flyback converter
ZXGD3103N8
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Typical waveforms
Fig 4a: Critical conduction mode
Voltage (V)
Switch On Speed
10
9
8
7
6
VD
5
VG
4
3
2
1
0
-1
-2
-0.4 -0.2 0.0 0.2 0.4 0.6 0.8
VCC = 10V
RBIAS = 3K3
RREF = 4K3
Qg(TOT) = 82nC
1.0 1.2 1.4 1.6
Time (μs)
Fig 4b: Typical switch ON speed when driving a Qg(TOT) = 82nC MOSFET
Switch OFF Speed
10
9
8
Voltage (V)
7
VD
VCC = 10V
6
RBIAS = 3K3
5
RREF = 4K3
4
Qg(TOT) = 82nC
3
VG
2
1
0
-1
-2
-0.05 -0.04 -0.03 -0.02 -0.01 0.00 0.01 0.02 0.03 0.04 0.05
Time (μs)
Fig 4c: Typical switch OFF speed when driving a Qg(TOT) = 82nC MOSFET
ZXGD3103N8
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Design considerations
It is advisable to decouple the ZXGD3103 closely to VCC and ground due to the possibility of high peak gate
currents with a 1μF X7R type ceramic capacitor as shown in Figure 2. The Gate pins should be as close to
the MOSFET’s gate as possible. Also the ground return loop should be as short as possible.
To minimize parasitic inductance-induced premature turn-off issue of the synchronous controller always
keep the PCB track length between ZXGD3101’s Drain input and MOSFET’s Drain to less than 10mm. Low
internal inductance MOSFET packages such as SO-8 and PolarPak are also recommended for high
switching frequency power conversion to minimize body diode conduction.
R1, Q1 D1 and C1 in Figure 1 are only required as a series drop-down regulator to maintain a stable Vcc
around 10V from a power supply output voltage greater than 15V.
External gate resistors are optional. They can be inserted to control the rise and fall time which may help
with EMI issues.
The proper selection of external resistors RREF and RBIAS is important to the optimum device operation.
Select a value for resistor RREF and RBIAS from Table 1 based on the desired Vcc value. This provides the
typical ZXGD3103’s detection threshold voltage of 10mV.
Table 1. Recommended resistor values for various supply voltages
VCC
5V
10V
12V
15V
ZXGD3103N8
Document number: DS32255 Rev. 2 - 2
RBIAS
1K6
3K3
3K9
5K1
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RREF
2K0
4K3
5K1
6K8
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ZXGD3103N8
Package Outline and Dimensions
ZXGD3103N8
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without the express written approval of the Chief Executive Officer of Diodes Incorporated. As used herein:
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