LTC2959 AD | Alldatasheet

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Rev. 0For more information www.analog.com Document Feedback TYPICAL APPLICATION FEATURES DESCRIPTION Ultra-Low Power Battery Gas Gauge The LT C®2959 is an ultra-low power battery gas gauge that accurately measures charge, voltage, current and temperature. Its wide input voltage range and its low operating current make the LTC2959 suitable for many applications, including duty-cycled systems that operate over long lifetime. A precision coulomb counter integrates current through an external sense resistor connected at any point in the battery current path. A 16-bit ADC can be configured to measure voltage, current, temperature and/or an auxiliary input in single-shot, duty-cycled (1S/52s) or continuous mode (2.5kS/s). The measurements are stored in internal registers accessible via the onboard I2C/SMBus interface. The LTC2959 features programmable high and low thresholds and min/max tracking registers. If a threshold is exceeded, the device sets a flag in the internal status register and communicates an alert using the SMBus alert protocol when configured as such. 48V High-Side Sensing Coulomb Counter Operating Current vs Temperature

APPLICATIONS

n Operating Supply Current <1.0µA n Supply Voltage from 1.8V to 60V n 0V to 60V Sense Voltage for Low-Side or High-Side Sensing n Fast 16-bit ADC Measures Voltage, Current and Temperature n 1% Voltage, Current and Charge Accuracy n No Crystal or other Time Reference Required n Programmable Deadband Prevents Charge Drift n Includes Battery Voltage Watchdog n Includes Precision Temperature Sensor n Programmable Alerts and Min/Max T racking Registers n Auxiliary ADC Input for Sensor Readout n I2C/SMBus Interface n Available in Small 10-Lead 3mm × 2mm DFN Package n Remote Sensors n Energy Harvesting Systems n Low-Power Handheld Products n Power Tools All registered trademarks and trademarks are the property of their respective owners. COULOMB COUNTER ON, ADC OFF V SENSE = 50mV V SENSE = 0mV TEMPERATURE (°C) –50 –25 100 CURRENT (µA)

2959 TA01b

2959 TA01a

1µF100nF 470nF VDD GND 3.3V µP SENSEP SCL SDA GPIO L TC2959 GND SENSEN CFN CFP VREGVDD

Rev. 0 For more information www.analog.com PIN CONFIGURATIONABSOLUTE MAXIMUM RATINGS Operating Ambient Temperature Range (Note 1) TOP VIEW DDB PACKAGE 10-LEAD (3mm × 2mm) PLASTIC DFN TJMAX = 125°C θJA = 43°C/W VDD SENSEP CFP CFN SENSEN GND VREG GPIO SDA SCL6 ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL (MINI) PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC2959IDDB#PBF LTC2959IDDB#TRMPBF LHGK 10-Lead (3mm × 2mm) Plastic DFN –40°C to 85°C TRM = 500 pieces. *Temperature grades are identified by a label on the shipping container . Contact the factory for parts specified with wider operating temperature ranges. Contact the factory for information on lead based finish parts. Tape and reel specifications. Some packages are available in 500 unit reels through designated sales channels with #TRMPBF suffix.

ELECTRICAL CHARACTERISTICS

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS Power Requirements VDD Supply Voltage l 1.8 60 V ISUPPL Y Supply Current (Note 3) Coulomb Counter On, ADC Off, |VSENSE| < 1mV Coulomb Counter On, ADC Off, |VSENSE| > 1mV Coulomb Counter On, ADC On Coulomb Counter Not Counting, ADC Off l l l 0.8 400 800 µA µA µA µA RSENSEN Resistance between SENSEN and GND When Voltage ADC Measures SENSEN Otherwise 400 kΩ GΩ VUVLO Undervoltage Lockout Threshold VDD Falling l 1.35 1.45 1.55 V tSTARTUP Startup Time Fast Ramp Raises VDD Above 1.8V 8 ms Coulomb Counter VSENSE Sense Voltage Differential Input Range VSENSEP – VSENSEN l ±50 mV TCE Total Charge Error (Note 4) 10mV ≤ |VSENSE| ≤ 50mV Continuously 1mV ≤ |VSENSE| ≤ 10mV Continuously 10mV ≤ |VSENSE| ≤ 50mV Pulses with tPULSE > 1ms l l 0.1 0.2 VOS Offset Voltage l ±1 ±10 µV RIDR Differential Input Resistance Across SENSEP and SENSEN 800 kΩ QLSB Charge LSB (Note 5) RSENSE = 50mΩ 533 nAh EDB Deadband Inaccuracy Deadband = 20µV ±10 % The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C (Note 2).

Rev. 0For more information www.analog.com SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS Voltage Measurement ADC VFS Full-Scale Voltage Conversion 62.6 V ∆VLSB Quantization Step Size 1 LSB at 16-Bit Resolution 0.955 mV GAINVDD Gain Error , VDD Channel 1.8V ≤ VDD ≤ 60V l ±1.0 % GAINSENSEN Gain Error , SENSEN Channel 1.8V ≤ SENSEN ≤ 60V l ±1.0 % INLV Integral Nonlinearity l ±2 ±16 LSB tCONVV Voltage Conversion Time 400 µs Current Measurement ADC VFSI Full-Scale Current Conversion SENSEP – SENSEN ±97.5 mV ∆ILSB Quantization Step Size 1 LSB at 16-Bit Resolution 2.975 µV GAINI Current Gain Accuracy l ±1.0 % VOSI Offset 16-Bit LSBs l ±1 ±8 LSB INLI Integral Nonlinearity 16-Bit LSBs l ±2 ±16 LSB Vn RMS Noise 3 LSB tCONVI Current Conversion Time 400 µs Temperature Measurement ADC TFS Full-Scale Temperature l 825 K ∆TLSB Quantization Step Size 1 LSB at 16-Bit Resolution 12.8 mK TUET Temperature Total Unadjusted Error l ±0.5 ±5 K tCONVT Temperature Conversion Time As Part of Round-Robin Cycle 1200 µs GPIO Voltage Input ADC VFS Full-Scale GPIO Input Range Small Input Range Large Input Range ±97.5 1.56 mV V ∆VLSB Quantization Step Size Small Input Range Large Input Range 2.975 47.6 µV µV GAINGPIO Gain Accuracy l ±1.0 % VOSGPIO Offset Small Input Range Large Input Range LSB LSB INLGPIO Integral Nonlinearity Small Input Range Large Input Range ±32 ±32 LSB LSB tCONVGPIO Conversion Time As Part of Round-Robin Cycle 1600 µs Digital Inputs and Digital Outputs VITH Logic Input Threshold VDD ≥ 1.8V l 0.5 1.4 V VOL Low Level Output Voltage (GPIO, SDA) I = 3mA, VDD ≥ 1.8V l 0.4 V IIN Input Leakage (GPIO, SCL, SDA) VIN = 5.5V l 0.001 1 µA CIN Input Capacitance (GPIO, SCL, SDA) (Note 8) l 10 pF tPCC Minimum Charge Complete (CC) Pulse Width 1 µs The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C (Note 2).

Rev. 0 For more information www.analog.com 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: All currents into pins are positive, all voltages are referenced to GND unless otherwise specified. Note 3: Average current flowing into the VDD pin. The coulomb counter supply current is a function of the voltage between its inputs. The ADC supply current depends on the channel that is being measured. During ADC conversions that measure the voltage on VSENSEN (ADC voltage mode and register B[2] to ‘1’), current flows into SENSEN. Typically, during such conversions, ISENSEN = VSENSEN/400kΩ. Note 4: The coulomb counter measures static signals as well as dynamic inputs (current pulses). It may take several short pulses to increment/ decrement the ACR. Note 5: The equivalent charge of an LSB in the accumulated charge register depends on the value of RSENSE: QLSB = 533nAh • (50mΩ/RSENSE). Note 7: CB = Capacitance of one bus line in pF (10pF ≤ CB ≤ 400pF). Note 8: Guaranteed by design, not subject to test. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS I2C Timing Characteristics fSCL(MAX) Maximum SCL Clock Frequency l 400 900 kHz tBUF(MIN) Bus Free Time Between STOP/START l 1.3 µs tSU,STA(MIN) Minimum Repeated START Set-Up Time l 600 ns tHD,STA(MIN) Minimum Hold Time (Repeated) START Condition l 600 ns tSU,STO(MIN) Minimum Set-Up Time for STOP Condition 600 ns ttSU,DAT(MIN) Minimum Data Set-Up Time Input l 100 ns tHD,DATI(MIN) Minimum Data Hold Time Input l 50 ns tHD,DATO Data Hold Time Output l 0.3 0.9 µs tOF Data Output Fall Time (Notes 7,8) l 20 + 0.1 • CB 300 ns Timeout Max Time between Last SCL Clock Edge and SDA Release 51.2 ms The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C (Note 2).

Rev. 0For more information www.analog.com TYPICAL PERFORMANCE CHARACTERISTICS Coulomb Counter Gain vs Temperature Coulomb Counter Offset vs Common Mode Voltage Coulomb Counter Offset vs Temperature Operating Current vs VSENSE Operating Current vs Supply Voltage Operating Current vs Temperature Current ADC Gain Error vs Temperature Voltage ADC Gain Error vs Temperature Temperature Sensor Error vs Temperature V CM = 0V V CM = 60V TEMPERATURE (°C) –50 –25 100 –0.50 –0.25 0.25 0.50 GAIN ERROR (%)

2959 G01

V CM (V) –10 OFFSET (µV)

2959 G02

TEMPERATURE (°C) –50 –25 100 OFFSET (µV)

2959 G03

V SENSE (mV) CURRENT (µA)

2959 G04

TA = 27°C COULOMB COUNTER ON, ADC OFF TA = 27°C VCM = VDD V SENSE = 50mV V SENSE = 0mV V DD (V) CURRENT (µA)

2959 G05

COULOMB COUNTER ON, ADC OFF COULOMB COUNTER ON, ADC OFF V SENSE = 50mV V SENSE = 0mV TEMPERATURE (°C) –50 –25 100 CURRENT (µA)

2959 G06

TEMPERATURE (°C) –50 –25 100 –0.50 –0.25 0.25 0.50 ERROR (%)

2959 G07

TEMPERATURE (°C) –50 –25 100 –0.50 –0.25 0.25 0.50 ERROR (%)

2959 G08

TEMPERATURE (°C) –50 –25 100 ERROR (°C)

2959 G09

Rev. 0 For more information www.analog.com PIN FUNCTIONS VDD (Pin 1): Power supply with a 1.8V to 60V operat - ing range. Can be supplied from the battery directly by connecting to the load/charger side of the sense resistor , or by any other regulated voltage within range. Bypass to GND (pin 10) with a 100nF capacitor . When register B2 = 0, the Voltage ADC digitizes the voltage between this pin and GND. SENSEP (Pin 2): Positive Sense Input. This is the non-inverting current-sense input. For high-side sensing, connect SENSEP to the load and charger side of the sense resistor . For low-side sensing, connect to the battery ter- minal side. The common mode voltage is independent from VDD and can range from 0 to 60V. SENSEN (Pin 5): Negative Sense Input. This is the invert- ing current-sense input. For high-side sensing, connect SENSEN to the battery terminal side of the sense resistor . For low-side sensing, connect to the load and charger side. When register B2 = 1, the Voltage ADC digitizes the voltage between this pin and GND. CFP (Pin 3): Filter Capacitor Positive Input. Connect a 470nF capacitor between CFP and CFN. Do not connect anything else to this pin. CFN (Pin 4): Filter Capacitor Negative Input. Connect a 470nF capacitor between CFP and CFN. Do not connect anything else to this pin. SCL (Pin 6): Serial Bus Clock Input. SDA (Pin 7): Serial Bus Data Input and Output. An external pull-up resistor or current source is required. GPIO (Pin 8): General Purpose Input/Output. Can be configured as an SMBus alert output, a charge complete logic input or an analog input to the ADC, via control register bits [4:3]. At power-up, the pin defaults to ADC input mode with a full-scale range of 1.56V. When con - figured for alert functionality, it conforms to the SMBus alert response protocol and behaves as an open-drain logic output that pulls to GND when any threshold register value is exceeded. When configured as a charge complete input, connect to the charge complete output from the battery charger circuit. A low level at this pin sets the value of the ACR (registers D,E,F , G) to FFFFFFFFh. In ADC input mode, when used to digitize a signal with a high source impedance, connect a 100nF bypass capacitor between GPIO and GND. VREG (Pin 9): Voltage Regulator Output. Bypass with a 1µF capacitor to GND (Pin 10). Do not connect anything else to this pin. GND (Pin 10): Device Ground. For high-side sensing, con- nect directly to the negative battery terminal. For low-side sensing, connect to the load and charger side of the sense resistor . Exposed Pad (Pin 11): Do not connect this pad. For optimal performance, do not solder the exposed pad to the PCB.

2959 TD01

Figure 1. Definition of Timing on I2C Bus

Rev. 0 For more information www.analog.com OPERATION Overview The LTC2959 is an ultra-low power battery fuel gauge designed for a wide range of batteries. Its high-precision coulomb counter keeps track of charge and discharge by measuring the voltage across an external current sensing resistor . The resistor can be inserted at any point in the battery’s current path, accommodating both low-side and high-side sensing configurations. The LTC2959’s supply voltage can range between 1.8V and 60V and can be set independently of the terminal voltages at the sense resistor . Its extremely low operating current allows the LTC2959 to keep track of charge over extended periods of time. The LTC2959 also measures battery voltage, instanta - neous current, its own temperature and an auxiliary input using an internal ADC. Coulomb Counter Charge is the time integral of current. The LTC2959 measures charge by monitoring the voltage developed across an external sense resistor . The differential volt - age between SENSEP and SENSEN is first low-pass fil - tered and then applied to a precision coulomb counter . The coulomb counter integrates and then digitizes the differential voltage, incrementing and decrementing the Accumulated Charge Register (ACR) as needed. The ACR and its programmable thresholds can be read out via the I2C interface. The coulomb counter modulates its operating current as a function of the signal at its differential input. For small input signals, its typical current reduces to below 1µA . Even at those reduced current levels, its high precision and low offset are maintained. The operating current is inde- pendent of the common mode voltage at the SENSE pins. The coulomb counter can be set to do not count mode using register bit C[3]. This stops coulomb counting and prevents the ACR from incrementing/decrementing. In this mode, the operating current is statically low and no longer input dependent. Coulomb Counter Charge Gain The coulomb counter’ s accumulated charge register (ACR) has a fixed LSB of 533nAh and a width of 32 bits. This accommodates a wide variety of batteries; its full scale of 2289Ah should accommodate most large batter- ies, while even a 10mAh full-scale charge can be resolved to well below 0.01%. The choice of the external sense resistor value influences the gain of the coulomb counter . The full-scale value of the ACR is based on an RSENSE with a value of 50mΩ. If sense resistors with a different value are used, the value should be scaled as follows: QBAT,EFF = 50mΩ RSENSE QBAT,DEFAULT Deadbanding In battery gas gauges, an important parameter is the dif- ferential offset (VOS) of the circuitry monitoring the bat - tery charge. This is because coulomb counters essentially integrate forever , and so the charge error correspond - ing to a small offset grows linearly over time. Moreover , for small input voltages (V SENSE), VOS may significantly contribute to the relative charge error . The LTC2959 was designed to have a very low offset (typically 1µV and no more than ±10µV max). Additionally, the LTC2959 has a programmable dead - band: if the absolute value of the average V SENSE over a 0.5s period is smaller than a programmable threshold, the charge measured during that period is not added to the ACR. Using register bits C [7:6], the programmable threshold can be set to 20, 40 or 80µV, or to 0 (no deadbanding). Voltage, Current, Temperature and GPIO ADC The LTC2959 includes a fast, precision, No-Latency Σ∆ analog-to-digital converter , with internal clock and ref - erence circuits. The ADC can be used to monitor the battery voltage via the SENSEN pin or via the V DD pin (in low-side sensing applications); it can also measure

Rev. 0For more information www.analog.com OPERATION the instantaneous current through the sense resistor , the temperature of the chip, as well as the voltage on the GPIO pin. ADC conversions can be triggered in a one-shot, periodi- cal or continuous manner , as set by programming the ADC control register via the I2C interface. Each ADC conversion takes about 400µs to complete. Initiating a single-shot conversion sequence will cause the ADC to execute the following sequence: 1) 400μs ADC startup 2) 400μs voltage conversion 3) 400μs current conversion 4) 400μs temperature conversion 5) 400µs GPIO conversion (optional) 6) ADC power down Afterwards, all data is available in the corresponding reg- isters. To include the GPIO channel into the ADC measure- ments, set register B[4:3] appropriately and configure its full-scale range using B[3]. By default, the ADC operates in sleep mode, in which no conversions are performed. The ADC can also be operated in smart sleep mode, in which the ADC converts voltage, current, temperature (and GPIO) once every 52 seconds. The threshold and min/max registers are also updated, and alerts will trigger appropriately when the LTC2959 is configured as such. The ADC can also be configured to continuously convert voltage or current, or voltage and current alternatively. In a continuous mode, the ADC startup time sequence step only takes place at the very beginning of ADC operation. Measuring a single quantity continuously leads to a sam- pling rate of 2.5kS/s. Voltage ADC Input Range The accuracy of the ADC Voltage channel is only guaran- teed for input voltages between 1.8V and 60V. Power-Up Sequence When V DD rises above a threshold of approximately 1.45V, the LTC2959 generates an internal power-on reset (POR) signal that sets all registers to their default state. In the default state, the coulomb counter is active while the multi-purpose ADC operates in sleep mode. The accumu- lated charge register is set to mid-scale (80000000h) and all ADC channel outputs are set to 0000h. All threshold registers and the min-max tracking registers are set to their default values. The min/max tracking registers of the ADC will update upon completion of the first ADC con - version. The GPIO pin is configured as an analog input; the ALERT and Charge Complete functionalities are not enabled at startup. Preventing Violation of Absolute Maximum Ratings The small size, robustness and low impedance of ceramic capacitors make them an attractive option for the supply bypass capacitor of LTC2959. However , these capacitors can cause problems if the LTC2959 is plugged into a live supply close to its maximum voltage of 65V. The low- loss ceramic capacitor , combined with stray inductance in series with the power source, forms an underdamped tank circuit, and the voltage at the VDD pin or the SENSE pins of the LTC2959 can ring several tens of volts, pos - sibly exceeding the LTC2959 rating and damaging the part. This can be prevented by adding a transient voltage suppression diode to the appropriate pin. Additionally, when operating at high VDD or SENSE volt- ages (>20V), care should be taken not to pull the digital communication pins SCL, SDA and GPIO below their absolute minimum operating voltage of – 0.3V. This may occur , for example, due to differences between the local GND and the GND of the connected microcontrol - ler . This will increase the supply current, and the asso - ciated increase in power dissipation might damage the part. This can be prevented by adding Schottky diodes to these communication lines, connecting the anodes to the LTC2959 GND pin.

Rev. 0 For more information www.analog.com REGISTER MAP REGISTER NAME LETTER BITS R/W DEFAUL T DATA TYPE 00h Status A A7:A0 COR See Below N/A 01h ADC Control B B7:B0 R/W See Below N/A 02h Coulomb Counter Control C C7:C0 R/W See Below N/A 03h Accumulated Charge <31:24> D D7:D0 R/W 80h Unsigned 04h Accumulated Charge <23:16> E E7:E0 R/W 00h Unsigned 05h Accumulated Charge <15:8> F F7:F0 R/W 00h Unsigned 06h Accumulated Charge <7:0> G G7:G0 R/W 00h Unsigned 07h Charge Threshold Low <31:24> H H7:H0 R/W 00 Unsigned 08h Charge Threshold Low <23:16> I I7:I0 R/W 00 Unsigned 09h Charge Threshold Low <15:8> J J7:J0 R/W 00 Unsigned 0Ah Charge Threshold Low <7:0> K K7:K0 R/W 00 Unsigned 0Bh Charge Threshold High <31:24> L L7:L0 R/W FFh Unsigned 0Ch Charge Threshold High <23:16> M M7:M0 R/W FFh Unsigned 0Dh Charge Threshold High <15:8> N N7:N0 R/W FFh Unsigned 0Eh Charge Threshold High <7:0> O O7:O0 R/W FFh Unsigned 0Fh Voltage MSB P P7:P0 R 00h Unsigned 10h Voltage LSB Q Q7:Q0 R 00h Unsigned 11h Voltage Threshold High MSB R R7:R0 R/W FFh Unsigned 12h Voltage Threshold High LSB S S7:S0 R/W FFh Unsigned 13h Voltage Threshold Low MSB T T7:T0 R/W 00h Unsigned 14h Voltage Threshold Low LSB U U7:U0 R/W 00h Unsigned 15h Max Voltage MSB V V7:V0 R/W 00h Unsigned 16h Max Voltage LSB W W7:W0 R/W 00h Unsigned 17h Min Voltage MSB X X7:X0 R/W FFh Unsigned 18h Min Voltage LSB Y Y7:Y0 R/W FFh Unsigned 19h Current MSB Z Z7:Z0 R 00h Signed 1Ah Current LSB AA AA7:AA0 R 00h Signed 1Bh Current Threshold High MSB AB AB7:AB0 R/W 7Fh Signed 1Ch Current Threshold High LSB AC AC7:AC0 R/W FFh Signed 1Dh Current Threshold Low MSB AD AD7:AD0 R/W 80h Signed 1Eh Current Threshold Low LSB AE AE7:AE0 R/W 00h Signed 1Fh Max Current MSB AF AF7:AF0 R/W 80h Signed 20h Max Current LSB AG AG7:AG0 R/W 00h Signed 21h Min Current MSB AH AH7:AH0 R/W 7Fh Signed 22h Min Current MSB AI AI7:AI0 R/W FFh Signed

Rev. 0For more information www.analog.com REGISTER MAP REGISTER NAME LETTER BITS R/W DEFAUL T DATA TYPE 23h Temperature MSB AJ AJ7:AJ0 R 00h Unsigned 24h Temperature LSB AK AK7:AK0 R 00h Unsigned 25h Temperature Threshold High MSB AL AL7:AL0 R/W FFh Unsigned 26h Temperature Threshold High LSBs AM AM7:AM0 R/W FFh Unsigned 27h Temperature Threshold Low MSB AN AN7:AN0 R/W 00h Unsigned 28h Temperature Threshold Low LSBs AO AO7: AO0 R/W 00h Unsigned 29h GPIO Voltage MSB AP AP7:AP0 R 00h Signed 2Ah GPIO Voltage LSB AQ AQ7:AQ0 R 00h Signed 2Bh GPIO Threshold High MSB AR AR7:AR0 R/W 7Fh Signed 2Ch GPIO Threshold High LSB AS AS7:AS0 R/W FFh Signed 2Dh GPIO Threshold Low MSB AT AT7:AT0 R/W 80h Signed 2Eh GPIO Threshold Low LSB AU AU7:AU0 R/W 00h Signed Status (A) 8-bit Table: STATUS Register (00h) (Read-Only – Clear on Read) BIT NAME OPERATION DEFAUL T A7 GPIO Alert Indicates one of the GPIO limits has been exceeded. 0 A6 Current Alert Indicates one of the current limits was exceeded. 0 A5 Charge Overflow/Underflow Indicates that the value of the ACR has hit either top or bottom. 0 A4 Temperature Alert Indicates one of the temperature limits was exceeded. 0 A3 Charge Alert High Indicates the upper charge limit was exceeded. 0 A2 Charge Alert Low Indicates the lower charge limit was exceeded. 0 A1 Voltage Alert Indicates one of the voltage limits was exceeded. 0 A0 UVLO Alert Indicates recovery from power bad. If equal to 1, an UVLO has occurred and the content of registers is uncertain.

Rev. 0 For more information www.analog.com Control (B) 8-bit Table: CONTROL Register (01h) (Read/Write) BIT NAME OPERATION DEFAUL T B[7:5] ADC Mode [000] Sleep; does not convert and does not update any registers. The coulomb counter is still active. [001] Smart Sleep; converts V , I, T every 52 seconds (tolerance < ±5%); if B[4] is high, also converts GPIO. Updates registers and threshold comparators. [010] Continuously convert V (2.5kS/s) [011] Continuously convert I (2.5kS/s) [100] Continuously convert, alternating between V and I [101] Single-shot convert V , I and T; if B[4] is high, appends GPIO conversion after T . Resets to [000] after completing these conversions. [110] Continuously convert V , I and T; if B[4] is high, appends GPIO conversion after T [111] Unused [000] B[4:3] GPIO Configure Configures the GPIO pin. [00] Alert mode; logic output; Alert functionality enabled [01] Charge Complete mode; logic input; driving a logic LOW sets the Accumulated Charge Register to 0xFFFFFFFF . [10] Analog input to ADC with ±97.5mV input voltage range [11] Analog input to ADC with 0V to 1.56V input voltage range [11] B[2] Configure Voltage Input 0: ADC uses VDD as voltage input. 1: ADC uses SENSEN as voltage input. B[1:0] Reserved Reserved [00] Coulomb Counter Configuration (C) 8-bit Table: Coulomb Counter Configuration Register (02h) (Read/Write) BIT NAME OPERATION DEFAUL T C[7:6] Coulomb Counter Sets the VSENSE threshold below which no charge is added to the Accumulated Charge Register . [01] Deadband [00] 0µV (no deadband) [01] 20µV [10] 40µV [11] 80µV C[5:4] Reserved Reserved [01] C[3] Do Not Count Stops coulomb counting and prevents the Accumulated Charge Register from being incremented/decremented. C[2:0] Reserved Reserved [000] REGISTER MAP

Rev. 0For more information www.analog.com APPLICATIONS INFORMATION Internal Registers The LTC2959 register map is shown above. The LTC2959 integrates current through a sense resistor , measures battery charge, voltage, current and temperature (and, optionally, GPIO), and stores the results in internal reg - isters accessible via I2C. Charge is stored in a 32-bit reg- ister , all other quantities are stored in 16-bit registers. High and low thresholds can be programmed for each measured quantity. The voltage and current ADC channels also include minimum and maximum trackers. After each voltage, current, temperature or GPIO con - version, the ADC conversion result is compared to the respective threshold registers. If a value in the threshold registers is exceeded, the corresponding bit in the status register is set (A[7], A[6], A[4] or A[1]). If alert mode is enabled, the GPIO pin pulls low. Analog inputs that exceed the ADC input range will cause overflow or underflow. The corresponding ADC conver - sion result will be the most negative (underflow) or most positive (overflow) output code. Overflow or underflow will also cause the corresponding status alert bit to be set. If alert mode is enabled, the GPIO pin pulls low. The minimum and maximum tracking registers will hold the lowest and the highest value measured since their ini- tialization, respectively. These registers are updated after every voltage ADC or current ADC conversion. The minimum and maximum trackers initialize to the high- est and lowest possible conversion result, respectively, and they can be set via I2C. The accumulated charge register can be configured by writing a target 32-bit value to it via I 2C, or by asserting charge complete (CC). When GPIO is configured in digital input mode and it is pulled low externally, CC is asserted and the ACR will be set to 32’hFFFFFFFF . Coulomb count- ing only resumes when CC is no longer asserted. Do not simultaneously assert charge complete and attempt to write the ACR to a target value over I2C. The ACR is compared to the charge thresholds every time the coulomb counter increments or decrements it. If the ACR value exceeds the threshold register values, the corresponding bits A[3] or A[2] are set. Bit A[5] is set if the ACR overflows or underflows. At each overflow or underflow, the ACR rolls over and resumes integration. All status register bits are cleared after being read by the host but may be reasserted after the next ADC conversion or charge integration, if the corresponding alert condition is still fulfilled. Processing Digital Results The LTC2959 can measure charge, voltage, current and temperature. To calculate the amount of charge represented by the ACR, read out registers D, E, F and G in a single sequen- tial read. Their combined output yields an unsigned 32-bit number , which should be multiplied by the ACR LSB size, QLSB = 533nAh, to obtain the total charge. The result of the 16-bit ADC conversion of the voltage at either VDD or SENSEN (depending on the ADC control settings) is stored in the voltage registers (P , Q). This data is unsigned. From the result of the 16-bit voltage register RESUL T[15:0] = P[7:0]Q[7:0], the measured voltage can be calculated as: VBAT = 62.6V •RESULTdec 65536 The values in the voltage threshold and min/max track - ing registers, registers R, S, T , U, V , W , X ansd Y, are also stored in unsigned notation. As an example, to set the voltage low threshold to 3.72V, write registers T[7:0]U[7:0] to 0F37h. The result of the 16-bit ADC conversion of the current is stored in the current registers (Z, AA). The ADC mea - sures battery current by converting the voltage, V SENSE, across the sense resistor RSENSE. Depending on whether the battery is being charged or discharged, the measured voltage drop on RSENSE is positive or negative. The result in registers Z and AA is stored in signed, two’s complement notation. Bit Z[7] is the sign bit of the result. The battery current can be obtained from the two-byte

  • RESULT[14:0]dec 32768 If RESUL T[15] = 1: IBAT = 97.5mV RSENSE
  • –32768 +RESULT[14:0]dec 32768 The values in the current threshold and min/max tracking registers, register AB, AC, AD, AE, AF , AG, AH and AI, are also stored in signed, two’s complement notation. The internal temperature of the LTC2959 can be calculated by reading out registers AJ and AK. Combining these into RESUL T[15:0] = AJ[7:0]AK[7:0], the device temperature in Celsius is given by: TC = 825•RESULTdec 65536 – 273.15 The ADC can also be configured to measure the analog voltage at the GPIO pin. The full-scale input range can be selected via the ADC control register and is either ±97.5mV or from 0V to 1.56V. In both cases, the result data is stored in registers AP and AQ and in both cases, the data is stored in signed, two’s complement notation. To calculate the analog voltage from the digital result, use the same equations as for the ADC current channel, replacing 97.5mV with 1.56V when the wide full-scale input range is selected (register bit B[3] = 1). APPLICATIONS INFORMATION I2C/SMBus interface The LTC2959 communicates with a bus master using a 2-wire interface compatible with I 2C and SMBus. The 7-bit hardcoded I 2C address of the LTC2959 is 1100011 (0xC6). The LTC2959 is a slave-only device. The serial clock line (SCL) is input-only while the serial data line (SDA) is bidirectional. The device supports I 2C standard and fast mode. For more details, refer to the I2C protocol section. I2C protocol The LTC2959 uses an I 2C/SMBus-compatible 2-wire interface supporting multiple devices on a single bus. Connected devices can only pull the bus lines low and must never drive the bus high. The bus wires are exter - nally connected to a positive supply via current sources or pull-up resistors. When the bus is idle, all bus lines are high. Data on the I2C bus can be transferred at rates of up to 100kbit/s in standard mode and up to 400kbit/s in fast mode. Each device on the I2C/SMBus is recognized by a unique address stored in that device and can operate as either a transmitter or receiver , depending on the function of the device. In addition to transmitters and receivers, devices can also be classified as masters or slaves when perform- ing data transfers. A master is the device which initiates a data transfer on the bus and generates the clock sig - nals to permit that transfer . At the same time any device addressed is considered a slave. The LTC2959 always acts as a slave. SCL SDA START CONDITION STOP CONDITION ADDRESS R/W ACK DATA ACK DATA ACK 1 - 7 8 9

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Figure 2. Data T ransfer Over I2C or SMBus

Rev. 0For more information www.analog.com APPLICATIONS INFORMATION Start and Stop Conditions When the bus is idle, both SCL and SDA must be high. A bus master signals the beginning of a transmission with a START condition by transitioning SDA from high to low while SCL is high. When the master has finished communicating with the slave, it issues a STOP condition by transitioning SDA from low to high while SCL is high. The bus is then free for another transmission. When the bus is in use, it stays busy if a repeated START (Sr) is gen- erated instead of a STOP condition. The repeated START (Sr) conditions are functionally identical to the START (S). Write Protocol The master begins a write operation with a START condi- tion followed by the seven-bit slave address 1100011 and the R/W bit set to zero. The LTC2959 acknowledges this by pulling SDA low and the master sends a command byte which indicates which internal register the master is to write. The LTC2959 acknowledges and latches the com- mand byte into its internal register address pointer . The master delivers the data byte, the LTC2959 acknowledges once more and latches the data into the desired register . The transmission is ended when the master sends a STOP condition. If the master continues by sending a second data byte instead of a stop, the LTC2959 acknowledges again, increments its address pointer and latches the sec- ond data byte in the following register . Multi-byte quantities can only be written using a suffi - ciently long I2C burst write. Read Protocol The master begins a read operation with a START con - dition followed by the seven-bit slave address 1100011 and the R/W bit set to zero. The LTC2959 acknowledges and the master sends a command byte which indicates which internal register the master is to read. The LTC2959 acknowledges and then latches 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 LTC2959 acknowledges and sends the contents of the requested register . The transmission is ended when the master sends a STOP condition. If the master acknowledges the transmitted data byte, the LTC2959 increments its address pointer and sends the contents of the following register . Multi-byte quantities should be read using a sufficiently long I2C burst read. I2C Timeout The device includes a timer to ensure that it does not hold SDA low indefinitely in the absence of a clock. This tim - eout interval is typically 51.2ms. When no clock pulses are received for the duration of this interval, the LTC2959 releases the SDA pin and the communication interface is reset. Alert Response Protocol In a system where several slaves share a common inter- rupt line, the master can use the alert response address (ARA) to determine which device initiated the interrupt. The master initiates the ARA procedure with a START con- dition and the special 7-bit ARA bus address (0001100) followed by the read bit (R) = 1. If the LTC2959 is assert- ing an alert, it acknowledges and responds by sending its 7-bit bus address (1100011) and a 1. While it is sending its address, it monitors the SDA pin to see if another device is sending an address at the same time using standard I2C bus arbitration. If the LTC2959 is sending a 1 and reads a 0 on the SDA pin on the rising edge of SCL, it assumes another device with a lower address is sending and the LTC2959 immediately aborts its transfer and waits for the next ARA cycle to try again. If transfer is successfully completed, the LTC2959 will stop pulling down the GPIO pin and will not respond to further ARA requests until a new Alert event occurs. Reconfiguring the LTC2959’s GPIO pin as an analog or a digital input immediately clears the Alert pull-down. Afterwards, when the GPIO pin is configured as a digital output again, the LTC2959 will only pull down GPIO when a new alert event occurs.

cleared upon readout of the status register . function regardless of I2C communication. with short sense-traces to the SENSEP and SENSEN pins. minimize leakage, do not solder the exposed pad. Figure 3. Kelvin Connection on Sense Resistor

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Rev. 0For more information www.analog.com Information furnished by Analog Devices is believed to be accurate and reliable. However , no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. PACKAGE DESCRIPTION 2.00 ±0.10 (2 SIDES) NOTE: 1. DRAWING CONFORMS TO VERSION (WECD-1) IN JEDEC PACKAGE OUTLINE M0-229 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 0.40 ±0.10 BOTTOM VIEW—EXPOSED PAD 0.64 ±0.05 (2 SIDES) 0.75 ±0.05 R = 0.115 TYPR = 0.05 TYP 2.39 ±0.05 (2 SIDES) 3.00 ±0.10 (2 SIDES) 106 PIN 1 BAR TOP MARK (SEE NOTE 6)

0.200 REF

0 – 0.05 (DDB10) DFN 0905 REV Ø 0.25 ±0.05

0.50 BSC

R = 0.20 OR 0.25 × 45° CHAMFER 0.25 ±0.05 2.39 ±0.05 (2 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS 0.64 ±0.05 (2 SIDES) 1.15 ±0.05 0.70 ±0.05 2.55 ±0.05 PACKAGE OUTLINE 10-Lead Plastic DFN (3mm × 2mm) (Reference LTC DWG # 05-08-1722 Rev Ø)

Rev. 0 For more information www.analog.com  ANALOG DEVICES, INC. 2022 www.analog.com RELATED PARTS TYPICAL APPLICATION 1.13M 14.7k 47k 10k 1.15M 47nF 5m/uni03A9 VOUT 30.4V , 15A33V TO 60V Si7135DP 47k CSN CSP BGATE IGATE BAT OFB FBG BFB NTC CX L TC4000 ITH CC IID 5m/uni03A9 L T3845A 100µF OUT VCSHDN IN RST CLN IN ENC CHRG FLT VM IIMON IBMON 22.1k TMR GND BIASCL 24.9k 1µF 3.0V 1.10M 100k 10nF 10nF 1µF0.1µF Si7135DP 0.5A LOADC1 1µF CHARGER/ LOAD 2kRSENSE 100m/uni03A9 30V LI-ION BATTERY

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1µF100nF 470nF VDD GND 3.3V µP SENSEP SCL SDA GPIO L TC2959 GND SENSEN CFN CFP VREGVDD PART NUMBER DESCRIPTION COMMENTS Battery Gas Gauges LTC2943 I2C Battery Gas Gauge with Voltage, Current and Temperature ADC 3.6V to 20V Operation, 14-Bit ∆∑-ADC, Pin Compatible with LTC2944, LTC2943-1, 8-Lead (3mm × 3mm) DFN Package LTC2944 I2C Battery Gas Gauge with Voltage, Current and Temperature ADC 3.6V to 60V Operation, 14-Bit ∆∑-ADC, Pin Compatible with LTC2943, 8-Lead (3mm × 3mm) DFN Package LTC2941 I2C Battery Gas Gauge 2.7V to 5.5V Operation, 6-Lead (2mm × 3mm) DFN Package LTC2942 I2C Battery Gas Gauge with Temperature, Voltage Measurement 2.7V to 5.5V Operation, 14-Bit ∆∑-ADC, 6-Lead (2mm × 3mm) DFN Package LTC4150 Coulomb Counter/Battery Gas Gauge 2.7V to 8.5V Operation, 10-Pin MSOP Package Battery Chargers LTC4000 High Voltage High Current Controller for Battery Charging and Power Management 3V to 60V Operation, 28-Lead (4mm × 5mm) QFN or SSOP Packages LTC4009 High Efficiency, Multi-Chemistry Battery Charger 6V to 28V Operation, 20-Lead (4mm × 4mm) QFN Package LTC4012 High Efficiency, Multi-Chemistry Battery Charger with PowerPath™ Control 6V to 28V Operation, 20-Lead (4mm × 4mm) QFN Package LT 3652HV Power T racking 2A Battery Charger Input Supply Voltage Regulation Loop for Peak Power T racking, 5V to 34V Operation, 1MHz, 2A Charge Current, 3mm × 3mm DFN-12 and MSOP-12 Packages Battery Charger with Gas Gauge