LTC1710
SMBus Dual Monolithic
High Side Switch
FEATURES
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DESCRIPTION
The LTC
®
1710 SMBus dual switch has two built-in 0.4Ω/
300mA switches that are controlled by a 2-wire SMBus
interface. With a low standby current of 14µA (3.3V), the
LTC1710 operates over an input voltage range of 2.7V to
5.5V while maintaining the SMBus specified 0.6V V
IL
and
1.4V V
IH
input thresholds.
Using the 2-wire interface, CLK and DATA, the LTC1710
follows SMBus’s Send Byte Protocol to independently
control the two 0.4Ω internal N-channel power switches,
which are fully enhanced by onboard charge pumps.
The LTC1710 has one three-state programmable
address pin that allows three different addresses for a total
of six available switches on the same bus. The LTC1710
also features a separate user-controlled drain supply
(SW0D) to Switch 0 so that it can be used to control
SMBus peripherials using a different power supply.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Two 0.4
Ω
/300mA N-Channel Switches
Available in MS8 and SO-8 Packages
SMBus and I
2
C Compatible
0.6V V
IL
and 1.4V V
IH
for DATA and CLK
Low Standby Current: 14µA
Separate Drain Connection to SW0
Three Addresses from One Three-State Address Pin
Independent Control of Up to Six Switches
Built-In Power-On Reset Timer
Built-In Undervoltage Lockout
APPLICATIONS
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Handheld Computer Power Management
Computer Peripheral Control
Laptop Computer Power Plane Switching
Portable Equipment Power Control
Industrial Control Systems
ACPI SMBus Interface
TYPICAL APPLICATION
Switch Voltage Drop
vs Load Current
V
CC
2.7V TO 5.5V
10µF
8
SW0
CLOCK
FROM SMBus
DATA
AD1
(PROGRAMMABLE)
5
6
3
SW1
LTC1710
4
1710 TA01
SW0D
0V TO V
CC
1
500
T
A
= 25°C
SWITCH VOLTAGE DROP (mV)
10µF
400
300
2
CHARGE
PUMP
LOAD 1
200
V
CC
= 2.7V
100
V
CC
= 3.3V
V
CC
= 5V
0
0
200
100
300
LOAD CURRENT (mA)
400
1710 TA02
7
LOAD 2
U
U
U
1
LTC1710
ABSOLUTE
MAXIMUM
RATINGS
(Voltages Referred to GND Pin) (Note 1)
Input Supply Voltage (V
CC
) .......................... – 0.3V to 6V
Input Supply Voltage (V
CC
) with SW0 Connected
as a Low Side Switch ........................... – 0.3V to 3.6V
DATA, CLK (Bus Pins 6, 5)......................... – 0.3V to 6V*
AD1 ( Address Pin 3) ....................... – 0.3V to V
CC
+ 0.3V
OUT0, OUT1 (Output Pins 2, 7) ................... – 0.3V to 6V
SW0D (Switch 0 Drain Pin 1)....................... – 0.3V to 6V
OUT0, OUT1 (Output Pins 2, 7)
Continuous .................................................... 300mA
Pulsed, < 10µs (nonrepetitive) ............................... 1A
PACKAGE/ORDER INFORMATION
TOP VIEW
SW0D
OUT0
AD1
GND
1
2
3
4
8
7
6
5
V
CC
OUT1
DATA
CLK
ORDER PART
NUMBER
SW0D 1
LTC1710CMS8
MS8 PART MARKING
LTDZ
MS8 PACKAGE
8-LEAD PLASTIC MSOP
T
JMAX
= 110°C,
θ
JA
= 150°C/ W
Consult factory for Military grade parts.
ELECTRICAL CHARACTERISTICS
SYMBOL
V
CC
I
VCC
PARAMETER
Operating Supply Voltage Range
Supply Current
T
A
= 25°C, V
CC
= SW0D = 5V unless otherwise noted.
MIN
q
CONDITIONS
Charge Pump Off, AD1 High or Low,
DATA and CLK High
V
CC
= 5V
V
CC
= 3.3V
V
CC
= 2.7V
OUT0 or OUT1 High
(Command Byte XXXXXX01 or XXXXXX10)
Both Outputs High (Command Byte XXXXXX11)
R
DS(ON)
Power Switch On Resistance
V
CC
= 2.7V, I
OUT
= 300mA
V
CC
= 3.3V, I
OUT
= 300mA
V
CC
= 5V, I
OUT
= 300mA
Falling Edge (Note 2)
V
CC
= 2.7V (Note 3)
V
CC
= 5.5V
q
V
UVLO
t
POR
f
OSC
Undervoltage Lockout
Power-On Reset Delay Time
Charge Pump Oscillator Frequency
(Note 3)
2
U
U
W
W W
U
W
Operating Temperature Range
LTC1710C................................................ 0°C to 70°C
LTC1710I ............................................ – 40°C to 85°C
Junction Temperature** ...................................... 125°C
Storage Temperature Range .................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec)................... 300°C
*Supply rails to DATA and CLK are independent of V
CC
to LTC1710.
**Although the LTC1710 can sustain T
JMAX
= 125°C without damage, its internal protection
circuitry is set to shut down the switches at T
J
= 120°C with 15°C hysteresis.
TOP VIEW
8
7
6
5
V
CC
OUT1
DATA
CLK
ORDER PART
NUMBER
LTC1710CS8
LTC1710IS8
S8 PART MARKING
1710
1710I
OUT0 2
AD1 3
GND 4
S8 PACKAGE
8-LEAD PLASTIC SO
T
JMAX
= 110°C,
θ
JA
= 110°C/ W
TYP
MAX
5.5
UNITS
V
2.7
q
q
q
q
q
17
14
11
200
250
0.55
0.46
0.40
1.5
2.0
300
300
300
30
30
30
300
500
0.7
0.6
2.5
1000
1000
µA
µA
µA
µA
µA
Ω
Ω
Ω
V
µs
µs
kHz
LTC1710
ELECTRICAL CHARACTERISTICS
SYMBOL
t
ON
t
OFF
V
IL
V
IH
V
OL
C
IN
I
IN
PARAMETER
Output Turn-On Time
(100Ω/1µF Load)
Output Turn-Off Time
(100Ω/1µF Load)
DATA/CLK Input Low Voltage
AD1 Input Low Voltage
DATA/CLK High Voltage
AD1 Input High Voltage
Data Output Low Voltage
Input Capacitance (DATA, CLK, AD1)
Input Leakage Current (DATA, CLK)
Input Leakage Current (AD1)
SMBus Related Specifications (Note 5)
f
SMB
t
BUF
t
SU:STA
t
HD:STA
t
SU:STO
t
HD: DAT
t
SU:DAT
t
LOW
t
HIGH
t
f
t
r
I
PULL-UP
SMBus Operating Frequency
Bus Free Time Between
Stop and Start
Start Condition Setup Time
Start Condition Hold Time
Stop Condition Setup Time
Data Hold Time
Data Setup Time
Clock Low Period
Clock High Period
Clock/Data Fall Time
Clock/Data Rise Time
Current Through External Pull-Up
Resistor on DATA Pin
CONDITIONS
T
A
= 25°C, V
CC
= SW0D = 5V unless otherwise noted.
MIN
TYP
200
160
250
250
q
q
q
q
q
MAX
UNITS
µs
µs
µs
µs
V
CC
= 2.7V (From ON (Note 6) to V
OUT
= 90% V
CC
)
V
CC
= 5.5V (From ON (Note 6) to V
OUT
= 90% V
CC
)
V
CC
= 2.7V (From OFF (Note 7) to V
OUT
= 10% V
CC
)
V
CC
= 5.5V (From OFF (Note 7) to V
OUT
= 10% V
CC
)
V
CC
= 2.7V to 5.5V
V
CC
= 2.7V to 5.5V
V
CC
= 2.7V to 5.5V
V
CC
= 2.7V to 5.5V
V
CC
= 2.7V to 5.5V, I
PULL-UP
= 350µA
0.6
0.2
1.4
V
CC
– 0.2
0.18
5
0.4
±1
±250
10
4.7
4.7
4.0
4.0
300
250
4.7
4.0
50
300
1000
100
V
V
V
V
V
pF
µA
nA
kHz
µs
µs
µs
µs
ns
ns
µs
µs
ns
ns
µA
q
q
V
CC
= 2.7V to 5.5V
(Open-Drain Data Pull-Down Current Capacity)
100
350
The
q
denotes specifications which apply over the full operating
temperature range.
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2:
Approximately 3% hysteresis is provided to ensure stable operation
and eliminate false triggering by minor V
CC
glitches.
Note 3:
Measured from V
CC
> V
UVLO
to SMBus ready for DATA input.
Note 4:
The oscillator frequency is not tested directly but is inferred from
turn-on time.
Note 5:
SMBus timing specifications are guaranteed but not tested.
Note 6:
ON is enabled upon receiving the Stop condition from the SMBus
master.
Note 7:
OFF is enabled upon receiving the Stop condition from the SMBus
master.
3
LTC1710
TYPICAL PERFOR A CE CHARACTERISTICS
Standby Current vs Temperature
50
500
V
CC
= 5V
STANDBY CURRENT (µA)
40
SUPPLY CURRENT (µA)
SUPPLY CURRENT (µA)
30
V
CC
= 3.3V
20
V
CC
= 5V
10
V
CC
= 2.7V
0
– 50
50
0
TEMPERATURE (°C)
Switch R
DS(ON)
vs Temperature
(SO-8 Package)
1.0
0.9
0.8
SWITCH R
DS(ON)
(Ω)
I
OUT
= 300mA
0.6
0.5
0.4
0.3
0.2
0.1
0
– 50
V
CC
= 2.7V
V
CC
= 3.3V
V
CC
= 5V
0.6
0.5
0.4
0.3
0.2
0.1
V
CC
= 2.7V
V
CC
= 3.3V
V
CC
= 5V
DATA ACK V
OL
(mV)
0.7
SWITCH R
DS(ON)
(Ω)
0
50
TEMPERATURE (°C)
PIN FUNCTIONS
SW0D (Pin 1):
Drain Supply of Switch 0. User-program-
mable from 0V to V
CC
.
OUT0 (Pin 2):
Source Output of Switch 0. Maximum load
of 300mA; controlled by LSB of command byte.
AD1 (Pin 3):
Three-State Programmable Address Pin.
Must be connected directly to V
CC
, GND or V
CC
/2 (using
two resistors
≤1M).
Do not float this pin.
GND (Pin 4):
Ground Connection.
CLK (Pin 5):
Serial Clock Interface. Must be pulled high to
V
CC
with external resistor. The pull-up current must be
limited to 350µA.
DATA (Pin 6):
Open-Drain Connected Serial Data Inter-
face. Must be pulled high to V
CC
with external resistor. The
pull-up current must be limited to 350µA.
OUT1 (Pin 7):
Source Output of Switch 1. Maximum load
of 300mA; controlled by 2nd LSB of command byte.
V
CC
(Pin 8):
Input Supply Voltage. Operating range from
2.7V to 5.5V.
4
U W
1710 G01
1710 G04
Supply Current (I
Q
)
vs Temperature
500
Supply Current (I
Q
)
vs Supply Voltage
T
A
= 25°C
400
400
300
BOTH SW ON
200
SW1 ON
100
SW0 ON
300
BOTH SW ON
200
SW1 ON
SW0 ON
100
100
0
– 50
0
50
0
TEMPERATURE (°C)
100
1710 G02
0
2
4
6
SUPPLY VOLTAGE (V)
8
1710 G03
Switch R
DS(ON)
vs Temperature
(MSOP Package)
1.0
0.9
0.8
0.7
I
OUT
= 300mA
400
Data ACK V
OL
vs Temperature
I
PULL-UP
= 350µA
300
200
100
100
0
0
20
60
40
TEMPERATURE (°C)
80
100
1710 G05
0
– 50
50
TEMPERATURE (°C)
0
100
1710 G06
U
U
U
LTC1710
BLOCK DIAGRA
V
CC
8
V
CC
2V
START
AND
STOP
DETECTORS
ACK
DATA 6
INPUT
BUFFERS
CLK 5
SHIFT
REGISTER
LOGIC
A
B
COUNTER
OUTPUT
LATCHES
AD1 3
ADDRESS
DECODER
TI I G DIAGRA
CLK
t
SU:STA
DATA
START
OPERATIO
SMBus Operation
SMBus is a serial bus interface that uses only two bus lines,
DATA and CLK, to control low power peripheral devices in
portable equipment. It consists of masters, also known as
hosts, and slave devices. The master of the SMBus is
always the one to initiate communications to the slave
devices by varying the status of the DATA and CLK lines.
The SMBus specification establishes a set of protocols that
devices on the bus must follow for communications.
W
W
UNDERVOLTAGE
LOCKOUT
POWER-ON
RESET
V
CC
7 OUT1
REGULATED
CHARGE
PUMPS
THERMAL
SHUTDOWN
1 SW0D
2 OUT0
ADDRESS
COMPARATOR
GND
4
1710 BD
U
UW
t
HD:STA
t
HIGH
t
SU:DAT
t
r
t
HD:DAT
t
f
t
LOW
t
SU:STO
STOP
1710 TD
The protocol that the LTC1710 uses is the Send Byte Pro-
tocol. In this protocol, the master first sends out a Start
signal by switching the DATA line from high to low while
CLK is high. (Because there may be more than one master
on the same bus, an arbitration process takes place if two
masters attempt to take control of the DATA line simulta-
neously; the first master that outputs a one while the other
master is zero loses the arbitration and becomes a slave
itself.) Upon detecting this Start signal, all slave devices on
the bus wake up and prepare to shift in the next byte of data.
5
PCB设计
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