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LTC1710 SMBus Dual Monolithic High Side Switch
FEATURES
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DESCRIPTION
The LTC(R)1710 SMBus dual switch has two built-in 0.4/ 300mA switches that are controlled by a 2-wire SMBus interface. With a low standby current of 14A (3.3V), the LTC1710 operates over an input voltage range of 2.7V to 5.5V while maintaining the SMBus specified 0.6V VIL and 1.4V VIH input thresholds. Using the 2-wire interface, CLK and DATA, the LTC1710 follows SMBus's Send Byte Protocol to independently control the two 0.4 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 0.4/300mA N-Channel Switches Available in MS8 and SO-8 Packages SMBus and I2C Compatible 0.6V VIL and 1.4V VIH for DATA and CLK Low Standby Current: 14A 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
VCC 2.7V TO 5.5V 10F 8 SW0 CLOCK FROM SMBus DATA AD1 (PROGRAMMABLE) 5 6 3 SW1 LTC1710 4
1710 TA01
SW0D 0V TO VCC 1
500
TA = 25C
SWITCH VOLTAGE DROP (mV)
10F
400
300
2 CHARGE PUMP
LOAD 1
200 VCC = 2.7V 100 VCC = 3.3V VCC = 5V 0 0 200 100 300 LOAD CURRENT (mA) 400
1710 TA02
7
LOAD 2
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1
LTC1710
ABSOLUTE MAXIMUM RATINGS
(Voltages Referred to GND Pin) (Note 1)
Input Supply Voltage (VCC) .......................... - 0.3V to 6V Input Supply Voltage (VCC) 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 VCC + 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, < 10s (nonrepetitive) ............................... 1A
PACKAGE/ORDER INFORMATION
TOP VIEW SW0D OUT0 AD1 GND 1 2 3 4 8 7 6 5 VCC OUT1 DATA CLK
ORDER PART NUMBER
SW0D 1
LTC1710CMS8 MS8 PART MARKING LTDZ
MS8 PACKAGE 8-LEAD PLASTIC MSOP
TJMAX = 110C, JA = 150C/ W
Consult factory for Military grade parts.
ELECTRICAL CHARACTERISTICS
SYMBOL VCC IVCC PARAMETER Operating Supply Voltage Range Supply Current
TA = 25C, VCC = SW0D = 5V unless otherwise noted.
MIN
q
CONDITIONS Charge Pump Off, AD1 High or Low, DATA and CLK High VCC = 5V VCC = 3.3V VCC = 2.7V OUT0 or OUT1 High (Command Byte XXXXXX01 or XXXXXX10) Both Outputs High (Command Byte XXXXXX11)
RDS(ON)
Power Switch On Resistance
VCC = 2.7V, IOUT = 300mA VCC = 3.3V, IOUT = 300mA VCC = 5V, IOUT = 300mA Falling Edge (Note 2) VCC = 2.7V (Note 3) VCC = 5.5V
q
VUVLO tPOR fOSC
Undervoltage Lockout Power-On Reset Delay Time Charge Pump Oscillator Frequency (Note 3)
2
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WW
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Operating Temperature Range LTC1710C................................................ 0C to 70C LTC1710I ............................................ - 40C to 85C Junction Temperature** ...................................... 125C Storage Temperature Range .................. - 65C to 150C Lead Temperature (Soldering, 10 sec)................... 300C
*Supply rails to DATA and CLK are independent of VCC to LTC1710. **Although the LTC1710 can sustain TJMAX = 125C without damage, its internal protection circuitry is set to shut down the switches at TJ = 120C with 15C hysteresis.
TOP VIEW 8 7 6 5 VCC 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
TJMAX = 110C, JA = 110C/ 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
A A A A A V s s kHz
LTC1710
ELECTRICAL CHARACTERISTICS
SYMBOL tON tOFF VIL VIH VOL CIN IIN PARAMETER Output Turn-On Time (100/1F Load) Output Turn-Off Time (100/1F 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) fSMB tBUF tSU:STA tHD:STA tSU:STO tHD: DAT tSU:DAT tLOW tHIGH tf tr IPULL-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
TA = 25C, VCC = SW0D = 5V unless otherwise noted.
MIN TYP 200 160 250 250
q q q q q
MAX
UNITS s s s s
VCC = 2.7V (From ON (Note 6) to VOUT = 90% VCC) VCC = 5.5V (From ON (Note 6) to VOUT = 90% VCC) VCC = 2.7V (From OFF (Note 7) to VOUT = 10% VCC) VCC = 5.5V (From OFF (Note 7) to VOUT = 10% VCC) VCC = 2.7V to 5.5V VCC = 2.7V to 5.5V VCC = 2.7V to 5.5V VCC = 2.7V to 5.5V VCC = 2.7V to 5.5V, IPULL-UP = 350A
0.6 0.2 1.4 VCC - 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 A nA kHz s s s s ns ns s s ns ns A
q q
VCC = 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 VCC glitches. Note 3: Measured from VCC > VUVLO 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.
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LTC1710 TYPICAL PERFOR A CE CHARACTERISTICS
Standby Current vs Temperature
50 500 VCC = 5V
STANDBY CURRENT (A)
40
SUPPLY CURRENT (A)
SUPPLY CURRENT (A)
30 VCC = 3.3V 20 VCC = 5V
10
VCC = 2.7V
0 - 50
50 0 TEMPERATURE (C)
Switch RDS(ON) vs Temperature (SO-8 Package)
1.0 0.9 0.8
SWITCH RDS(ON) ()
IOUT = 300mA
0.6 0.5 0.4 0.3 0.2 0.1 0 - 50
VCC = 2.7V VCC = 3.3V VCC = 5V
0.6 0.5 0.4 0.3 0.2 0.1
VCC = 2.7V VCC = 3.3V VCC = 5V
DATA ACK VOL (mV)
0.7
SWITCH RDS(ON) ()
0 50 TEMPERATURE (C)
PIN FUNCTIONS
SW0D (Pin 1): Drain Supply of Switch 0. User-programmable from 0V to VCC. 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 VCC, GND or VCC/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 VCC with external resistor. The pull-up current must be limited to 350A. DATA (Pin 6): Open-Drain Connected Serial Data Interface. Must be pulled high to VCC with external resistor. The pull-up current must be limited to 350A. OUT1 (Pin 7): Source Output of Switch 1. Maximum load of 300mA; controlled by 2nd LSB of command byte. VCC (Pin 8): Input Supply Voltage. Operating range from 2.7V to 5.5V.
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UW
1710 G01 1710 G04
Supply Current (IQ) vs Temperature
500
Supply Current (IQ) vs Supply Voltage
TA = 25C 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 RDS(ON) vs Temperature (MSOP Package)
1.0 0.9 0.8 0.7 IOUT = 300mA
400
Data ACK VOL vs Temperature
IPULL-UP = 350A
300
200
100
100
0
0
20
60 40 TEMPERATURE (C)
80
100
1710 G05
0 - 50
0 50 TEMPERATURE (C)
100
1710 G06
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LTC1710
BLOCK DIAGRA
VCC 8 VCC 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
tSU: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.
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UNDERVOLTAGE LOCKOUT POWER-ON RESET VCC 7 OUT1 REGULATED CHARGE PUMPS THERMAL SHUTDOWN 1 SW0D 2 OUT0 ADDRESS COMPARATOR GND 4
1710 BD
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tHD:STA
tHIGH tSU:DAT
tr tHD:DAT
tf
tLOW
tSU:STO
STOP
1710 TD
The protocol that the LTC1710 uses is the Send Byte Protocol. 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 simultaneously; 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.
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LTC1710
OPERATIO
The master then sends out the first byte. The first seven bits of this byte consist of the address of the device that the master wishes to communicate with. The last bit indicates whether the command will be a read (logic one) or write (logic zero). Because the LTC1710 is a slave device that can only be written to by a master, it will ignore the ensuing commands of the master if it wants to read from the LTC1710, even if the address sent by the master matches that of the LTC1710. After reception of the first byte, the slave device (LTC1710) with the matching address then acknowledges the master by pulling the DATA line low before the next rising clock edge. By now all other nonmatching slave devices will have gone back to their original standby states to wait for the next Start signal. Meanwhile, upon receiving the acknowledge from the matching slave, the master then sends out the command byte (see Table 1).
Table 1. Switch Control Table
COMMAND Switch 0 Switch 1 XXXXXX00 SW0 Off SW1 Off XXXXXX01 SW0 On SW1 Off XXXXXX10 SW0 Off SW1 On XXXXXX11 SW0 On SW1 On
After receiving the command byte, the slave device (LTC1710) needs to acknowledge the master again by pulling the DATA line low on the following clock cycle. The master then ends this Send Byte Protocol by sending the Stop signal, which is a transition from low to high on the DATA line while the CLK line is high. Valid data is shifted into the output latch on the last acknowledge signal; the output switch will not turn on, however, until the Stop signal is detected. This double buffering feature of the output latch allows the user to "daisy-chain" multiple SMBus devices such that their outputs are synchronously
START ADDR1 A COMMAND A START ADDR2 A COMMAND A START ADDR3 A COMMAND A STOP
1710 F01
CLK START 1 0 1 1 0 0 0 (PROGRAMMABLE) 0 (WRITE) ACK 0 0 0 0 0 0 1 (SW1 ON) 1 (SW0 ON) ACK STOP
DATA ADDRESS BYTE COMMAND BYTE
1710 TA03
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executed on the Stop signal despite the fact that valid data were loaded into their output latches at different times. An example is shown in Figure 1. If somehow either the Start or the Stop signal is detected in the middle of a byte, the slave device (LTC1710) will regard this as an error and reject all previous data. Address The LTC1710 has an address of 10110XX; the five MSBs are hardwired, but the two LSBs are programmable by the user with the help of a three-state address pin. Refer to Table 2 for the pin configurations and their corresponding addresses.
Table 2. Address Pin Truth Table
AD1 GND VCC /2 VCC ADDRESS 1011000 1011001 1011010
To conserve standby current, it is preferable to tie the address pins to either VCC or GND. If three LTC1710s are needed, then the address pin can be tied to the third state of VCC /2 by using two equal value resistors (1M), see Figure 2.
5V 6 5 DATA CLK VCC SW0D 8 1 1M 2 7 1M
1710 F02
LTC1710 3 4 AD1 GND OUT0 OUT1
LOAD 1
LOAD 2
Figure 2. The LTC1710 Programmed with Address 1011001
EXECUTION OF DATA STORED IN OUTPUT LATCH OF DEVICES WITH ADDR1, ADDR2 AND ADDR3
Figure 1. Daisy-Chain Example Example of Send Byte Protocol to Slave Address 1011000 Turning SW0 and SW1 On
LTC1710
OPERATIO
Charge Pump
To fully enhance the internal N-channel power switches, an internal charge pump is used to boost the gate drive to a maximum of 6V above VCC. The reason for the maximum charge pump output voltage limit is to protect the internal switches from excessive gate overdrive. A feedback network is used to limit the charge pump output once it is 6V above VCC. To prevent the power switches from turning on too fast, an internal current source is placed between the output of the charge pump and the gate of the power switch to control the ramp rate. Since the charge pumps are driving just the gates of the internal switches, only a small amount of current is required. Therefore, all the charge pump capacitors are integrated onboard. The drain of switch 1 is internally connected to VCC, however, the drain of switch 0 is user controlled through Pin 1. In other words, SMBus devices using different power supply voltages can be simultaneously switched by the same LTC1710. Power-On Reset and Undervoltage Lockout The LTC1710 starts up with both gate drives low. An internal power-on reset (POR) signal inhibits operation
TYPICAL APPLICATIONS
The LTC1710, when used with the LT(R)1521-3.3, can switch a regulated 3.3V/300mA supply to a load (Figure 3). Also, with the help of the LT1304-5, the LTC1710 can be
5V 10F 8 5 FROM SMBus 6 3 PROGRAMMABLE VCC CLK DATA SW0D AD1 OUT0 GND 4 OUT1 LTC1710 1 2 SWITCHED 3.3V 7 1F 5 8 VIN VOUT 1 2 3.3V
Figure 3. Low Dropout Regulator Switching a 3.3V/300mA Supply
Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
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until about 300s after VCC crosses the undervoltage lockout threshold (typically 2V). The circuit includes some hysteresis and delay to avoid nuisance resets. Once operation begins, VCC must drop below the threshold for at least 100s to trigger another POR sequence. Input Threshold Anticipating the trend of lower and lower supply voltages, the SMBus is specified with a VIH of 1.4V and a VIL of 0.6V. While some SMBus parts may violate this stringent SMBus specification by specifying a higher VIH value for a corresponding higher input supply voltage, the LTC1710 meets and maintains the constant SMBus input threshold specification throughout the entire supply voltage range of 2.7V to 5.5V. Thermal Shutdown In the unlikely event that either power switch overheats, a thermal shutdown circuit, which is placed closely to the two switches, will activate and turn off the gate drives to both switches. The thermal shutdown circuit has a threshold of 120C with a 15C hysteresis. used to make a boost switching regulator with output disconnect and a low standby current of 22A (Figure 5).
5V 10F 8 5 FROM SMBus 6 3 PROGRAMMABLE VCC CLK DATA AD1 OUT1 GND 4
1710 F04
3.3V 10F 1 SW0D OUT0 2 3.3V LOAD
LT1521-3.3 SHDN SENSE
LTC1710
1.5F
1710 F03
7
5V LOAD
Figure 4. The LTC1710 Switching Two Different Voltage Loads
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LTC1710
TYPICAL APPLICATIONS
3.3V 8 5 FROM SMBus 6 3 PROGRAMMABLE VCC CLK DATA AD1 OUT1 GND 4 499k 7 1 SW0D OUT0 2 3.3V LOAD 10F
Figure 5. Switching Regulator with Low-Battery Detect Using 22A of Standby Current
PACKAGE DESCRIPTION
MS8 Package 8-Lead Plastic MSOP
(LTC DWG # 05-08-1660)
0.118 0.004* (3.00 0.102) 8
0.192 0.004 (4.88 0.10)
0.040 0.006 (1.02 0.15) 0.007 (0.18) 0.021 0.006 (0.53 0.015) 0 - 6 TYP SEATING PLANE 0.012 (0.30) 0.0256 REF (0.65) TYP
* DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE ** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
RELATED PARTS
PART NUMBER LTC1304 LTC1473 LTC1623 DESCRIPTION Micropower DC/DC Converter Dual PowerPathTM Switch Matrix SMBus Dual High Side Switch Controller COMMENTS Low-Battery Detector Active in Shutdown Current Limit Current Limit with Timer Uses External Switches, Two Three-State Address Pins LTC1470/LTC1471 Single and Dual PCMCIA Protected 3.3V/5V VCC Switches
PowerPath is a trademark of Linear Technology Corporation.
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Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408)432-1900 q FAX: (408) 434-0507 q www.linear-tech.com
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LTC1710 22H* 1N5817
+
100F 3 VIN 4 SW SENSE 1 604k LT1304-5 LBI SHDN 7 SHUTDOWN LBO GND 5 *SUMIDA CD54-220
1710 F05
8 2 100k LBO
+
5V 200mA 2200F
Dimensions in inches (millimeters), unless otherwise noted. S8 Package 8-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
0.189 - 0.197* (4.801 - 5.004)
76
5
8
7
6
5
0.118 0.004** (3.00 0.102)
0.228 - 0.244 (5.791 - 6.197)
0.150 - 0.157** (3.810 - 3.988)
1
23
4
1 2 3 4
0.034 0.004 (0.86 0.102)
0.010 - 0.020 x 45 (0.254 - 0.508) 0.008 - 0.010 (0.203 - 0.254)
0.053 - 0.069 (1.346 - 1.752) 0- 8 TYP
0.004 - 0.010 (0.101 - 0.254)
0.006 0.004 (0.15 0.102)
MSOP (MS8) 1197
0.016 - 0.050 0.406 - 1.270
0.014 - 0.019 (0.355 - 0.483)
0.050 (1.270) TYP
*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE **DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
SO8 0996
1710f LT/TP 0998 4K * PRINTED IN USA
(c) LINEAR TECHNOLOGY CORPORATION 1998

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