VISHAY SI4700DY

Si4700DY
New Product
Vishay Siliconix
Power Selector Switch
MOSFETs Configured To Give Spdt Switch
With One Control Input
2.5- to 8-V Ground Referenced Control Input
30-m Main Switch On-Resistance
70-m Alternate Switch On-Resistance
SOIC-8 Package
3000-V ESD Protection On Control Input
Zero Power Consumption In Alternate Power
Mode
ACPI Power Switching In Desktop
Computers
The Si4700DY consists of two MOSFETs configured for use as
a single-pole, double-throw (SPDT) switch. A single ground
referenced input, controls which switch is on. The Si4700DY
is intended for use in applications where two power sources
are available and the circuit must select one of the two
depending on the conditions. An example of such a circuit is
ACPI implementation in computers where part of a circuit must
switch to an “always-on” power supply when the computer is
in suspend mode, but runs off the main power supply for
normal operation.
4
Q1
5, 6, 7
VS2
VD
RG
8
VG
3
Q2
CO
1
Load
VS1
Q3
ON/OFF
2
GND
Document Number: 71110
S-00025—Rev. A, 24-Jan-00
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2-1
Si4700DY
New Product
Vishay Siliconix
ABSOLUTE MAXIMUM RATINGS (TA = 25_C UNLESS OTHERWISE NOTED)
Parameter
Symbol
Q1
Drain-Source Voltage
Q2
Logic Control Input
10 sec
Q1
Q2
Q1
Pulsed Drain Currentb
Q2
Q1
Continuous Intrinsic Diode Conductiona
Q2
Maximum Power Dissipationa
ID
–12
PD
Operating Junction and Storage Temperature Range
ESD Voltagec
V
8
7.6
5.3
5.0
3.5
20
IDM
IS
Unit
12
VDS
VIN
Continuous Drain Currenta
Steady State
A
20
2.1
1.15
2.1
1.15
2.35
1.25
W
Tj, Tstg
–55 to 150
_C
ESD
3
KV
Notes
a. Surface mounted on 1” x1” FR4 board.
b. Pulse test: pulse width 300 mS, duty cycle 2%.
c. Equivalent to MIL-STD-883D Human Body Model (100 pF, 1500 W)
THERMAL RESISTANCE RATINGS
Parameter
Symbol
t 10 sec
Maximum Junction-to-Ambienta
Steady State
Maximum Junction-to-Foot (Drain)b
Steady State
RthJA
RthJF
Typical
Maximum
43
53
82
100
25
30
Unit
_C/W
C/W
Notes
a. Surface Mounted on 1” x 1” FR4 Board.
b. Junction-to-foot thermal impedance represents the effective thermal impedance of all heat carrying leads in parallel and is intended for use in conjunction with
the thermal impedance of the PC board pads to ambient (RthJA = RthJF + RthPCB-A). It can also be used to estimate chip temperature if power dissipation and
the lead temperature of a heat carrying (drain) lead is known.
SPECIFICATIONS
Limits
Parameter
P
Symbol
S b l
VDS = –12 V, VGS = 0 V
Off S
State Leakage
L k
Current
C
Gate-Body Leakage
Gate-Threshold Voltage
O R i
On-Resistance
IDSS
Min
Specific
Test Conditions
S
ifi T
C di i
Typa
Max
Q1
1
Q2
–1
VDS = –8 V, VGS = 0 V
Q3
1
VDS = –12 V, VGS = 0 V, TJ = 55_C
Q2
–5
IGSS
VDS = 0 V, VGS = 4.5 V
Q3
VGS(th)
VDS = VGS, ID = 250 mA
Q3
VS = 4.5 V, ID = 1 A, VON/OFF = 2.5 V
Q1
25
30
VS = 2.5 V, ID = 1 A, VON/OFF = 2.5 V
Q1
32
40
VS = 4.5 V, ID = 1 A, VON/OFF = 2.5 V
Q2
58
70
VS = 2.5 V, ID = 1 A, VON/OFF = 2.5 V
Q2
90
110
rDS(on)
Unit
mA
A
1
0.6
V
mW
W
Notes
a. Typical values are for DESIGN AID ONLY, not guaranteed nor subject to production testing.
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Document Number: 71110
S-00025—Rev. A, 24-Jan-00
Si4700DY
New Product
Vishay Siliconix
PIN CONFIGURATION
SO-8
VIN
1
8
VGATE
GND
2
7
DRAIN
Q2 SOURCE
3
6
DRAIN
Q1 SOURCE
4
5
DRAIN
TRUTH TABLE
VIN
Q1
Q2
L
ON
OFF
H
OFF
ON
Top View
Order Number: Si4700DY
PIN DESCRIPTION
Pin Number
Symbol
Description
1
VON/OFF
2
GND
3
Q2 SOURCE
Input for alternate power
4
Q1 SOURCE
Input for main power
5, 6, 7
DRAIN
Output
8
VGATE
Gate drive voltage via pull-up resistor
Logic Input Signal
Ground (reference for logic input and power ground)
TYPICAL CHARACTERISTICS (25_C UNLESS NOTED)
N-CHANNEL
VDROP vs. IL
VDROP vs. IL
0.35
0.25
VON/OFF = 2.5 V
VS2 = –4.5 V
IL = –1 A
VON/OFF = 2.5 V
VS2 = –2.5 V
IL = –1 A
0.20
VDROP (V)
VDROP (V)
0.28
0.21
125_C
0.14
0.15
125_C
25_C
0.10
25_C
0.07
0.05
0
0
0
2
4
6
IL (A)
Document Number: 71110
S-00025—Rev. A, 24-Jan-00
8
10
0
1
2
3
4
5
IL (A)
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Si4700DY
New Product
Vishay Siliconix
TYPICAL CHARACTERISTICS (25_C UNLESS NOTED)
VDROP vs. S2
0.10
N-CHANNEL
VDROP Variance vs. Junction Temperature
0.015
VON/OFF = 2.5 V
VS2 = –4.5 V
IL = –1 A
0.012
0.009
VDROP Variance (V)
VDROP (V)
0.08
0.06
VON/OFF = 2.5 V
IL = –1 A
0.04
0.006
0.003
0.000
0.02
–0.003
0
0
2
4
6
8
–0.006
–50
10
–25
0
rDS(on) Variation with Input Voltage
50
75
0.08
0.06
VON/OFF = 2.5 V
IL = –1 A
0.04
0.02
0
150
VON/OFF = 2.5 V
VS2 = –4.5 V
IL = –1 A
1.4
1.2
1.0
2
4
6
8
0.6
–50
10
–25
0
VS2 (V)
25
50
75
VDROP vs. IL
1.0
125
150
P-CHANNEL
VDROP vs. IL
0.70
VON/OFF = 2.5 V
VS1 = 4.5 V
IL = 1 A
VON/OFF = 2.5 V
VS1 = 2.5 V
IL = 1 A
0.56
VDROP (V)
0.8
100
TJ – Junction Temperature (_C)
TYPICAL CHARACTERISTICS (25_C UNLESS NOTED)
VDROP (V)
125
0.8
0
0.6
125_C
0.4
25_C
0.2
0.42
125_C
25_C
0.28
0.14
0
0
0
2
4
6
IL (A)
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100
Normalized rDS(on) vs. Junction Temperature
1.6
r DS(on) – On-Resistance ( )
Normalized
r DS(on) – On-Resistance ( )
0.10
25
TJ – Junction Temperature (_C)
VS2 (V)
8
10
0
1
2
3
4
5
IL (A)
Document Number: 71110
S-00025—Rev. A, 24-Jan-00
Si4700DY
New Product
Vishay Siliconix
TYPICAL CHARACTERISTICS (25_C UNLESS NOTED)
P-CHANNEL
VDROP Variance vs. Junction Temperature
VDROP vs. S1
0.30
0.04
VDROP Variance (V)
VDROP (V)
VON/OFF = 2.5 V
VS1 = 4.5 V
IL = 1 A
0.03
0.24
0.18
VON/OFF = 2.5 V
IL = 1 A
0.12
0.06
0.02
0.01
0.00
–0.01
0
0
2
4
6
8
–0.02
–50
10
–25
rDS(on) Variation with Input Voltage
50
75
100
125
150
Normalized rDS(on) vs. Junction Temperature
0.30
r DS(on) – On-Resistance ( W )
Normalized
1.6
0.24
0.18
VON/OFF = 2.5 V
IL = 1 A
0.12
0.06
VON/OFF = 2.5 V
VS2 = 4.5 V
IL = 1 A
1.4
1.2
1.0
0.8
0
0
2
4
6
8
0.6
–50
10
VS2 (V)
–25
0
25
50
75
100
125
150
TJ – Junction Temperature (_C)
td(on) Variation with RG/VS1
trise Variation with RG/VS1
8
1.5
VS! = 2.5 V
VON/OFF = 3 V
VG = 12 V
CO = 10 mF
IL = 1 A
6
VS! = 2.5 V
Time ( m S)
1.2
Time ( m S)
25
TJ – Junction Temperature (_C)
VS2 (V)
r DS(on) – On-Resistance ( W )
0
0.9
VS! = 3.3 V
0.6
VS! = 3.3 V
4
VS! = 5 V
VS! = 5 V
2
VON/OFF = 3 V
VG = 12 V
CO = 10 mF
IL = 1 A
0.3
0
0
0
20
40
60
RG (kW)
Document Number: 71110
S-00025—Rev. A, 24-Jan-00
80
100
0
20
40
60
80
100
RG (kW)
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Si4700DY
New Product
Vishay Siliconix
TYPICAL CHARACTERISTICS (25_C UNLESS NOTED)
P-CHANNEL
td(off) Variation with RG/VS1
tf Variation with RG/VS1
100
200
VON/OFF = 3 V
VG = 12 V
CO = 10 mF
IL = 1 A
VON/OFF = 3 V
VG = 12 V
CO = 10 mF
IL = 1 A
160
Time ( m S)
Time ( m S)
80
60
VS! = 2.5 V
VS! = 3.3 V
40
VS! = 2.5 V
120
VS! = 3.3 V
80
VS! = 5 V
20
40
VS! = 5 V
0
0
0
20
40
60
80
100
0
20
40
RG (kW)
60
80
100
RG (kW)
TYPICAL CHARACTERISTICS (25_C UNLESS NOTED)
ALL CHANNELS
Normalized Thermal Transient Impedance, Junction-to-Ambient
2
Normalized Effective Transient
Thermal Impedance
1
Duty Cycle = 0.5
0.2
Notes:
0.1
0.1
PDM
0.05
t1
t2
1. Duty Cycle, D =
t1
t2
2. Per Unit Base = RthJA = 82_C/W
0.02
3. TJM – TA = PDMZthJA(t)
Single Pulse
0.01
10–4
4. Surface Mounted
10–3
10–2
10–1
1
10
100
600
Square Wave Pulse Duration (sec)
Normalized Thermal Transient Impedance, Junction-to-Foot
Normalized Effective Transient
Thermal Impedance
2
1
Duty Cycle = 0.5
0.2
0.1
0.1
0.05
0.02
Single Pulse
0.01
10–4
10–3
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10–2
10–1
Square Wave Pulse Duration (sec)
1
10
Document Number: 71110
S-00025—Rev. A, 24-Jan-00
Si4700DY
New Product
Vishay Siliconix
The Si4700 is designed to be used to select one of two power
sources for a circuit, such as needed to implement ACPI in
desktop computers. In this application, parts of the circuit must
run off an always-on power supply when the computer is in
suspend mode. When in normal mode, these circuits run off
the main power supply.
The Si4700DY contains an n-channel MOSFET and a
p-channel MOSFET switch connected together to make a
single-pole, double-throw switch. An additional on-board small
signal MOSFET provides a ground referenced logic input.
When the control input is high, the power MOSFET gates are
pulled to ground, and the p-channel MOSFET is on. When the
input is low, the gates are pulled above the supply rail, and the
n-channel MOSFET is on (pulling the gate of the p-channel
above the source potential has no effect).
The gate drive for the n-channel device, Q1, uses an external
12-V supply via an external resistor. A typical value for this
resistor is around 20 k, but the value is not critical as long as
the current in Q3 is kept below 0.05 A. A higher value of
resistance reduces the current while in suspend mode, but
also introduces a longer delay when turning on Q1.
The Si4700DY switch is a break-before-make configuration,
therefore sufficient capacitance must be present on the
isolated load to ensure hold up during switching. Due to fast
switching times this should not be significant and is preferred
over a make-before-break that would connect the two power
supplies directly for a short period.
Note that the n-channel MOSFET is oriented to ensure that the
internal diode does not conduct while the sub-circuit is
isolated. In this direction it also provides a fail-safe path for the
circuit’s power through the diode. The forward drop of the
p-channel MOSFET’s diode will block any current
back-feeding the secondary supply, assuming the two
supplies are very close in voltage.
The Si4700DY has a maximum rDS(on) of 30 m for the
n-channel MOSFET used during normal operation and 70 m
for the p-channel used when the computer is in suspend,
making it ideal for loads up to 3 A or higher depending on
voltage drop requirements. It can be used on any rail voltage
between 2.5 V and 8 V (based on an absolute max of 12 V),
with a logic input between 2.5-V and 5-V nominal.
Seconday supply
(always on)
SPDT switch required to isolate circuit and connect to VSTANDBY
Main power supply shutdown
control in ATX power supply
Main Supply
ACPI Control
Main
Circuit
Always-On
Circuit
FIGURE 1. ACPI Power Switching Application
Document Number: 71110
S-00025—Rev. A, 24-Jan-00
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Si4700DY
New Product
Vishay Siliconix
+12 V
Si4700DY
Main Supply
Q1
Seconday supply
Load
Q2
Control
Q3
FIGURE 2. Si4700DY used for ACPI Power Switching
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Document Number: 71110
S-00025—Rev. A, 24-Jan-00