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SI4788CY
New Product
Vishay Siliconix
5-A Controlled Slew Rate Load Switch with Level Shift
FEATURES
D D D D D D 5-A Maximum Load Switches Voltages 1.8- to 5.5-V Ground Referenced Logic Inputs 1.8- to 5-V Logic Voltage Compatible 25-mW Maximum On-Resistance Level-Shifted Gate Drive Means The Control (Logic) Voltage Is Independent Of Power Voltage D Slow Turn-On (Controlled Slew Rate) Eliminates High Inrush Currents D Low Power Consumption In Off State D Active Pull-Down On Output When In Off State
DESCRIPTION
The SI4788CY is a p-channel MOSFET with a logic interface. The control input is compatible with all types of logic down to 1.8 V. The switch can be used to control voltages from 1.8 V to 5.5 V, and the logic input can be a lower voltage than the power. The switch also incorporates reduced switching speed to reduce inrush when switching loads with a high value of capacitance. The SI4788CY is packaged in an 8-pin SOIC package and rated for the commercial temperature range of 0 to 85_C
FUNCTIONAL BLOCK DIAGRAM AND PIN CONFIGURATION
S
D
IN
Logic and Gate Drive
Document Number: 71100 S-02651--Rev. C, 27-Nov-00
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SI4788CY
Vishay Siliconix
ABSOLUTE MAXIMUM RATINGS
Voltage Referenced to GND VS, VDa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 V to 7.0 V VIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 V to 7.0 V Power Dissipation (Continuous)a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5 W Continuous P-Switch Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 A Storage Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -55 to 150_C Notes a. Device mounted with all leads soldered to 1" x 1" FR4 with laminated copper PC board.
New Product
Stresses beyond 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 in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
RECOMMENDED OPERATING RANGE
VS, VD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.8 V to 5.5 V VIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 V to 5.5 V Operating Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . . . . -25 to 85_C Junction Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -25 to 150_C
This device has a maximum recommended operating junction temperature of 85_C. This temperature limit is used for electrical specifications such as logic transition voltages only and is not a reliability limit. The device can be used with junction temperatures up to 150_C if relaxed specifications can be tolerated, although limits for these specifications may not be given. Performance curves can be used to give an indication of specifications at higher temperatures, but are not guaranteed.
THERMAL RESISTANCE RATINGS
Parameter
Maximum Junction-to-AmbientNO TAG Maximum Junction-to-Foot (Drain)NO TAG Steady State Steady State
Symbol
RthJA RthJF
Typical
80 15
Maximum
95 20
Unit
_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 Symbol Specific Test Conditions
VS = 3.3 V, ID = 1 A, VIN = H VS = 4.5 V, ID = 1 A, VIN = H VS = 3.3 V to 5 V, VIN = L VS = 1.8 V to 5 V, VIN = L VS = 3.3 V to 5 V VS = 1.8 V to 3.3 V VS = 3.3 V to 5 V VS = 1.8 V to 3.3 V
Tempa
Minb
Typc
Maxb
Unit
Room Room Room Room Full Full Full Full Room Room 2.2 1.5 8
20 16 12
25 20 20 1.2 0.6 0.3
On-Resistance Pull-Down Resistance Leakage Current Logic Input Voltage Low
rDS(on) rPULL-DOWN IS(off) VINL VINH td(on) td(off) tRISE tFALL dv/dt
mW W W mA
V
Input Voltage High Turn-On Delay Turn-Off Delay Rise Time Fall Time Maximum Turn-On Slew Rate
16 20 280 920 20
35 40 550 1800 V/ms ms m
VIN = 5 V, ILOAD = 1 A, CLOAD = 100 mF Test Circuit 1
Room Room Room
Notes a. Room = 25_C, Full = as determined by the operating temperature suffix. b. The algebraic convention whereby the most negative value is a minimum and the most positive a maximum. c. Typical values are for DESIGN AID ONLY, not guaranteed nor subject to production testing. www.vishay.com Document Number: 71100 S-02651--Rev. C, 27-Nov-00
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SI4788CY
New Product
TIMING DIAGRAMS
Vishay Siliconix
VS VIN 0V VIN
50%
50%
90% VD VD td(on) tr 10% td(off)
90% 10%
tf
TEST CIRCUIT 1
PIN CONFIGURATION
SO-8
VIN SOURCE SOURCE SOURCE 1 2 3 4 8 7 6 5 GND DRAIN DRAIN DRAIN
TRUTH TABLE
VIN
0 1
Switch
Off On
Top View Order Number: SI4788CY
PIN DESCRIPTION
Pin Number
1 2, 3, 4 5, 6, 7 8
Symbol
VIN SOURCE DRAIN GND
Description
Input pin
Ground
Document Number: 71100 S-02651--Rev. C, 27-Nov-00
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SI4788CY
Vishay Siliconix
New Product
TYPICAL CHARACTERISTICS (25_C UNLESS NOTED)
Input Voltage Trip Point vs. Temperature
1.30 10.000
Total Off-State Leakage Current
TJ = 25_C
1.25 1.000 VIN - Trip Point 1.20 I TOTAL ( mA) VS = 5 V
1.15
0.100 TJ = 150_C
1.10 0.010 1.05 0.001 0
1.00 -50
-25
0
25
50
75
100
125
150
2
4 VS (V)
6
8
10
Temperature (_C)
0.040
On-Resistance vs. VIN Voltage
VS = VIN ID = 1 A
Normalized On-Resistance vs. Junction Temperature
1.4 VS = 4.5 V VIN = 4.5 V ID = 1 A 1.2
r DS(on) - On-Resistance ( W )
0.032
0.024
r DS(on) - On-Resistance ( W ) Normalized 3.5 VS(V) 4.0 4.5 5.0 5.5
1.0
0.016
0.8
0.008
0.000 1.5
2.0
2.5
3.0
0.6 -50
-25
0
25
50
75
100
125
150
TJ - Junction Temperature (_C)
10000
Switching Time vs. Load Capacitance
7000 tfall 6000 trise
Rise Time vs. Temperature
VS = VIN CLOAD = 100 mF ID = 1 A
1000 5000 Time ( mS) ( mS) tdoff 100 tdon 4000 3000 2000 VS = 5 V VIN = 5 V ID = 1 A RLOAD = 5 W 200 400 600 800 1000 1000 0 -50 VS = 3.3 V
10
t RISE
VS = 5.0 V
1 0
-25
0
25
50
75
100
125
150
Load Capacitance (mF)
Temperature (_C)
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Document Number: 71100 S-02651--Rev. C, 27-Nov-00
SI4788CY
New Product
TYPICAL CHARACTERISTICS (25_C UNLESS NOTED)
Turn-On Delay vs. Temperature
100 1100
Vishay Siliconix
Fall Time vs. Temperature
VS = 3.3 V
80 1000
t d(on) ( m s)
40
t fall ( m s)
60
VS = VIN CLOAD = 100 mF ID = 1 A
VS = 5.0 V VS = VIN CLOAD = 100 mF ID = 1 A
900
800
20
VS = 5.0 V
700
VS = 3.3 V
0 -50 -25 0 25 50 75 100 125 150
600 -50 -25 0 25 50 75 100 125 150
Temperature (_C)
Temperature (_C)
Turn-Off Delay vs. Temperature
40
Single Pulse Power
100
32
VS = VIN CLOAD = 100 mF ID = 1 A
80
t d(off) ( m s)
VS = 5.0 V
16
VS = 3.3 V
Power (W)
24
60
40
8
20
0 -50 -25 0 25 50 75 100 125 150
0 0.001 0.01 0.1 1 10
Temperature (_C)
Square Wave Pulse Duration (sec)
Normalized Thermal Transient Impedance, Junction-to-Ambient
2 1 Normalized Effective Transient Thermal Impedance Duty Cycle = 0.5
0.2
Notes:
0.1 0.1 0.05
PDM t1 t2 1. Duty Cycle, D = t1 t2 2. Per Unit Base = RthJA = 80_C/W 3. TJM - TA = PDMZthJA(t) 4. Surface Mounted
0.02 Single Pulse 0.01 10-4 10-3 10-2 10-1 1
10
100
600
Square Wave Pulse Duration (sec)
Document Number: 71100 S-02651--Rev. C, 27-Nov-00
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2-5
SI4788CY
Vishay Siliconix
New Product
TYPICAL CHARACTERISTICS (25_C UNLESS NOTED)
Normalized Thermal Transient Impedance, Junction-to-Foot
2 1 Normalized Effective Transient Thermal Impedance Duty Cycle = 0.5
0.2 0.1 0.1 0.05 0.02
0.01 10-4
Single Pulse 10-3 10-2 10-1 Square Wave Pulse Duration (sec) 1 10
TYPICAL APPLICATIONS
The SI4788CY can be used to control a load up to 5-Amp where the control logic voltage is different from the voltage of the load being controlled, and/or the load has a large capacitive component and inrush currents must be minimized during switching.
therefore compatible with any CMOS logic voltage between 2.2 V and 5 V under these conditions with no extra configuration required. With a 3.3-V power rail voltage the minimum high input voltage is 1.5 V, making it compatible with 1.8-V logic.
The low RDS(on) of 20-mW typical makes the switch ideal for applications such as power bus switching in notebook computers and central office telecom equipment. For a load of 5 A, the voltage drop is only approximately 100 mV.
The control input is a CMOS compatible input with a minimum high input voltage of 2.2 V with a power rail voltage of 5 V. It is
The SI4788CY is designed to give a steady dv/dt on the output during turn-on even with capacitive loads. The output rise time is 280-ms typical with a 100-mF load, which corresponds to a dv/dt of about 20 V/ms, or a capacitive inrush current of around 2-A max with a 100-mF load. Higher values of capacitance result in a slower switching speed, therefore even with very high values of capacitance, inrush should not be a problem.
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Document Number: 71100 S-02651--Rev. C, 27-Nov-00
SI4788CY
New Product
Vishay Siliconix
SI4788CY
5V
Device Bay
SI4788CY
3.3 V
Main Bus
SI4788CY
HDD
DC/DC Converter
Power Management
FIGURE 1. SI4788CY Used To Control 5-V Bus With 3.3-V Logic Control
3.3 V 2.5 V
SI4788CY
DC/DC Converter Power Management
Load
FIGURE 2. SI4788CY Used To Control 3.3-V Bus With 2.5-V Or 3.3-V Logic
Power 56 kW
SI4788CY
"Live Plugged" Load Circuit provides delayed turn-on of the SI4788CY in the Absence of a Power_On signal. 56 kW 0.1 mF
FIGURE 3. SI4788CY Used As Inrush Limiter On Removable Card
Document Number: 71100 S-02651--Rev. C, 27-Nov-00
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