LTC4151/LTC4151-1 High Voltage I2C Current and Voltage Monitor FEATURES DESCRIPTION n The LTC®4151 and LTC4151-1 are high side power monitors that operate over a wide voltage range of 7V to 80V. In default operation mode, the onboard 12-bit ADC continuously measures high side current, input voltage and an external voltage. Data is reported through the I2C interface when polled by a host. The monitors can also perform on-demand measurement in a snapshot mode. The LTC4151 features a dedicated shutdown pin to reduce power consumption. The LTC4151-1 features split I2C data pins with data in and an inverted data output to drive optoisolators. n n n n n n n Wide Operating Voltage Range: 7V to 80V 12-Bit Resolution for Both Current and Voltages I2C Interface Additional ADC Input Monitors an External Voltage Continuous Scan and Snapshot Modes Shutdown Mode (LTC4151) Reduces Quiescent Current to 120μA Split SDA for Optoisolation (LTC4151-1) Tiny 10-Lead MSOP and 3mm × 3mm DFN Packages APPLICATIONS n n n n L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Telecom Infrastructure Automotive Industrial Consumer TYPICAL APPLICATION 12-Bit ADC DNL and INL 1.0 High Side Power Sensing with Onboard ADC and I2C 3.3V VOUT SENSE+ SENSE– 2k VIN VDD 2k ADC DNL (LSB) 0.02Ω VIN 7V to 80V 0.5 0 –0.5 μCONTROLLER SHDN LTC4151 SCL SCL ADR1 SDA SDA ADR0 ADIN MEASURED VOLTAGE –1.0 0 1024 2048 3072 CODE 4096 41511 TA01b 1.0 41511 TA01 GND ADC INL (LSB) 0.5 0 –0.5 –1.0 0 1024 2048 CODE 3072 4096 41511 TA01c 41511fa 1 LTC4151/LTC4151-1 ABSOLUTE MAXIMUM RATINGS (Notes 1, 3) VIN Voltage ................................................. –0.3V to 90V SENSE+, SENSE – Voltages .......................... VIN – 10V or –0.3V to VIN + 0.3V ADR1, ADR0 Voltages .............................. –0.3V to 90V ADIN, SHDN, SDAO Voltages ...................... –0.3V to 6V SCL, SDA, SDAI Voltages (Note 2) ........... –0.3V to 5.5V SCL, SDA, SDAI Clamp Current .............................. 5mA Operating Temperature Range LTC4151C/LTC4151C-1 ............................ 0°C to 70°C LTC4151I/LTC4151I-1 ..........................–40°C to 85°C Storage Temperature Range MSOP ................................................–65°C to 150°C DFN....................................................–65°C to 125°C Lead Temperature (Soldering, 10 sec) MSOP Only ....................................................... 300°C PIN CONFIGURATION LTC4151 LT4151 TOP VIEW SENSE+ 1 10 SENSE– VIN 2 9 GND 11 TOP VIEW SENSE+ VIN ADR1 ADR0 ADIN 8 SHDN ADR1 3 ADR0 4 7 SDA ADIN 5 6 SCL 10 9 8 7 6 1 2 3 4 5 SENSE– GND SHDN SDA SCL MS PACKAGE 10-LEAD PLASTIC MSOP TJMAX = 125°C, θJA = 85°C/W DD PACKAGE 10-LEAD (3mm s 3mm) PLASTIC DFN TJMAX = 125°C, θJA = 45°C/W EXPOSED PAD (PIN 11) PCB GND CONNECTION OPTIONAL LTC4151-1 LTC4151-1 TOP VIEW SENSE+ 1 10 SENSE– VIN 2 9 GND 11 8 SDAO ADR1 3 ADR0 4 7 SDAI ADIN 5 6 SCL DD PACKAGE 10-LEAD (3mm s 3mm) PLASTIC DFN TOP VIEW SENSE+ VIN ADR1 ADR0 ADIN 1 2 3 4 5 10 9 8 7 6 SENSE– GND SDAO SDAI SCL MS PACKAGE 10-LEAD PLASTIC MSOP TJMAX = 125°C, θJA = 85°C/W TJMAX = 125°C, θJA = 45°C/W EXPOSED PAD (PIN 11) PCB GND CONNECTION OPTIONAL 41511fa 2 LTC4151/LTC4151-1 ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC4151CDD#PBF LTC4151CDD#TRPBF LCWZ 10-Lead (3mm x 3mm) Plastic DFN 0°C to 70°C LTC4151IDD#PBF LTC4151IDD#TRPBF LCWZ 10-Lead (3mm x 3mm) Plastic DFN –40°C to 85°C LTC4151CDD-1#PBF LTC4151CDD-1#TRPBF LCXC 10-Lead (3mm x 3mm) Plastic DFN 0°C to 70°C LTC4151IDD-1#PBF LTC4151IDD-1#TRPBF LCXC 10-Lead (3mm x 3mm) Plastic DFN –40°C to 85°C LTC4151CMS#PBF LTC4151CMS#TRPBF LTCWY 10-Lead Plastic MSOP 0°C to 70°C LTC4151IMS#PBF LTC4151IMS#TRPBF LTCWY 10-Lead Plastic MSOP –40°C to 85°C LTC4151CMS-1#PBF LTC4151CMS-1#TRPBF LTCXB 10-Lead Plastic MSOP 0°C to 70°C LTC4151IMS-1#PBF LTC4151IMS-1#TRPBF LTCXB 10-Lead Plastic MSOP –40°C to 85°C Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. Consult LTC Marketing for information on non-standard lead based finish parts. For more information on lead free part marking, go to: http://www.linear.com/leadfree/ For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/ ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VIN is from 7V to 80V, unless noted. (Note 3) SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS General Supply Voltage l IIN Supply Current VIN = 48V, Normal Operation Mode VIN = 12V, Shutdown Mode l l ISENSE + SENSE+ Input Current VIN, SENSE+, SENSE – = 48V ISENSE – SENSE – Input Current VIN, SENSE+, SENSE – = 48V VSHDN(TH) SHDN Input Threshold ISHDN SHDN Input Current RES VIN 7 80 V 1.2 120 1.7 300 mA μA l 5 9 μA l 0.1 1 μA l 1 1.5 2 V SHDN = 0V l –3 –5 –8 μA Resolution (No Missing Codes) (Note 4) l 12 VFS Full-Scale Voltage (SENSE+ – SENSE – ) VIN ADIN 81.92 102.4 2.048 mV V V LSB LSB Step Size (SENSE+ – SENSE – ) VIN ADIN 20 25 0.5 μV mV mV TUE Total Unadjusted Error (SENSE+ – SENSE – ) VIN (Note 5) ADIN, LTC4151C, LTC4151C-1 ADIN, LTC4151I, LTC4151I-1 l l l l ±1.25 ±1 ±0.75 ±1 VOS Offset Error (SENSE+ – SENSE – ) VIN (Note 6) ADIN l l l ±5 ±6 ±8 LSB LSB LSB INL Integral Nonlinearity (SENSE+ – SENSE – ) VIN (Note 5) ADIN l l l ±3 ±3 ±2 LSB LSB LSB ADC Bits ±1 ±1 ±0.5 % % % % 41511fa 3 LTC4151/LTC4151-1 ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VIN is from 7V to 80V, unless noted. (Note 3) SYMBOL PARAMETER CONDITIONS σT Transition Noise (SENSE+ – SENSE – ) fCONV Conversion Rate (Continuous Mode) tCONV MIN MAX 1.2 0.3 22 VIN ADIN Conversion Time (Snapshot Mode) TYP UNITS μVRMS mVRMS μVRMS l 6 7.5 9 Hz ADIN, VIN l l 53 26 67 33 85 42 ms ms 2 10 (SENSE+ – SENSE – ) RADIN ADIN Pin Input Resistance ADIN = 3V l IADIN ADIN Pin Input Current ADIN = 3V l MΩ ±2 μA I2C Interface VADR(H) ADR0, ADR1 Input High Threshold l 2.3 2.65 2.9 V VADR(L) ADRO, ADRI Input Low Threshold l 0.3 0.6 0.9 V IADR(IN) ADRO, ADRI Input Current ADR0, ADR1 = 0V or 3V ADR0, ADR1 = 0.8V or 2.2V l l ±70 ±8 μA μA VSDA(OL) SDA, SDAO Output Low Voltage ISDA, ISDAO = 8mA l 0.15 0.4 V ISDA,SCL(IN) SDA, SDAI, SDAO, SCL Input Current SDA, SDAI, SDAO, SCL = 5V l 0 ±2 μA VSDA,SCL(TH) SDA, SDAI, SCL Input Threshold VSDA,SCL(CL) SDA, SDAI, SCL Clamp Voltage ISDA , ISDAI, ISCL = 3mA l 1.6 1.8 2 V l 5.5 6.1 6.6 V I2C Interface Timing (Note 4) fSCL(MAX) Maximum SCL Clock Frequency tLOW Minimum SCL Low Period 0.65 1.3 μs tHIGH Minimum SCL High Period 50 600 ns tBUF(MIN) Minimum Bus Free Time Between Stop/ Start Condition 0.12 1.3 μs tHD,STA(MIN) Minimum Hold Time After (Repeated) Start Condition 140 600 ns tSU,STA(MIN) Minimum Repeated Start Condition Set-Up Time 30 600 ns tSU,STO(MIN) Minimum Stop Condition Set-Up Time 30 600 ns tHD,DATI(MIN) Minimum Data Hold Time Input –100 0 ns tHD,DATO(MIN) Minimum Data Hold Time Output 300 600 900 ns 30 100 ns 50 110 250 ns 20 33 tSU,DAT(MIN) Minimum Data Set-Up Time Input tSP(MAX) Maximum Suppressed Spike Pulse Width tRST Stuck-Bus Reset Time CX SCL, SDA Input Capacitance 400 SCL or SDA/SDAI Held Low Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: Internal clamps limit the SCL, SDA (LTC4151) and SDAI (LTC4151-1) pins to a minimum of 5.5V. Driving these pins to voltages beyond the clamp may damage the part. The pins can be safely tied to higher voltages through a resistor that limits the current below 5mA. kHz 5 ms 10 pF Note 3: All currents into pins are positive. All voltages are referenced to GND, unless otherwise noted. Note 4: Guaranteed by design and not subject to test. Note 5: Integral nonlinearity and total unadjusted error of VIN are tested between 7V and 80V. Note 6: Offset error of VIN is defined by extrapolating the straight line measured between 7V and 80V. 41511fa 4 LTC4151/LTC4151-1 TYPICAL PERFORMANCE CHARACTERISTICS Supply Current vs Supply Voltage (Normal Mode) Supply Current vs Supply Voltage (Shutdown Mode) 400 1.15 – 40°C SUPPLY CURRENT (μA) SUPPLY CURRENT (mA) 1.30 25°C 1.00 85°C 0.85 0.70 VIN = 12V, TA = 25°C, unless noted. 40 60 20 SUPPLY VOLTAGE (V) 0 300 – 40°C 85°C 100 0 80 25°C 200 40 60 20 SUPPLY VOLTAGE (V) 0 41511 G01 41511 G02 ADC DNL vs Code (ADIN Voltage) 1.0 0.05 0.5 0.5 –0.05 –0.10 ADC INL (LSB) 1.0 0 0 0 1024 2048 3072 4096 –1.0 0 –0.5 –0.5 0 1024 CODE 2048 –1.0 3072 4096 ADC DNL vs Code (SENSE Voltage) 1 ADC INL (LSB) 1 ADC DNL (LSB) 0.5 0 –1 1024 2048 3072 4096 CODE –2 0 –1 0 1024 2048 3072 4096 CODE 41511 G06 4096 ADC INL vs Code (SENSE Voltage) 2 –0.5 3072 41511 G05 2 0 2048 CODE 1.0 0 1024 41511 G04 ADC Total Unadjusted Error vs Code (SENSE Voltage) –1.0 0 CODE 41511 G03 ADC TOTAL UNADJUSTED ERROR (%) ADC INL vs Code (ADIN Voltage) 0.10 ADC DNL (LSB) ADC TOTAL UNADJUSTED ERROR (%) ADC Total Unadjusted Error vs Code (ADIN Voltage) 80 –2 0 1024 2048 3072 4096 CODE 41511 G07 41511 G08 41511fa 5 LTC4151/LTC4151-1 TYPICAL PERFORMANCE CHARACTERISTICS 0.5 SDA, SDAO Output Low vs Pull-Up Current (VSDA(OL) vs ISDA ) VIN = 12V, TA = 25°C, unless noted. SDA, SDAI, SCL Clamp Voltage vs Load Current 6.3 85°C 0.4 6.2 0.3 – 40°C 0.2 VSDA,SCL(CL) (V) VSDA(OL) (V) 25°C 6.1 – 40°C 6.0 0.1 0 25°C 0 5 10 15 20 ISDA (mA) 85°C 5.9 0.01 0.1 1 10 ILOAD (mA) 41511 G09 41511 G10 PIN FUNCTIONS (DD/MS) SENSE+ (Pin 1): Kelvin Sense of the VIN Pin. See Figure 10 for recommended Kelvin connection. VIN (Pin 2): Supply Voltage Input. Accepts 7V to 80V. The voltage at this pin is monitored by the onboard ADC with a full-scale input range of 102.4V. SENSE+ must be connected to VIN for proper ADC readout. ADR1, ADR0 (Pin 3, Pin 4): I2C Device Address Inputs. Connecting ADR1 and ADR0 to VIN, GND or leaving the pins open configures one of nine possible addresses. See Table 1 in the Applications Information section for details. ADIN (Pin 5): ADC Input. The onboard ADC measures voltage range between 0V and 2.048V. Tie to GND if unused. SCL (Pin 6): I2C Bus Clock Input. Data is shifted in and out at the SDA pin on rising edges of SCL. This pin is driven by an open collector output from a master controller. An external pull-up resistor or current source is required and can be placed between SCL and VIN. The voltage at SCL is internally clamped to 6V (5.5V minimum). SDA (Pin 7, LTC4151 Only): I2C Bus Data Input/Output. Used for shifting in address, command or data bits and sending out data. An external pull-up resistor or current source is required and can be placed between SDA and VIN. The voltage at SDA is internally clamped to 6V (5.5V minimum). SDAI (Pin 7, LTC4151-1 Only): I2C Bus Data Input. Used for shifting in address, command or data bits. This pin is driven by an open collector output from a master controller. An external pull-up resistor or current source is required and can be placed between SDAI and VIN. The voltage at SDAI is internally clamped to 6V (5.5V minimum). SDAO (Pin 8, LTC4151-1 Only): Inverted Serial Bus Data Output. Open-drain output used for sending data back to the master controller or acknowledging a write operation. Data is inverted for convenience of optoisolation. An external pull-up resistor or current source is required. SHDN (Pin 8, LTC4151 Only): Shutdown Input. Internally pulled up to 6.3V. Pull this pin below 1V to force the LTC4151 into shutdown mode. Leave this pin open if unused. GND (Pin 9): Device Ground. SENSE– (Pin 10): High Side Current Sense Input. Connect an external sense resistor between SENSE+ and SENSE–. The differential voltage between SENSE+ and SENSE– is monitored by the onboard ADC with a full-scale sense voltage of 81.92mV. Exposed Pad (Pin 11, DD Package Only): Exposed pad may be left open or connected to device ground (GND). 41511fa 6 LTC4151/LTC4151-1 BLOCK DIAGRAM RS VIN 2 1 10 SENSE+ VIN 8 SENSE– 6.3V INTERNAL POWER 3 SHDN (LTC4151) 4 ADR1 ADR0 5μA + – 25X DECODER SHUTDOWN CONTROL 8 SDAO (LTC4151-1) VREF = 2.048V 735k MUX 12-BIT ADC I2C/ REGISTERS 7 6V SDA/SDAI (LTC4151/ LTC4151-1) 15k 6 6V GND 9 SCL ADIN 5 41511 BD OPERATION The LTC4151/LTC4151-1 accurately monitor high side current and voltages. These devices accept a wide range of input voltages from as low as 7V up to 80V and consume less than 1.7mA quiescent current in normal operation. A shutdown mode is available with the LTC4151 to reduce the quiescent current to less than 300μA by pulling the SHDN pin below 1V. In default continuous scan mode after power-up, the onboard 12-bit analog-to-digital converter (ADC) continuously and sequentially measures the high side differential voltage between SENSE+ (Kelvin sense of VIN) and SENSE– (full-scale 81.92mV) through an internal sense amplifier, the input voltage VIN (full-scale 102.4V) through an internal voltage divider, and the voltage applied to the ADIN pin (full-scale 2.048V). The reference voltage of the ADC is internally set to 2.048V. The digital data obtained by the ADC is stored in the onboard registers. In snapshot mode, the LTC4151/LTC4151-1 can perform on-demand measurement of a selected voltage without the need of continuous polling by a master controller. The snapshot mode is enabled by programming the control register through the I2C interface. A status bit in the data register monitors the ADC’s conversion. When the conversion is completed, the 12-bit digital code of the measured voltage is held in the corresponding data registers. The LTC4151/LTC4151-1 provide an I2C interface to read the ADC data from the data registers and to program the control register. Two three-state pins, ADR0 and ADR1, are used to decode nine device addresses (see Table 1). The LTC4151 features a single SDA pin to handle both input data and output data, while the LTC4151-1 provides separate SDAI (input) and SDAO (inverted output) pins to facilitate optoisolation. 41511fa 7 LTC4151/LTC4151-1 APPLICATIONS INFORMATION The LTC4151/LTC4151-1 offer a compact complete solution for high side power monitoring. With a wide operating voltage range from 7V to 80V, these devices are ideal for a variety of applications including consumer, automotive, industrial and telecom infrastructure. The simple application circuit as shown in Figure 1 provides monitoring of high side current with a 0.02Ω resistor (4.096A in fullscale), input voltage (102.4V in full-scale) and an external voltage (2.048V in full-scale), all with an internal 12-bit resolution ADC. The 12-bit digital code of each measured voltage is stored in two adjacent registers out of the six total data registers A through F, with the eight MSBs in the first register and the four LSBs in the second (Table 2). The data in registers A through F is refreshed at a frequency of 7.5Hz in continuous scan mode. Setting control register bit G4 (Table 6) invokes a test mode that halts updating of these registers so that they can be written to and read from for software testing. The data converter features a snapshot mode allowing users to make one-time measurements of a selected voltage (either the SENSE voltage, VIN voltage, or ADIN voltage). To enable snapshot mode, set control register bit G7 and write the two-bit code of the desired ADC channel to G6 and G5 (Table 6) using a Write Byte command. When the Write Byte command is completed, the ADC measures the selected voltage and a Busy Bit in the LSB data register is set to indicate that the data is not ready. After completing the conversion, the ADC is halted and the Busy Bit is reset to indicate that the data is ready. To make another measurement of the same voltage or to measure another voltage, first disable the snapshot mode for the previous measurement by clearing control bit G7, then re-enable the snapshot mode and write the code of the desired voltage according to the procedure described above. Data Converter The LTC4151/LTC4151-1 feature an onboard, 12-bit analogto-digital converter (ADC) that continuously monitors three voltages in the sequence of (VSENSE+ – VSENSE–) first, VIN second and VADIN third. The differential voltage between SENSE+ and SENSE– is monitored with an 81.92mV fullscale and 20μV resolution that allows accurate measurement of the high side input current. SENSE+ is a Kelvin sense pin for the VIN pin and must be connected to VIN (see Figure 10) for proper ADC readout. The supply voltage at VIN is directly measured with a 102.4V full-scale and 25mV resolution. The voltage at the uncommitted ADIN pin is measured with a 2.048V full-scale and 0.5mV resolution that allows monitoring of any external voltage. 0.02Ω VIN 7V TO 80V 3.3V VOUT 1 10 SENSE+ SENSE– 2k 2 VIN SHDN LTC4151 SCL 3 4 ADR1 SDA ADR0 ADIN 8 VDD 2k μ-Controller 6 SCL 7 SDA 5 VADIN 41511 F01 GND 9 Figure 1. Monitoring High Side Current and Voltages Using the LTC4151 41511fa 8 LTC4151/LTC4151-1 APPLICATIONS INFORMATION I2C Interface The LTC4151/LTC4151-1 feature an I2C-compatible interface to provide access to six ADC data registers and a control register for monitoring the measured voltages. Figure 2 shows a general data transfer format using the I2C. The LTC4151 and LTC4151-1 are read-write slave devices and support SMBus Read Byte, Write Byte, Read Word and Write Word commands. The devices also support Read Page and Write Page commands that allow one to read or write more than two bytes of data. When using SDA a6 - a0 SCL 1-7 the Read Page and Write Page commands, the host need only to issue an initial register address and the internal register address pointer automatically increments by 1 after each byte of data is read or written. After the register address reaches 06h, it will be reset to 00h and continue the increment. Upon a Stop condition, the register address is reset to 00h. If desired, the Read Page and Write Page support can be disabled by clearing control register bit G3. The data formats for the above commands are shown in Figures 3 to 8. b7 - b0 8 9 1-7 b7 - b0 8 9 1-7 8 9 P S START CONDITION ADDRESS R/W ACK DATA ACK DATA ACK STOP CONDITION 41511 F02 Figure 2. General Data Transfer over I2C S ADDRESS W A COMMAND 1 1 0 a3:a0 0 0 X X X X X b2:b0 FROM MASTER TO SLAVE FROM SLAVE TO MASTER S A DATA A P 0 b7:b0 0 41511 F03 A: ACKNOWLEDGE (LOW) A: NOT ACKNOWLEDGE (HIGH) R: READ BIT (HIGH) ADDRESS W A COMMAND 1 1 0 a3:a0 0 0 X X X X X b2:b0 A DATA A DATA A P 0 b7:b0 0 b7:b0 0 41511 F04 W: WRITE BIT (LOW) S: START CONDITION P: STOP CONDITION Figure 4. LTC4151 Serial Bus SDA Write Word Protocol Figure 3. LTC4151 Serial Bus SDA Write Byte Protocol S ADDRESS W A COMMAND 1 1 0 a3:a0 0 0 X X X X X b2:b0 A DATA A DATA A ... DATA 0 b7:b0 0 b7:b0 0 ... b7:b0 0 A P S ADDRESS W A COMMAND 1 1 0 a3:a0 0 0 X X X X X b2:b0 ADDRESS 0 1 1 0 a3:a0 1 0 b7:b0 1 41511 F05 41511 F06 Figure 5. LTC4151 Serial Bus SDA Write Page Protocol S ADDRESS W A COMMAND 1 1 0 a3:a0 0 0 X X X X X b2:b0 R A DATA A P A S Figure 6. LTC4151 Serial Bus SDA Read Byte Protocol R A DATA A DATA A P A S ADDRESS 0 1 1 0 a3:a0 1 0 b7:b0 0 b7:b0 1 41511 F07 Figure 7. LTC4151 Serial Bus SDA Read Word Protocol S ADDRESS W A COMMAND 1 1 0 a3:a0 0 0 X X X X X b2:b0 A S ADDRESS R A DATA A DATA ... DATA A P 0 1 1 0 a3:a0 1 0 b7:b0 0 b7:b0 ... b7:b0 1 41511 F08 Figure 8. LTC4151 Serial Bus SDA Read Page Protocol 41511fa 9 LTC4151/LTC4151-1 APPLICATIONS INFORMATION Using Optoisolators with LTC4151-1 Stuck-Bus Reset The LTC4151-1 splits the SDA line into SDAI (input) and SDAO (inverted output) for convenience of optocoupling with a host controller that sits at a different ground level. When using optoisolators with the LTC4151-1, connect the SDAI to the output of the incoming optocoupler and connect the SDAO to the anode of the outgoing optocoupler (see Figure 9). With the outgoing optocoupler clamping SDAO and internal 6V (5.5V minimum) clamps on SDAI and SCL, the pull-up resistors on these three pins can be directly connected to VIN. In this way (with SDAO rather than conventional SDAO), the need for a separate low voltage supply for pull-ups is eliminated. The LTC4151/LTC4151-1 I2C interface features a stuckbus reset timer. The low conditions of the SCL and the SDA/SDAI pins are OR’ed to start the timer. The timer is reset when both SCL and SDA/SDAI are pulled high. If the SCL pin or the SDA/SDAI pin is held low for over 33ms, the stuck-bus timer will expire and the internal I2C state machine will be reset to allow normal communication after the stuck-bus condition is cleared. The stuck-bus timer can be disabled by clearing control register bit G2. I2C Device Addressing Nine distinct I2C bus addresses are configurable using the three-state pins ADR0 and ADR1, as shown in Table 1. Address bits a6, a5 and a4 are configured to (110) and the least significant bit is the R/W bit. In addition, the LTC4151 and LTC4151-1 will respond to a mass write address (1100 110)b for writing to all LTC4151s and LTC4151-1s, regardless of their individual address settings. Start and Stop Conditions When the I2C bus is idle, both SCL and SDA must remain in the high state. A bus master signals the beginning of a transmission with a Start condition by transitioning SDA from high to low while SCL stays high. When the master has finished communicating with the slave, it issues a Stop condition by transitioning SDA from low to high while SCL stays high. The bus is then free for another transmission. RS 0.02Ω 3.3V VIN 48V 1 R1 20k 10 SENSE+ SENSE– SCL 2 4 R3 5.1k R4 0.51k MOCD207M 6 8 1 7 7 6 2 3 5 4 R5 0.51k R6 10k R7 10k VIN LTC4151-1 3 R2 20k SDAI ADR1 SDA0 ADR0 ADIN SCL 8 5 VADIN VDD μ-Controller MOCD207M 1 8 2 3 7 6 4 5 GND SDA 41511 F09 9 Figure 9. Optoisolation of the I2C Interface Between LTC4151-1 and a Microcontroller 41511fa 10 LTC4151/LTC4151-1 APPLICATIONS INFORMATION Acknowledge The acknowledge signal is used for handshaking between the transmitter and the receiver to indicate that the last byte of data was received. The transmitter always releases the SDA line during the acknowledge clock pulse. The LTC4151/LTC4151-1 pull the SDA line low on the 9th clock cycle to acknowledge receipt of the data. If the slave fails to acknowledge by leaving SDA high, then the master can abort the transmission by generating a Stop condition. When the master is receiving data from the slave, the master must pull down the SDA line during the clock pulse to indicate receipt of a data byte, and that another byte is to be read. After the last byte has been received the master will leave the SDA line high (not acknowledge) and issue a Stop condition to terminate the transmission. Write Protocol The master begins a write operation with a Start condition followed by the seven bit slave address and the R/W bit set to zero. After the addressed LTC4151/LTC4151-1 acknowledge the address byte, the master then sends a command byte which indicates which internal register the master wishes to write. The LTC4151/LTC4151-1 acknowledge this and then latches the lower three bits of the command byte into its internal register address pointer. The master then delivers the data byte and the LTC4151 or LTC4151-1 acknowledges once more and latches the data into its internal register. If the master continues sending a second byte or more data bytes, as in a Write Word or Write Page command, the second byte or more data bytes will be acknowledged by the LTC4151/LTC4151-1, the internal register address pointer will increment automatically, and each byte of data will be latched into an internal register corresponding to the address pointer. The write operation terminates and the register address pointer resets to 00h when the master sends a Stop condition. Read Protocol The master begins a read operation with a Start condition followed by the seven bit slave address and the R/W bit set to zero. After the addressed LTC4151/LTC4151-1 acknowledge the address byte, the master then sends a command byte that indicates which internal register the master wishes to read. The LTC4151/LTC4151-1 acknowledge this and then latches the lower three bits of the command byte into its internal register address pointer. The master then sends a repeated Start condition followed by the same seven bit address with the R/W bit now set to one. The LTC4151/ LTC4151-1 acknowledge and send the contents of the requested register. The transmission terminates when the master sends a Stop condition. If the master acknowledges the transmitted data byte, as in a Read Word command, the LTC4151/LTC4151-1 will send the contents of the next register. If the master acknowledges the second data byte Table 1. LTC4151/LTC4151-1 Device Addressing* DESCRIPTION HEX DEVICE ADDRESS h a6 a5 Mass Write CC 1 1 0 CE 1 1 1 D0 1 1 2 D2 1 1 3 D4 1 1 4 D6 1 1 5 D8 1 1 6 DA 1 1 7 DC 1 1 8 DE 1 1 *H = Tie High; L = Tie to GND; NC = Open; X = Don’t Care LTC4151/LTC4151-1 ADDRESS PINS BINARY DEVICE ADDRESS a4 0 0 0 0 0 0 0 0 0 0 a3 0 0 1 1 1 1 1 1 1 1 a2 1 1 0 0 0 0 1 1 1 1 a1 1 1 0 0 1 1 0 0 1 1 a0 0 1 0 1 0 1 0 1 0 1 R/W 0 X X X X X X X X X ADR1 X H NC H NC NC L H L L ADR0 X L H H NC L H NC NC L 41511fa 11 LTC4151/LTC4151-1 APPLICATIONS INFORMATION Table 2. LTC4151/LTC4151-1 Register Address and Contents REGISTER ADDRESS* REGISTER NAME READ/WRITE 00h SENSE (A) R/W** ADC Current Sense Voltage Data (8 MSBs) 01h SENSE (B) R/W** ADC Current Sense Voltage Data (4 LSBs) 02h VIN (C) R/W** ADC VIN Voltage Data (8 MSBs) 03h VIN (D) R/W** ADC VIN Voltage Data (4 LSBs) 04h ADIN (E) R/W** ADC ADIN Voltage Data (8 MSBs) 05h ADIN (F) R/W** 06h CONTROL (G) 07h Reserved R/W DESCRIPTION ADC ADIN Voltage Data (4 LSBs) Controls ADC Operation Mode and Test Mode *Register address MSBs b7-b3 are ignored. **Writable if bit G4 is set. Table 3. SENSE Registers A (00h) and B (O1h)—Read/Write BIT NAME OPERATION A7:0, B7:4 SENSE Voltage Data 12-Bit Data of Current Sense Voltage with 20μV LSB and 81.92mV Full-Scale B3 ADC Busy in Snapshot Mode 1 = SENSE Being Converted; 0 = SENSE Conversion Completed. Not Writable B2:0 Reserved Always Returns 0. Not Writable Table 4. VIN Registers C (02h) and D (O3h)—Read/Write BIT NAME OPERATION C7:0, D7:4 VIN Voltage Data 12-Bit Data of VIN Voltage with 25mV LSB and 102.4V Full-Scale D3 ADC Busy in Snapshot Mode 1 = VIN Being Converted; 0 = VIN Conversion Completed. Not Writable D2:0 Reserved Always Returns 0, Not Writable Table 5. ADIN Registers E (04h) and F (O5h)—Read/Write BIT NAME OPERATION E7:0, F7:4 ADIN Voltage Data 12-Bit Data of Current Sense Voltage with 500μV LSB and 2.048V Full-Scale F3 ADC Busy in Snapshot Mode 1 = ADIN Being Converted; 0 = ADIN Conversion Completed. Not Writable F2:0 Reserved Always Returns 0, Not Writable Table 6. CONTROL Register G (06h)—Read/Write BIT NAME OPERATION G7 ADC Snapshot Mode Enable G6 ADC Channel Label for Snapshot Mode ADC Channel Label for Snapshot Mode Enables ADC Snapshot Mode; 1 = Snapshot Mode Enabled. Only the channel selected by G6 and G5 is measured by the ADC. After the conversion, the channel busy bit is reset and the ADC is halted. 0 = Snapshot Mode Disabled (ADC free running, Default). ADC Channel Label for Snapshot Mode G5 G6 0 0 1 G5 0 1 0 ADC CHANNEL SENSE (Default) VIN ADIN G4 Test Mode Enable G3 Page Read/Write Enable Test Mode Halts ADC Operation and Enables Writes to ADC Registers; 1 = Enable Test Mode, 0 = Disable Test Mode (Default) Enables Page Read/Write; 1 = Enable I2C Page Read/Write (Default), 0 = Disable I2C Page Read/Write G2 Stuck-Bus Timer Enable Enables I2C Stuck-Bus Reset Timer; 1 = Enable Stuck-Bus Timer (Default), 0 = Disable Stuck-Bus Timer G1:0 Reserved Always Returns 0, Not Writable 41511fa 12 LTC4151/LTC4151-1 APPLICATIONS INFORMATION and each of the following (if more) data bytes, as in a Read Page command, the LTC4151/LTC4151-1 will keep sending out each data byte in the register that corresponds to the incrementing register pointer. The read operation terminates and the register address pointer resets to 00h when the master sends a Stop condition. VIN ILOAD RS SENSE+ SENSE– VIN GND LTC4151 Layout Considerations ADR1 A Kelvin connection between the sense resistor RS and the LTC4151/LTC4151-1 is recommended to achieve accurate current sensing (Figure 10). The minimum trace width for 1oz copper foil is 0.02" per amp to make sure the trace stays at a reasonable temperature. Using 0.03" per amp or wider is recommended. Note that 1oz copper exhibits a sheet resistance of about 530μΩ per square. ADR0 ILOAD GND 41511 F10 Figure 10. Recommended Layout for Kelvin Connection TYPICAL APPLICATION Temperature Monitoring with an NTC Thermistor While Measuring Load Current and LTC4151 Supply Current 0.2Ω VIN 48V VISHAY 2381 615 4.104 100k AT 25°C 1% SENSE+ SENSE – VIN 250mA LOAD SCL I2C 40.2k 1% LTC4151 SDA ADIN ADR1 1.5k 1% GND ADR0 41511 TA02 T(°C) = 58.82 × (NADIN /NVIN – 0.1066), 20°C < T < 60°C. NADIN and NVIN are digital codes measured by the ADC at the ADIN and VIN pins, respectively. 41511fa 13 LTC4151/LTC4151-1 PACKAGE DESCRIPTION DD Package 10-Lead Plastic DFN (3mm × 3mm) (Reference LTC DWG # 05-08-1699) R = 0.115 TYP 6 0.38 ± 0.10 10 0.675 ±0.05 3.50 ±0.05 1.65 ±0.05 2.15 ±0.05 (2 SIDES) 3.00 ±0.10 (4 SIDES) PACKAGE OUTLINE 1.65 ± 0.10 (2 SIDES) PIN 1 TOP MARK (SEE NOTE 6) (DD) DFN 1103 5 0.200 REF 0.25 ± 0.05 0.50 BSC 2.38 ±0.05 (2 SIDES) 1 0.25 ± 0.05 0.50 BSC 0.75 ±0.05 0.00 – 0.05 2.38 ±0.10 (2 SIDES) BOTTOM VIEW—EXPOSED PAD RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS NOTE: 1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WEED-2). CHECK THE LTC WEBSITE DATA SHEET FOR CURRENT STATUS OF VARIATION ASSIGNMENT 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE 41511fa 14 LTC4151/LTC4151-1 MS Package 10-Lead Plastic MSOP (Reference LTC DWG # 05-08-1661) 0.889 ± 0.127 (.035 ± .005) 5.23 (.206) MIN 3.20 – 3.45 (.126 – .136) 3.00 ± 0.102 (.118 ± .004) (NOTE 3) 0.50 0.305 ± 0.038 (.0197) (.0120 ± .0015) BSC TYP RECOMMENDED SOLDER PAD LAYOUT 0.254 (.010) 10 9 8 7 6 3.00 ± 0.102 (.118 ± .004) (NOTE 4) 4.90 ± 0.152 (.193 ± .006) DETAIL “A” 0.497 ± 0.076 (.0196 ± .003) REF 0° – 6° TYP GAUGE PLANE 1 2 3 4 5 0.53 ± 0.152 (.021 ± .006) DETAIL “A” 0.86 (.034) REF 1.10 (.043) MAX 0.18 (.007) SEATING PLANE 0.17 – 0.27 (.007 – .011) TYP 0.50 (.0197) BSC 0.1016 ± 0.0508 (.004 ± .002) MSOP (MS) 0307 REV E NOTE: 1. DIMENSIONS IN MILLIMETER/(INCH) 2. DRAWING NOT TO SCALE 3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX 41511fa 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. 15 LTC4151/LTC4151-1 TYPICAL APPLICATION High Side Current, Input Voltage and Open Fuse Monitoring with a Single LTC4151 VIN1 48V F1 D1 F2 D2 RS 0.02Ω VIN2 48V D3 D4 R1 150k R2 301k SENSE+ SENSE– VIN SCL LTC4151 SDA ADR1 ADIN R3 3.4k I2C V+ LOAD V– ADR0 GND GND 41511 TA02 CONDITION RESULT NADIN ≥ 1.375 • NVIN Normal Operation 0.835 • NVIN ≤ NADIN < 1.375 • NVIN F2 is Open 0.285 • NVIN ≤ NADIN < 0.835 • NVIN F1 is Open (Not Responding) Both F1 and F2 are Open VIN1 and VIN2 are within 20% apart. NADIN and NVIN are digital codes measured by the ADC at the ADIN and VIN pins, respectively. RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LTC2451 16-Bit I2C Ultra Tiny Delta Sigma ADC Single-Ended Input, 0 to VCC Input Range, 60Hz Output Rate, 3mm × 2mm DFN-8 Package LTC2453 16-Bit I2C Ultra Tiny Delta Sigma ADC Differential Input, ±VCC Input Range, 60Hz Output Rate, 3mm × 2mm DFN-8 Package LTC2970 Power Supply Monitor and Margining Controller 14-Bit ADC Monitoring Current and Voltages, Supplies from 8V to 15V LTC4215 Positive Hot Swap Controller with ADC and I2C 8-Bit ADC Monitoring Current and Voltages, Supplies from 2.9V to 15V TM LTC4260 Positive High Voltage Hot Swap Controller with ADC and I2C 8-Bit ADC Monitoring Current and Voltages, Supplies from 8.5V to 80V LTC4261/ LTC4261-2 Negative High Voltage Hot Swap Controller with ADC and I2C 10-Bit ADC Monitoring Current and Voltages, Supplies from –12V LTC6101/ LTC6101HV High Voltage, High Side Current Sense Amplifier in SOT-23 Package Supplies from 4V to 60V (LTC6101) and 5V to 100V (LTC6101HV) Hot Swap and No Latency Delta Sigma are trademarks of Linear Technology Corporation. 41511fa 16 Linear Technology Corporation LT 0109 REV A • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com © LINEAR TECHNOLOGY CORPORATION 2008