DS2786B Maxim Integrated Products, DS2786B Datasheet
DS2786B
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DS2786B Summary of contents
Page 1
... Remaining capacity is reported in percent, along with cell voltage, current, and temperature information. Cell characteristics and application parameters used in the calculations are stored in on-chip EEPROM. The DS2786B is intended for use on the host side of portable devices, though it can also be mounted within a battery pack. Measurement and estimated capacity data 2 are accessed through interface ...
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Stand-Alone OCV-Based Fuel Gauge ABSOLUTE MAXIMUM RATINGS Voltage on All Pins Except V Relative to V PROG Voltage on V Relative to V ..........................-0.3V to +18V PROG SS Operating Temperature Range ...........................-40°C to +85°C Stresses beyond those listed under “Absolute ...
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... Note 2: Offset specified after autocalibration cycle and Current Offset Bias Register = 00h. Note 3: The DS2786B enters the sleep mode 1.5s to 2.2s after (SCL < V Note 4: Timing must be fast enough to prevent the DS2786B from entering sleep mode due to bus low for period > t Note 5: f must meet the minimum clock low time plus the rise/fall times ...
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Stand-Alone OCV-Based Fuel Gauge ELECTRICAL CHARACTERISTICS: 2-WIRE INTERFACE (continued) (2.5V ≤ V ≤ 4.5V -20°C to +70°C Note 6: The maximum t has only to be met if the device does not stretch the low period ...
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... Power-Supply Input. 2.5V to 4.5V Input Range. Connect to system power through a decoupling network. — EP Exposed Pad. Connect to V _______________________________________________________________________________________ AIN1 AIN0 SCL OUT DS2786B SDA PROG EP SNS TDFN (3mm x 3mm) FUNCTION during normal operation www.DataSheet4U.com Pin Configuration Pin Description 5 ...
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... The on-chip temperature measure- ment is optional and replaces auxiliary voltage channel AIN1. Figure 1 is the 2-wire bus timing diagram; Figure 2 is the DS2786B block diagram. Figure appli- cation example. SWITCH IS ON WHEN AIN0 OR AIN1 IS BEING MEASURED. BIAS ...
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... Sleep when: SMOD = 1 and (SCL < V Caution: If SMOD = 1, a pullup resistor is required on SCL and SDA in order to ensure that the DS2786B tran- sitions from Sleep to Active Mode when the battery is charged. If the bus is not pulled up, the DS2786B remains in Sleep and cannot accumulate the charge current ...
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... Stand-Alone OCV-Based Fuel Gauge Parameter Measurement The DS2786B uses a sigma-delta A/D converter to make measurements. The measurement sequence shown in Figure 4 repeats continuously while the DS2786B is in Active Mode. The V t before the AIN0 and AIN1 conversion to allow for PRE V PIN IN AVERAGE OVER 440ms ...
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... OCV algorithm automatically adjusts for the effects of input with respect IN the offset-correction cycle. Auxilary Input Measurements The DS2786B has two auxiliary voltage-measurement inputs, AIN0 and AIN1. Both are measured with respect These inputs are designed for measuring resis- SS tor ratios, particularly useful for measuring thermistor or pack identification resistors ...
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... Status/Configuration Register must be set to enable the internal temperature measurement instead of the AIN1 measurement. Current Measurement In the Active Mode of operation, the DS2786B continu- ally measures the current flow into and out of the bat- tery by measuring the voltage drop across a low-value current-sense resistor, R ...
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... During periods of charging or discharging the cell, the DS2786B counts charge flow into and out of the cell. When the application becomes inactive, the DS2786B waits for the cell voltage to relax and then adjusts the coulomb count based on an open-circuit voltage cell model stored in device EEPROM. The resulting calculation is reported to the system as a per- centage value between 0 and 100% ...
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... See Figure 13 for the OCV thresh- old register format. While the measured current is below the OCV threshold level, the DS2786B actively searches for a relaxed cell by calculating the change in cell voltage as reported in the Voltage Register over 7.5min intervals (dV/dt). If the 7 ...
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... BREAKPOINT 8 4.171V 100% BREAKPOINT 6 4.042V 85% 100% 80% Figure 15. DS2786BG-C3 OCV Cell Model 2 MSB Figure 16. Capacity 1 to Capacity 7 Registers Format ______________________________________________________________________________________ Capacity values must be monotonic (Capacity 1 > Capacity 0, Capacity 2 > Capacity 1, etc.), but other- wise can be written to any value between 0.5% to 99.5%. Capacity 8 is fixed at a value of 100% and can- not be changed ...
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... As the cell ages, the Initial Capacity Scaling Factor Register value might no longer accurately reflect the true capacity of the cell, causing error in relative capaci- ty calculation while in coulomb-counting mode of opera- tion. The DS2786B has a learn feature that allows the IC to remain accurate as the cell changes. The DS2786B MSB—ADDRESS 14h 11 ...
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... Figure 20 shows the learn delta percent threshold. The DS2786B has memory space with registers for instru- mentation, status, and control. When the MSB of a 2-byte register is read, both the MSB and LSB are latched and ...
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Stand-Alone OCV-Based Fuel Gauge Table 3. Memory Map ADDRESS DESCRIPTION 00h Reserved 01h Status/Config Register 02h Relative Capacity 03h to 07h Reserved 08h Auxiliary Input 0 MSB 09h Auxiliary Input 0 LSB Auxiliary Input 1/ 0Ah Temperature MSB Auxiliary Input ...
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Stand-Alone OCV-Based Fuel Gauge Status/Config Register The Status/Config Register is read/write with individual bits designated as read only. Bit values indicate status as well as program or select device functionality. Bits 3 though 6 are EEPROM backed at memory location ...
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... The 2-wire interface consists of a serial data line (SDA) and serial clock line (SCL). SDA and SCL provide bidirectional communication between the DS2786B slave device and a master device at speeds up to 400kHz. The DS2786B’s SDA pin operates bidi- rectionally; that is, when the DS2786B receives data, ...
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... Acknowledge bit—master N No acknowledge—master ______________________________________________________________________________________ Slave Address The DS2786B is compatible with any bus timing up to 400kHz. No special configuration is required to operate at any speed. The command protocols involve several transaction for- mats. The simplest format consists of the master writing the START bit, slave address, and R/W bit, and then monitoring the Acknowledge bit for presence of the DS2786B ...
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... The MSB of the data to be stored at address MAddr can be written immediately after the MAddr byte is acknowledged. Because the address is automatically incremented after the LSB of each byte is received by the DS2786B, the MSB of the data at address MAddr + 20 ______________________________________________________________________________________ 1 can be written immediately after the acknowledgment of the data at address MAddr ...
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... Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 21 © 2010 Maxim Integrated Products ...