9-4688; Rev 4; 6/11 2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication Features The DS2775–DS2778 report available capacity for rechargeable lithium-ion (Li+) and Li+ polymer (Li-Poly) batteries in mAh and as a percentage of full. Safe operation is ensured by the integrated Li+ protector. The DS2776/DS2778 support SHA-1-based challengeresponse authentication in addition to all other DS2775/ DS2777 features.
DS2775/DS2776/DS2777/DS2778 2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication ABSOLUTE MAXIMUM RATINGS Continuous Sink Current, PIO, DQ......................................20mA Continuous Sink Current, CC, DC.......................................10mA Operating Temperature Range ...........................-20°C to +70°C Storage Temperature Range .............................-55°C to +125°C Lead Temperature (soldering, 10s) .................................
2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication (VDD = +4.0V to +9.2V, TA = -20°C to +70°C, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER SYMBOL CONDITIONS MIN DQ, PIO, SDA Output Logic-Low VOL I OL = 4mA DQ, PIO Pullup Current I PU Sleep mode, VPIN = (VDD - 0.4V) 30 DQ, PIO, SDA, SCL Pulldown Current I PD Active mode, V PIN = 0.
DS2775/DS2776/DS2777/DS2778 2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication EEPROM RELIABILITY SPECIFICATION (VDD = +4.0V to +9.2V, TA = -20°C to +70°C, unless otherwise noted.) PARAMETER SYMBOL EEPROM Copy Time tEEC EEPROM Copy Endurance NEEC CONDITIONS TA = +50°C MIN TYP MAX UNITS 10 ms 50,000 Cycles ELECTRICAL CHARACTERISTICS: 1-Wire INTERFACE, STANDARD (DS2775/DS2776 ONLY) (VDD = +4.0V to +9.2V, TA = -20°C to +70°C.
2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication (VDD = +4.0V to +9.2V, TA = -20°C to +70°C.) PARAMETER SYMBOL SCL Clock Frequency f SCL Bus-Free Time Between a STOP and START Condition tBUF Hold Time (Repeated) START Condition tHD:STA CONDITIONS (Note 4) (Note 5) MIN 0 TYP MAX UNITS 400 kHz 1.3 μs 0.6 μs Low Period of SCL Clock tLOW 1.3 μs High Period of SCL Clock tHIGH 0.6 μs Setup Time for a Repeated START Condition t SU:STA 0.
Typical Operating Characteristics (TA = +25°C, unless otherwise noted.
2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication CURRENT MEASUREMENT ACCURACY 6 1 5 -25 0 LSB (1.5625μV) +25°C 25 DS2775/6/7/8 toc09 2 DS2775/6/7/8 toc08 -20°C 1kΩ RESISTOR FROM PLS TO PK+ IRC (mA) ACCURACY (μV) 75 7 DS2775/6/7/8 toc07 125 CURRENT MEASUREMENT OFFSET vs. TEMPERATURE IRC vs. VDD 4 3 +70°C -1 -2 2 -3 1 -4 -75 -125 -0.052 0 -0.032 -0.012 0.008 VSNS (mV) 0.028 0.
2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication DS2775/DS2776/DS2777/DS2778 Pin Configuration TOP VIEW CC VDD DC VIN2 VIN1 VB VSS 1 2 3 4 5 6 7 + DS2775 DS2776 DS2777 DS2778 EP 14 13 12 11 10 9 8 CP SRC SCL/OVD SDA/DQ PLS PIO SNS TDFN (3mm × 5mm) Pin Description 8 PIN NAME FUNCTION 1 CC Charge Control. Charge FET control output. 2 VDD Chip-Supply Input. Bypass with 0.1μF to VSS. 3 DC Discharge Control. Discharge FET control output.
2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication VOLTAGE POWER-MODE CONTROL PLS DC CURRENT 15-BIT + SIGN ADC SNS PRECISION ANALOG OSCILLATOR VREF VSS TEMPERATURE VIN1 FET DRIVERS CONTROL AND STATUS REGISTERS CP VDD VIN2 Li+ PROTECTOR FuelPack™ ALGORITHM CC 10-BIT + SIGN ADC/MUX PIO LOGIC CHARGE PUMP 32-BYTE PARAMETER EEPROM VOLTAGE REGULATOR COMMUNICATION INTERFACE PIN DRIVERS AND POWER SWITCH CONTROL SDA/DQ SCL/OVD PIO 16-BYTE USER EEPROM VB
2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication DS2775/DS2776/DS2777/DS2778 DS2775/DS2776 Typical Application Circuit PK+ 1kΩ 1kΩ PLS 150Ω DATA 470Ω CC SRC DC 1kΩ VDD VIN2 DQ VB CP 0.47μF VSS OVD SNS 0.1μF 1kΩ VIN1 DS2775 DS2776 PIO 5.1V 150Ω 1kΩ 0.1μF SRC RSNS PK- DS2777/DS2778 Typical Application Circuit PK+ 1kΩ 1kΩ PLS 150Ω SDA SDA SCL SCL 150Ω CC 5.1V 0.1μF SRC 150Ω 1kΩ DC 1kΩ VIN1 DS2777 DS2778 CP 0.
2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication The DS2775–DS2778 function as an accurate fuel gauge, Li+ protector, and SHA-1-based authentication token (SHA-1-based authentication available only on the DS2776/DS2778). The fuel gauge provides accurate estimates of remaining capacity and reports timely voltage, temperature, and current measurement data.
DS2775/DS2776/DS2777/DS2778 2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication ACTIVE PMOD = 0 UVEN = 0 RISING EDGE ON DQ SLEEP PSPIO = 0 PSDQ = 0 ACTIVE PMOD = 0 UVEN = 0 RISING EDGE ON SDA OR SCL SLEEP PSPIO = 0 PSDQ = X CHARGER DETECT CHARGER DETECT VIN1 OR VIN2 < VUV PULL DQ LOW ACTIVE PMOD = 0 UVEN = 1 VIN1 OR VIN2 < VUV SLEEP PSPIO = 0 PSDQ = 1 ACTIVE PMOD = 0 UVEN = 1 RISING EDGE ON SDA OR SCL SLEEP PSPIO = 0 PSDQ = X CHARGER DETECT CHARGER DETECT
2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication ACTIVATION CONDITION RELEASE THRESHOLD THRESHOLD DELAY RESPONSE Overvoltage (OV) (Note 1) VCELL > VOV tOVD CC Off Both VCELL < VCE or (VSNS 1.
DS2775/DS2776/DS2777/DS2778 2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication Undervoltage (UV) If the average of the voltages on (V IN2 - V IN1 ) or (VIN1 - VSS) drops below the undervoltage threshold, VUV, for a period longer than undervoltage delay, tUVD, the DS2775–DS2778 shut off the charge and discharge FETs. If UVEN is set, the DS2775–DS2778 also enter sleep mode.
2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication The DS2775–DS2778 use an integrated temperature sensor to measure battery temperature with a resolution of 0.125°C. Temperature measurements are updated every 440ms and placed in the Temperature register in two’s complement form.
DS2775/DS2776/DS2777/DS2778 2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication Current Offset Correction Current Blanking Every 1024th conversion, the ADC measures its input offset to facilitate offset correction. Offset correction occurs approximately once per hour. The resulting correction factor is applied to the subsequent 1023 measurements. During the offset correction conversion, the ADC does not measure the sense resistor signal.
2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication Sense-Resistor Temperature Compensation The DS2775–DS2778 can temperature compensate the current-sense resistor to correct for variation in a sense resistor’s value over temperature. The DS2775–DS2778 are factory programmed with the sense-resistor temperature coefficient, RSTC, set to zero, which turns off the temperature compensation function.
DS2775/DS2776/DS2777/DS2778 2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication Accumulation Bias Modeling Cell Characteristics In some designs a systematic error or an application preference requires the application of an arbitrary bias to the current accumulation process. The Current Accumulation Bias register (CAB) allows a user-programmed constant positive or negative polarity bias to be included in the current accumulation process.
2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication (R) TEMPERATURE (R) FULL FULL(T) (R) ACTIVE EMPTY AE(T) (R) STANDBY EMPTY SE(T) (R) DS2775/DS2776/DS2777/DS2778 VOLTAGE CAPACITY LOOKUP CURRENT (R) ACCUMULATED CURRENT (ACR) (RW) AVAILABLE CAPACITY CALCULATION ACR HOUSEKEEPING AGE ESTIMATOR AVERAGE CURRENT (R) LEARN FUNCTION REMAINING ACTIVE-ABSOLUTE CAPACITY (RAAC) mAh (R) REMAINING STANDBY-ABSOLUTE CAPACITY (RSAC) mAh (R) REMAINING ACTIVE-RELATIVE C
DS2775/DS2776/DS2777/DS2778 2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication SEGMENT 1 SEGMENT 3 SEGMENT 2 SEGMENT 4 SEGMENT 5 100% FULL DERIVATIVE (ppm/°C) CELL CHARACTERIZATION DATA CHARACTERIZATION ACTIVE EMPTY TBP12 STANDBY EMPTY TBP23 TBP34 +40°C Figure 14. Cell Model Example Diagram read from the Current register.
2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication CELL MODEL PARAMETERS Application Parameters In addition to cell model characteristics, several application parameters are needed to detect the full and empty points, as well as calculate results in mAh units. Sense Resistor Prime (RSNSP) RSNSP stores the value of the sense resistor for use in computing the absolute capacity results. The value is stored as a 1-byte conductance value with units of mhos (1/Ω).
DS2775/DS2776/DS2777/DS2778 2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication Minimum Charge Current (IMIN) IMIN stores the charge-current threshold used to detect a fully charged state. It is stored as a 1-byte value with units of 50µV (IMIN x RSNS) and can range from 0 to 12.75mV. Assuming RSNS = 20mΩ, IMIN can be programmed from 0 to 637.5mA in 2.5mA steps.
2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication ACR Housekeeping The ACR value is adjusted occasionally to maintain the coulomb count within the model curve boundaries. When the battery is charged to full (CHGTF set), the ACR is set equal to the age-scaled full lookup value at the present temperature. If a learn cycle is in progress, correction of the ACR value occurs after the AS is updated.
DS2775/DS2776/DS2777/DS2778 2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication MSB—ADDRESS 02h 215 214 213 212 211 LSB—ADDRESS 03h 210 29 28 MSb 27 LSb 26 25 24 23 22 21 MSb 20 LSb UNITS: 1.6mAh Figure 16. Remaining Active Absolute Capacity (RAAC) [mAh] The RAAC register reports the capacity available under the current temperature conditions to the the active-empty point in absolute units of milliamps/hour (mAh). RAAC is 16 bits.
2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication Protection Register Format The Protection register reports events detected by the Li+ safety circuit on bits [3:2]. Bits 0 and 1 are used to disable the charge and discharge FET gate drivers. Bits [3:2] are set by internal hardware only. Bits 2 and 3 are cleared by hardware only. Bits 0 and 1 are set on power-up and a transition from sleep to active modes.
DS2775/DS2776/DS2777/DS2778 2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication Status Register Format The Status register contains bits that report the device status. All bits are set internally. The CHGTF, AEF, SEF, and LEARNF bits are read-only. Status Register (01h) BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 CHGTF AEF SEF LEARNF X X X X Bit 7: Charge-Termination Flag (CHGTF).
2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication All Control register bits are read and write accessible. The Control register is recalled from parameter EEPROM memory at power-up. Register bit values can be modified in shadow RAM after power-up. Power-up default values are saved by using the Copy Data command.
DS2775/DS2776/DS2777/DS2778 2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication Overvoltage Threshold Register Format The 8-bit Overvoltage Threshold register (VOV) sets the overvoltage threshold for the protection circuitry. An overvoltage condition is detected if either of the voltages on VIN1 or VIN2 exceeds the OV threshold for tOVD. The LSB of the VOV register is 2 x 5V/1024 = 31.25mV. The VOV set point can be calculated by the following formula.
2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication The overcurrent thresholds are set in the upper nibble of the RSGAIN register. The OC1 and OC0 bits set the overcurrent thresholds for the charge and discharge thresholds. The short-circuit threshold is set by the SC0 bit (see Tables 6 and 7, respectively, for overcurrent and short-circuit threshold values). The DS2775–DS2778 have a built-in fixed delay of tOCD for overcurrent events and tSCD for short-circuit events.
DS2775/DS2776/DS2777/DS2778 2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication EEPROM Register The EEPROM register provides access control of the EEPROM blocks. EEPROM blocks can be locked to prevent alteration of data within the block. Locking a block disables write access to the block. Once a block is locked, it cannot be unlocked. Read access to EEPROM blocks is unaffected by the lock/unlock status.
2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication The DS2775–DS2778 have a 256-byte linear memory space with registers for instrumentation, status, and control, as well as EEPROM memory blocks to store parameters and user information. Byte addresses designated as “reserved” typically return FFh when read. These bytes should not be written. Several byte registers are paired into 2-byte registers to store 16-bit values.
DS2775/DS2776/DS2777/DS2778 2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication Table 8.
2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication ADDRESS (HEX) DESCRIPTION READ/WRITE 13h Accumulated Current Register LSB - 2 14h Age Scalar Register R/W* 15h Special Feature Register R/W 16h Full Register MSB R 17h Full Register LSB R 18h Active-Empty Register MSB R R R 19h Active-Empty Register LSB 1Ah Standby-Empty Register MSB R 1Bh Standby-Empty Register LSB R 1Ch Voltage Register MSB, VIN2 - VIN1 R 1Dh Voltage Register LSB, VIN2
DS2775/DS2776/DS2777/DS2778 2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication Challenge command. The host then issues the Compute MAC or Compute MAC with ROM ID command. The MAC is computed per FIPS 180, and then returned as a 160-bit serial stream, beginning with the LSb. DS2776/DS2778 Authentication Commands Write Challenge [0Ch] This command writes the 64-bit challenge to the DS2776/DS2778.
2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication COMMAND HEX FUNCTION Clear Secret 5Ah Clears the 64-bit secret to 0000 0000 0000 0000h. Compute Next Secret without ROM ID 30h Generates new global secret. Compute Next Secret with ROM ID 33h Generates new unique secret. Lock Secret 60h Sets lock bit to prevent changes to the secret. the new secret value to EEPROM. See Figure 26 for command timing.
DS2775/DS2776/DS2777/DS2778 2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication also used to provide verification of error-free data transfer as each EEPROM page is sent to the master during a Read Data/Generate CRC command and for the 8 bytes of information in the status memory field.
2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication Skip Net Address [CCh] This command saves time when there is only one DS2775/DS2776 on the bus by allowing the bus master to issue a function command without specifying the address of the slave. If more than one slave device is present on the bus, a subsequent function command can cause a data collision when all slaves transmit data at the same time.
DS2775/DS2776/DS2777/DS2778 2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication register, address 1Fh, bit 6) to a 1. If the LOCK bit is 0 or if setting the LOCK bit to 1 does not immediately precede the Lock command, the Lock command has no effect. The Lock command is permanent; a locked block can never be written again. Table 12. All Function Commands COMMAND HEX DESCRIPTION Write Challenge 0Ch Writes 64-bit challenge for SHA-1 processing.
2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication DS2775/DS2776/DS2777/DS2778 tSHA 1-Wire RESET WAIT FOR MAC COMPUTATION SKIP-ROM COMMAND PRESENCE PULSE COMPUTE MAC COMMAND UP TO 160 READ TIME SLOTS (READ 20-BYTE MAC) 8 WRITE-ZERO TIME SLOTS Figure 25. Compute MAC Command 1-Wire RESET SKIP-ROM COMMAND PRESENCE PULSE tSHA tEEC WAIT FOR MAC COMPUTATION WAIT FOR EEPROM PROGRAMMING COMPUTE NEXT SECRET COMMAND Figure 26.
DS2775/DS2776/DS2777/DS2778 2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication tEEC 1-Wire RESET SKIP-ROM COMMAND CLEAR/LOCK SECRET COMMAND OR SET/CLEAR OVERDRIVE COMMAND WAIT FOR EEPROM COPY TIME PRESENCE PULSE Figure 28. Clear/Lock Secret, Set/Clear Overdrive Commands tRSTL tRSTH tPDH tPDL PK+ DQ PK- LINE TYPE LEGEND: BUS MASTER ACTIVE LOW DS2775/DS2776 ACTIVE LOW RESISTOR PULLUP Figure 29.
2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication A write time slot is initiated when the bus master pulls the 1-Wire bus from a logic-high (inactive) level to a logic-low level. There are two types of write time slots: write-one and write-zero. All write time slots must be tSLOT in duration with a 1µs minimum recovery time, tREC, between cycles. The DS2775/DS2776 sample the 1-Wire bus line between tLOW1_MAX and tLOW0_MIN after the line falls.
DS2775/DS2776/DS2777/DS2778 2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication WRITE-ZERO SLOT WRITE-ONE SLOT tSLOT tSLOT tLOW0 tLOW1 tREC VPULLUP GND DEVICE SAMPLE WINDOW MIN TYP MAX > 1μs MIN DEVICE SAMPLE WINDOW TYP MAX MODE: STANDARD 15μs 15μs 30μs 15μs 15μs 30μs OVERDRIVE 2μs 1μs 3μs 2μs 1μs 3μs READ-ZERO SLOT tSLOT VPULLUP tRDV READ-ONE SLOT tSLOT tREC tRDV GND > 1μs MASTER SAMPLE WINDOW MASTER SAMPLE WINDOW MODE: STANDARD 15μs 15μ
2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication A byte of data consists of 8 bits ordered MSb first. The LSb of each byte is followed by the acknowledge bit. The DS2777/DS2778 registers composed of multibyte values are ordered MSB first. The MSB of multibyte registers is stored on even data memory addresses. selects a read transaction, with the subsequent bytes being read from the slave by the master.
DS2775/DS2776/DS2777/DS2778 2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication Table 14.
2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication FUNCTION COMMAND TARGET EEPROM BLOCK FCmd VALUE 0 42h 1 44h 0 B2h 1 B4h Copy Data Recall Data 0 63h 1 66h — 39h Lock Read ROM ID DESCRIPTION This command copies the shadow RAM to the target EEPROM block. Copy data commands that target locked blocks are ignored.
DS2775/DS2776/DS2777/DS2778 2-Cell, Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication Revision History PAGES CHANGED REVISION NUMBER REVISION DATE 0 10/08 Initial release — 1 3/09 Corrected values in the VOV Register Programmability table (Table 5) 27 2 7/09 Corrected the 2-wire slave address default value to 1011001 DESCRIPTION 3 5/10 Clarified ESD sensitivity to avoid confusion 4 6/11 Updated the DS2775/DS2776 Typical Application Circuit and DS2777/DS2778
