DS2756 Maxim Integrated Products, DS2756 Datasheet
DS2756
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DS2756 Summary of contents
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... GENERAL DESCRIPTION The DS2756 high-precision battery fuel gauge is a data-acquisition and information-storage tailored for cost-sensitive and space-constrained 1- cell Li+/polymer battery-pack DS2756 provides the key hardware components required to accurately estimate remaining capacity by integrating low-power, precision measurements of temperature, voltage, current, accumulation, as well as nonvolatile (NV) data storage, into the small footprint ...
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ABSOLUTE MAXIMUM RATINGS Voltage on PIO Pin, Relative to V Voltage on All Other Pins, Relative to V Continuous Sink Current, DQ, PIO Operating Temperature Range Storage Temperature Range Soldering Temperature This is a stress rating only and functional operation ...
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... Current Gain Error specifies the gain error in the Current register value compared to a reference voltage between IS1 and IS2. The DS2756 does not compensate for sense resistor characteristics, and any error terms arising from the sense resistor should be taken into account when calculating total current measurement error. ...
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... The host system can configure the DS2756 to signal critical conditions to reduce polling overhead. The alarm interrupt fires when programmable upper and lower thresholds of temperature or coulomb count are crossed. The user can select either the DQ pin or PIO pin as the alarm interrupt signal ...
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Figure 2. Functional Diagram 1-WIRE INTERFACE DQ AND ROM ID THERMAL SENSE M U VIN X IS2 SNS DETAILED PIN DESCRIPTION Pin Name Description Battery Voltage-Sense Input. Voltage measurement performed Voltage Register. Device Ground ...
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... The DS2756 returns to Active mode from Suspend or Sleep mode whenever the DQ line is pulled from a low-to- high state. The factory default for the DS2756 is UVEN = 0, PMOD = 0 and PIE = 00b. The DS2756 defaults to Active mode when power is first applied. CURRENT MEASUREMENT AND ACCUMULATION ...
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... Average Current register have a maximum offset of ±2 LSb’s (±7.8125mV). CURRENT ACCUMULATION The DS2756 measures current for coulomb counting purposes, with an accuracy of ±2% (±3.9mV) over a range of ±64mV. Using a 20mW sense resistor, current accumulation is performed over a range of ±3.2A while measuring standby currents with an accuracy of ± ...
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ACR register address. A write to the ACR results in an automatic copy of the new value to EEPROM. Figure 5. Accumulated Current Register Format MSB-Address 10h MSb V - ...
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... Figure 6. Accumulation Bias Register Format VOLTAGE MEASUREMENT The voltage register operates in two modes, normal and snapshot. In normal mode, the DS2756 continually measures the voltage between pins V two’s-complement format every 3.4ms with a resolution of 4.88mV. In snapshot mode, the Voltage register holds the voltage measured immediately following the snapshot trigger. ...
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... Consult the Absolute Maximum Ratings table when operating the PIO pin significantly above VDD. The DS2756 turns off the PIO output driver and sets the PIO bit high when in Sleep mode or when DQ is low for more than t , regardless of the state of the PMOD bit ...
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... Suspend Threshold register is always a positive value. The Discharge Suspend Threshold register is always a negative value. The thresholds define an inclusive, continuous range of currents in which the DS2756 enters or re-enters Suspend mode from Active mode. The Charge Suspend Threshold represents the minimum measured charge current which will cause the DS2756 to transition modes ...
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... Alarm interrupt threshold values can be programmed by the user in the designated SRAM memory registers in the formats and locations found in Figure 11. Since these thresholds are located in SRAM memory, they must be reprogrammed if a loss of power to the DS2756 occurs. The DS2756 generates an alarm interrupt to indicate that one of the following events has occurred: § ...
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Figure 11. Alarm Interrupt Threshold Register Formats Current Accumulator Interrupt High Threshold MSB-Address 80h MSb Current Accumulator Interrupt Low Threshold MSB-Address 82h MSb Temperature Interrupt High ...
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... PIO Interrupts are cleared by resetting the PIO bit in the Special Feature Register . Note 3. SUSPEND state shown in this timing diagram refers to the DS2756 cycling between Active and Suspend mode at a rate determined by the PIE bit settings . Suspend state is entered by setting PIE bits to a non -zero value, setting PMOD=1, and then driving DQ low for longer than 2s ...
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SNAPSHOT MODE Measurement of the current and voltage can be synchronized to a system event with the Snapshot mode. Triggering a Snapshot event causes the ADC to abandon the current conversion and capture one current and one voltage sample. The ...
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... MEMORY The DS2756 has a 256-byte linear address space with registers for instrumentation, status, and control in the lower 32 bytes, with lockable EEPROM and SRAM memory occupying portions of the remaining address space. All EEPROM and SRAM memory is general-purpose except addresses 31h, 33h, 34h and 35h, which should be written with the default values for the Status Register, Accumulation Bias Register, Charge Suspend Threshold and Discharge Suspend Threshold, respectively ...
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... PIE1 PIE0 PIE1, PIE0—Programmable Suspend Interrupt Enable. A non zero value in these bits enables the DS2756 to enter Suspend mode, and sets the Suspend Period (t DS2756 from entering Suspend mode and allows the DS2756 to enter Sleep mode. DESCRIPTION Address 01h ...
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... This bit is read-only. The desired default value should be set in bit 4 of address 31h. The factory default is 0. UVEN—Undervoltage Sleep Enable. A value UVEN along with a value PMOD enables the DS2756 to enter Sleep mode when the voltage disables the DS2756 from entering the Sleep mode due to undervoltage events ...
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... POR PIO POR—POR Indicator bit. This bit is set when the DS2756 experiences a power-on-reset (POR) event. To use the POR bit to detect a power-on-reset, the POR bit must be set the host system upon power-up and after each subsequent occurrence of a POR. This bit is read/write to 0. ...
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... Each DS2756 has a unique, factory-programmed 1-Wire net address that is 64 bits in length. The first 8 bits are the 1-Wire family code (35h for DS2756). The next 48 bits are a unique serial number. The last 8 bits are a CRC of the first 56 bits (see Figure 18). The 64-bit net address and the 1-Wire I/O circuitry built into the device enable the DS2756 to communicate through the 1-Wire protocol detailed in the 1-Wire Bus System section of this data sheet ...
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... Figure 21 presents a transaction flowchart of the net address commands. Read Net Address [33h or 39h]. This command allows the bus master to read the DS2756’s 1-Wire net address. This command can only be used if there is a single slave on the bus. If more than one slave is present, a data collision occurs when all slaves try to transmit at the same time (open drain produces a wired-AND result) ...
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... The Read Data command can be terminated by the bus master with a reset pulse at any bit boundary. Write Data [6Ch, XX]. This command writes data to the DS2756 starting at memory address XX. The LSb of the data to be stored at address XX can be written immediately after the MSb of the address has been entered. ...
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Table 4. FUNCTION COMMANDS COMMAND DESCRIPTION Reads data from memory Read Data starting at address XX Writes data to memory Write Data starting at address XX Copies shadow RAM data to Copy Data EEPROM block containing address XX Recalls EEPROM ...
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... F0h MATCH SEARCH YES YES DS2756 Tx BIT 0 MASTER Tx BIT 0 DS2756 Tx BIT 0 MASTER Tx BIT BIT 0 BIT 0 MATCH? MATCH? YES DS2756 Tx BIT 1 MASTER Tx BIT 1 DS2756 Tx BIT 1 MASTER Tx BIT BIT 1 BIT 1 MATCH? MATCH? YES YES DS2756 Tx BIT 63 MASTER Tx BIT 63 DS2756 Tx BIT 63 MASTER Tx BIT 63 ...
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... Overdrive mode. If the line is high when sampled by the DS2756, a write 1 occurs, that is, the DS2756 accepts the bit value the line is low when sampled, a write 0 occurs, that is, the DS2756 accepts the bit value See Figure 23 for more information. ...
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... For the latest package outline information www.maxim-ic.com/DallasPackInfo.) t SLOT t LOW0 t REC TYP MAX >1ms 30ms 3ms t SLOT >1ms WRITE 1 SLOT t SLOT t LOW1 DS2755 Sample Window MIN TYP 15ms 15ms 30ms 2ms 1ms 3ms READ 1 SLOT t SLOT t REC t RDV DS2756 ACTIVE LOW RESISTOR PULLUP MAX ...