SI4779CY-E3 [VISHAY]
Power Management Circuit, PDSO8,;
| 型号： | SI4779CY-E3 |
| 厂家： | 
VISHAY |
| 描述： | Power Management Circuit, PDSO8, 光电二极管 |
| 文件： | 总9页 (文件大小：103K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Si4779CY
Vishay Siliconix
New Product
High-Side N-Channel Switch with Current Limit
FEATURES
APPLICATIONS
D User Set Over Current Limit From 400 mA to 2.4 A
D Low rDS(on) 45 mW (max) at 25_C
D Fault Indicator
D Notebook Computers Power Management
D USB Power Distribution
D Hot Plug In Power Supplies
D Power Supply/Load Protection
D Battery-Charger Circuits
D Under Voltage Lockout
DESCRIPTION
The Si4779CY n-channel high-side switch combines a low
rDS(on) MOSFET switch with a user set, pulse gate control
(PGC) based current limit. This switch is designed to protect
the system power supply from overloads and short circuit
conditions in applications such as USB. The PGC based
approach to the current limiter provides the additional benefit
of keeping the MOSFET junction temperature within
specification, thereby eliminating the need for thermal
shutdown. The low quiescent current makes the Si4779CY
ideal for use in battery powered devices. The Si4779CY
operates on both 3-V and 5-V busses, and is packaged in the
LITTLE FOOTr SO-8 package.
FUNCTIONAL BLOCK DIAGRAM
IN
OUT
–
FAULT
SET
Control
Circuit
V
R
ON
GND
See page 7 for a detailed block diagram.
Document Number: 71664
S-04276—Rev. A, 16-Jul-01
www.vishay.com
1
Si4779CY
New Product
Vishay Siliconix
ABSOLUTE MAXIMUM RATINGS (T = 25_C UNLESS OTHERWISE NOTED)
A
Parameter
Symbol
Steady State
Unit
Voltage, IN to GND
Voltage, ON
V
–0.3 to 7
–0.3 to 7
2.4
IN
V
V
ON
T
= 25rC
= 85rC
= 70rC
A
a
Continuous Drain Current (T = 150rC)
I
D
A
J
T
A
2.4
a
Maximum Power Dissipation
T
A
P
0.65
W
D
Operating Junction and Storage Temperature Range
T, T
j
–65 to 125
_C
stg
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 CONDITIONS
Parameter
Symbol
Steady State
Unit
Voltage, IN to GND
V
3.0 to 5.0
0 to 5.0
0 to 85
IN
V
Voltage, ON or FAULT to GND
Operating Temperature Range
V
, V
ON FAULT
T
A
_C
THERMAL RESISTANCE RATINGS
Parameter
Symbol
Typical
Maximum
Unit
a
Junction-to-Ambient
R
98
37
120
46
thJA
thJF
Steady State
C/W
b
Junction-to-Foot (Drain)
R
Notes
a. Surface mounted on 1” x1” FR4 board, 0.062” thick, 2-oz copper double sided.
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 (R
= R
+ R ). It can also be used to estimate chip temperature if power dissipation and
thPCB-A
thJA
thJF
the lead temperature of a heat carrying (drain) lead is known.
Document Number: 71664
S-04276—Rev. A, 16-Jul-01
www.vishay.com
2
Si4779CY
Vishay Siliconix
New Product
SPECIFICATIONS
Test Conditions Unless Specified
Limits
Typa
Max
Unit
T
= 25_C, V = 5 V
Min
A
IN
Parameter
Basic Operations
Operating Voltage
Symbol
V
2.7
5.5
0.045
0.055
2
V
IN
V
= 4.75 V, I = 2 A
0.035
0.045
IN
D
On-State Resistance
r
W
DS(on)
V
= 3.0 V, I = 2 A
D
IN
I
ON = IN, V = 5.5 V, V
= 0 V
SUP(off)
IN
OUT
Supply Current
mA
I
ON = GND, V = V
= 5.5 V, I = 0 A
OUT
70
SUP(on)
IN
OUT
ON Input Low Voltage
V
V
V
V
= 2.7 to 5.5 V
= 2.7 to 3.6 V
= 4.5 to 5.5 V
0.8
ONL
IN
IN
IN
2.0
2.4
V
ON Input High Voltage
V
ONH
ON Input Current
I
V
= 5.5 V
ON
0.01
"1
mA
ON
Protection
b
Over Current Limit Range
I
Tolerance = "20%, V = 5 V
0.4
2.0
2.4
2.6
A
LIMIT
IN
Under Voltage Lockout (falling edge)
Under Voltage Hysteresis
UVLO
DUVLO
2.3
0.1
V
b
FAULT Output Voltage Low
V
I
= 100 mA
0.4
1
FAULT
SINK
FAULT Logic Output Leakage Current
I
FL
V
= V = 5.5 V
FAULT
0.01
mA
IN
Dynamicb
Turn-On Time
Rise Time
t
t
3
on
V
= 5 V, R = 11 W, C = 40 mF
ms
IN
L
L
t
r
3.5
1.5
0.5
8
Turn-Off Time
Fall Time
off
V
= 5 V, I
= 500 mA
ms
IN
V
OUT
t
f
Cycle Time
t
= 5 V, R = 0.5 W
ms
cyc
IN
L
Notes
a. Typical values at T = 25_C are for DESIGN AID ONLY, not guaranteed nor subject to production testing.
A
b. Guaranteed by design. Derived from I
current ratio, current-limit amplifier and external set resistor accuracy.
SET
TIMING DIAGRAMS
50%
ON
50%
ON
ON
ON
90%
90%
OUT
50%
OUT
50%
10%
10%
OUT
OUT
ton
toff
trise
tfall
FIGURE 1.
FIGURE 2.
Document Number: 71664
S-04276—Rev. A, 16-Jul-01
www.vishay.com
3
Si4779CY
New Product
Vishay Siliconix
TIMING DIAGRAMS
ON
V
RSET
I
LIMIT
tcyc
FIGURE 3.
TYPICAL CHARACTERISTICS (25_C UNLESS NOTED)
R
SET
vs. I
LIMIT
2.5
2.0
1.5
1.0
0.5
0.0
V
= 5 V
IN
R
SET
value is measured in circuit
200
300
400
500
600
700
800
900
1000
1100
(W)
1200
1300
1400
1500
1600
1700
1800
1900
R
SET
Supply Current, Output Disalble vs.
Ambient Temperature Over Operating Voltage
Normalized On-Resistance
vs. Ambient Temperature
1.4
1.2
1.0
0.8
0.6
0.4
1000
100
V
= 5.5 V
IN
10
1
–40
–40 –25 –10
5
20
35
50
65
80
95
–20
0
20
40
60
80
100
T – Ambient Temperature (_C)
A
T – Ambient Temperature (_C)
A
Document Number: 71664
S-04276—Rev. A, 16-Jul-01
www.vishay.com
4
Si4779CY
Vishay Siliconix
New Product
TYPICAL WAVEFORMS (V = 5 V, T = 25_ UNLESS OTHERWISE NOTED)
IN
A
20 ms/div
1 ms/div
CH1: I , 2 A/div
OUT
CH1: I , 0.5 A/div
OUT
CH2: V
CH3: ON, 5 V/div
, 5 V/div, C = 47 mF
CH2: V
CH3: ON, 5 V/div
, 5 V/div, C = 10 mF
OUT
L
OUT L
FIGURE 4. Switch Turn-ON/OFF Time
FIGURE 5. Switch Turn-ON Time
50 ms/div
200 ms/div
CH1: I
CH1: I , 0.5 A/div
OUT
, 0.5 A/div
OUT
CH2: V
CH3: ON, 5 V/div
, 5 V/div, C = 10 mF
CH2: V
CH3: ON, 5 V/div
, 5 V/div, C = 150 mF
OUT
L
OUT L
NOTE: Discharge time based primarily on external R and C
NOTE: Discharge time based primarily on external R and C
FIGURE 6. Switch Turn-OFF Time
FIGURE 7. Switch Turn-OFF Time
Document Number: 71664
S-04276—Rev. A, 16-Jul-01
www.vishay.com
5
Si4779CY
New Product
Vishay Siliconix
TYPICAL WAVEFORMS (V = 5 V, T = 25_ UNLESS OTHERWISE NOTED)
IN
A
2 ms/div
2 ms/div
CH1: ON, 5 V/div
CH2: V , 5 V/div, R = 0.5 W, C = 47 mF
CH1: ON, 5 V/div
CH2: V , 500 mV/div
RESET
OUT
L
L
CH3: FAULT, 5 V/div
CH4: I , 1 A/div
CH3: V
, 5 V/div, R = 5.6 W, C = 100 mF
L L
, 1 A/div
OUT
CH4: I
OUT
OUT
FIGURE 8. FAULT to Short Response (t
)
cyc
FIGURE 9. V
to Over Current Response
RESET
2 ms/div
2 ms/div
CH1: ON, 5 V/div
CH2: PS Droops, 100 mV/div, Offset = 5 V
CH1: ON, 5 V/div
CH2: PS Droops, 50 mV/div, Offset = 5 V
CH3: V
CH4: I
, 1 V/div, R = 0.5 W, C = 100 mF
, 2 A/div
CH3: V
CH4: I
, 1 V/div, R = 0.5 W, C = 100 mF
, 0.5 A/div
OUT
L L
OUT
L L
OUT
OUT
NOTE: Special test with 820-mF capacitor at PS and R
NOTE: Special test with 820-mF capacitor at PS and R
SET
SET
setup for 2.4 A.
setup for 0.5 A.
FIGURE 10. Power Supply Droops vs. Short
FIGURE 11. Power Supply Droops vs. Short
Document Number: 71664
S-04276—Rev. A, 16-Jul-01
www.vishay.com
6
Si4779CY
Vishay Siliconix
New Product
PIN CONFIGURATION
PIN DESCRIPTION
SO-8
Pin Symbol
Description
IN
IN
OUT
1
2
3
4
8
7
6
5
1, 2
3
IN
Input. N-channel MOSFET drain, bypass IN with a 100-mF capacitor to GND.
OUT
Active-low switch-on input, logic low turns switch on. ON needs to be connected to
V during power up, then connect to GND to activate the switch after power up.
IN
Si4778DY
ON
ON
ET
FAULT
GND
4
5
SET
Current-limit input. A resistor from SET to GND sets the current limit for the switch.
Ground
GND
Top View
Fault indicator output. This open drain output goes low when the circuit is in current
limit or in short circuit protection mode.
6
FAULT
OUT
7, 8
Switch output. N-channel MOSFET source.
DETAILED BLOCK DIAGRAM
1
8
IN
OUT
2
IN
7
OUT
–
EA
UVLO
CP
BG
3
ON
QB
S
Q
R
6
+
FAULT
–
D
+
–
4
SET
5
GND
R
SET
FIGURE 12.
Document Number: 71664
S-04276—Rev. A, 16-Jul-01
www.vishay.com
7
Si4779CY
New Product
Vishay Siliconix
DETAILED DESCRIPTION
The SI4779CY limits the output current to a user-defined level.
When the output current passes through the main switch a
fraction of this current passes through a replica switch and
time off is based on average power consumption, which is
designed to be kept under 500 mW.
RSET
.
If the output is shorted , the circuit will go into an on-off cycle
to protect the switch and to prevent the battery from draining
down.
RSET is an external sense resistor used to set the level of the
over current limit; the over current limit should be set between
0.4 A and 2.4 A (see graph for RSET value vs. current limit).
The circuit shuts down the switch when the current flowing
through the switch exceeds Ilimit. After a short period of time,
the circuit will slowly turn on the switch again. The length of
The fault output (FAULT) goes low when the circuit is in over
current limit or short circuit protection mode. A 100-kW pull-up
resistor from FAULT to IN provides a logic-control signal.
APPLICATIONS DIAGRAM
Line Input
Line Output
OUT
IN
100 kW
100 mF
100 kW
FAULT
100 mF
11 W
Si4779CY
ON
ON
SET
GND
R
SET
FIGURE 13.
Document Number: 71664
S-04276—Rev. A, 16-Jul-01
www.vishay.com
8
Legal Disclaimer Notice
Vishay
Notice
Specifications of the products displayed herein are subject to change without notice. Vishay Intertechnology, Inc.,
or anyone on its behalf, assumes no responsibility or liability for any errors or inaccuracies.
Information contained herein is intended to provide a product description only. No license, express or implied, by
estoppel or otherwise, to any intellectual property rights is granted by this document. Except as provided in Vishay's
terms and conditions of sale for such products, Vishay assumes no liability whatsoever, and disclaims any express
or implied warranty, relating to sale and/or use of Vishay products including liability or warranties relating to fitness
for a particular purpose, merchantability, or infringement of any patent, copyright, or other intellectual property right.
The products shown herein are not designed for use in medical, life-saving, or life-sustaining applications.
Customers using or selling these products for use in such applications do so at their own risk and agree to fully
indemnify Vishay for any damages resulting from such improper use or sale.
Document Number: 91000
Revision: 08-Apr-05
www.vishay.com
1
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