Datasheet

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This is information on a product in full production.

January 2014 DocID023755 Rev 4 1/31

STC3115

Gas gauge IC with alarm output for handheld applications

Datasheet - production data

Features

• OptimGauge

algorithm

• 0.25% accuracy battery voltage monitoring

• Coulomb counter and voltage-mode gas gauge

operations

• Robust initial open-circuit-voltage (OCV)

measurement at power up with debounce

delay

• Low battery level alarm output with

programmable thresholds

• Internal temperature sensor

• Battery swap detection

• Low power: 45 µA in power-saving mode, 2 µA

max in standby mode

• 1.4 x 2.0 mm 10-bump CSP package

Applications

• Mobile phones, multimedia players, digital

cameras

• Portable medical equipment

Description

The STC3115 includes the hardware functions

required to implement a low-cost gas gauge for

battery monitoring. The STC3115 uses current

sensing, Coulomb counting and accurate

measurements of the battery voltage to estimate

the state-of-charge (SOC) of the battery. An

internal temperature sensor simplifies

implementation of temperature compensation.

An alarm output signals a low SOC condition and

can also indicate low battery voltage. The alarm

threshold levels are programmable.

The STC3115 offers advanced features to ensure

high performance gas gauging in all application

conditions.

CSP (1.4 x 2.0 mm)

www.st.com

Summary of content (31 pages)

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STC3115 Gas gauge IC with alarm output for handheld applications Datasheet - production data Description The STC3115 includes the hardware functions required to implement a low-cost gas gauge for battery monitoring. The STC3115 uses current sensing, Coulomb counting and accurate measurements of the battery voltage to estimate the state-of-charge (SOC) of the battery. An internal temperature sensor simplifies implementation of temperature compensation.
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Contents STC3115 Contents 1 Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 Pin assignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3 Absolute maximum ratings and operating conditions . . . . . . . . . . . . . 4 4 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 5 Application information . . . . . . . . . . . . . . . . . . . . . . .
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STC3115 Contents 9 Ordering information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 10 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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Block diagram 1 STC3115 Block diagram Figure 1.
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STC3115 2 Pin assignment Pin assignment Table 1. STC3115 pin description Pin no.
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Electrical characteristics 4 STC3115 Electrical characteristics Table 4. Electrical characteristics (2.7 V < VCC < 4.
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STC3115 Electrical characteristics Table 4. Electrical characteristics (2.7 V < VCC < 4.5 V, -20 °C to 70 °C) (continued) Symbol Parameter Conditions Min Typ Max Units 4.5 V Battery voltage and temperature measurement Vin_adc Input voltage range VCC = 4.5 V LSB LSB value ADC_time AD conversion time Volt_acc 2.7 V < Vin < 4.
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Electrical characteristics STC3115 Table 5. I2C timing - VIO= 2.8 V, Tamb = -20 °C to 70 °C (unless otherwise specified) Symbol Parameter Min Typ Max Unit 400 kHz Fscl SCL clock frequency thd,sta Hold time (repeated) START condition 0.6 tlow LOW period of the SCL clock 1.3 thigh HIGH period of the SCL clock 0.6 tsu,dat Setup time for repeated START condition 0.6 thd,dat Data hold time 0 tsu,dat Data setup time 100 tr Rise time of both SDA and SCL signals 20+ 0.
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STC3115 5 Application information Application information Figure 3. Example of an application schematic using the STC3115 in mixed mode Optional filter IO voltage VCC C1 STC3115 SCL SDA R1 VIN C2 Other detection circuit Battery pack BATD/CD ALM R2 Rid RSTIO/BATD CG GND Rcg Table 6.
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Application information STC3115 Table 7.
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STC3115 Functional description 6 Functional description 6.1 Battery monitoring functions 6.1.1 Operating modes The monitoring functions include the measurement of battery voltage, current, and temperature. A Coulomb counter is available to track the SOC when the battery is charging or discharging at a high rate. A sigma-delta A/D converter is used to measure the voltage, current, and temperature. The STC3115 can operate in two different modes with different power consumption (see Table 8.
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Functional description 6.1.3 STC3115 Internal temperature monitoring The chip temperature (close to the battery temperature) is measured using one conversion cycle of the A/D converter every 16 s. The conversion cycle takes 213 = 8192 clock cycles. Using the 32768 Hz internal clock, the conversion cycle time is 250 ms. Resolution is 1° C and range is -40 to +125 °C. The result is stored in the REG_TEMPERATURE register (see Table 12). 6.1.
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STC3115 Functional description 6.2 STC3115 gas gauge architecture 6.2.1 Coulomb counter The Coulomb counter is used to track the SOC of the battery when the battery is charging or discharging at a high rate. Each current conversion result is accumulated (Coulomb counting) for the calculation of the relative SOC value based on the configuration register. The system controller can control the Coulomb counter and set and read the SOC register through the I2C control registers. Figure 5.
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Functional description 6.2.2 STC3115 Voltage gas gauge algorithm No current sensing is needed for the voltage gas gauge. An internal algorithm precisely simulates the dynamic behavior of the battery and provides an estimation of the OCV. The battery SOC is related to the OCV by means of a high-precision reference OCV curve built into the STC3115.
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STC3115 6.2.3 Functional description Mixed mode gas gauge system The STC3115 provides a mixed mode gas gauge using both a Coulomb counter (CC) and a voltage-mode (VM) algorithm to track the SOC of the battery in all conditions with optimum accuracy. The STC3115 directly provides the SOC information. The Coulomb counter is mainly used when the battery is charging or discharging at a high rate.
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Functional description 6.3 STC3115 Low battery alarm The ALM pin provides an alarm signal in case of a low battery condition. The output is an open drain and an external pull-up resistor is needed in the application. Writing the IO0DATA bit to 0 forces the ALM output low; writing the IO0DATA bit to 1 lets the ALM output reflect the battery condition. Reading the IO0DATA bit gives the state of the ALM pin.
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STC3115 6.4 Functional description Power-up and battery swap detection When the STC3115 is powered up at first battery insertion, an automatic battery voltage measurement cycle is made immediately after startup and debounce delay. This feature enables the system controller to get the SOC of a newly inserted battery based on the OCV measured just before the system actually starts. Figure 8.
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Functional description 6.5 STC3115 Improving accuracy of the initial OCV measurement with the advanced functions of BATD/CD and RSTIO/BATD pins The advanced functions of the BATD/CD and RSTIO/BATD pins provide a way to ensure that the OCV measurement at power-up is not affected by the application startup or by the charger operation.
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STC3115 Functional description Figure 11. BATD and RSTIO VCC BATD_drive_high BATD/CD + - 1.61 V RSTIO/BATD BATD_comp_out RSTI RSTO The BATD/CD pin used as a battery detector is an analog I/O.The input detection threshold is typically 1.61V. BATD/CD is also an output connected to VCC level when active. Otherwise, it is high impedance. The RSTIO/BATD signal is used to control the application system reset during the initial OCV measurement. The RSTIO/BATD pin is a standard I/O pin with open drain output.
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I2C interface STC3115 7 I2C interface 7.1 Read and write operations The I2C interface is used to control and read the current accumulator and registers. It is compatible with the Philips I2C Bus® (version 2.1). It is a slave serial interface with a serial data line (SDA) and a serial clock line (SCL). • SCL: input clock used to shift data • SDA: input/output bidirectional data transfers A filter rejects the potential spikes on the bus data line to preserve data integrity.
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I2C interface STC3115 Figure 13. Read operation 6ODYH 0DVWHU 6WDUW 'HYLFHĆDGGU ĆELWV : $ 5HJĆDGGUHVVĆ $ 5HVWDUW ĆELWV 'HYLFHĆDGGU ĆELWV 5 $ 5HJĆGDWDĆ $ ĆELWV 6WDUWĆELWĆ Ć6'$ĆIDOOLQJĆZKHQĆ6&/Ć Ć 6WRSĆELWĆ Ć6'$ĆULVLQJĆZKHQĆ6&/Ć Ć Ć 5HVWDUWĆELWĆ ĆVWDUWĆDIWHUĆDĆVWDUW $FNQRZOHGJHĆ Ć6'$ĆIRUFHGĆORZĆGXULQJĆDĆ6&/ĆFORFN 5HJĆGDWDĆ $ ĆELWV 5HJĆGDWDĆ ĆELWV $GGUHVV Q $GGUHVV Q $ 6WRS *$3060' Figure 14.
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I2C interface STC3115 7.2 Register map 7.2.1 Register map The register space provides 28 control registers, 1 read-only register for device ID, 16 read/write RAM working registers reserved for the gas gauge algorithm, and 16 OCV adjustment registers. Mapping of all registers is shown in Table 12. Detailed descriptions of registers 0 (REG_MODE) and 1 (REG_CTRL) are shown in Table 13 and Table 14.
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I2C interface STC3115 Table 12. Register map (continued) Address (decimal) Type POR Soft POR Description REG_CC_ADJ_LOW 25 R/W 0x00 0x00 Coulomb counter adjustment factor REG_VM_ADJ_LOW 26 R/W 0x00 0x00 Voltage mode adjustment factor ACC_CC_ADJ 27-28 R/W 0x00 0x00 Coulomb Counter correction accumulator ACC_VM_ADJ 29-30 R/W 0x00 0x00 Voltage mode correction accumulator RAM registers 32 to 47 Name REG_RAM0 32 R/W ... ...
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I2C interface 7.2.2 STC3115 Register description Values held in consecutive registers (such as the charge value in the REG_SOC register pair) are stored with high bits in the first register and low bits in the second register. The registers must be read with a single I2C access to ensure data integrity. It is possible to read multiple values in one I2C access. All values must be consistent. The SOC data are coded in binary format and the LSB of the low byte is 1/512 %.
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I2C interface STC3115 Table 14. REG_CTRL - address 1 Name IO0DATA Position Type Def. R X ALM pin status 0 = ALM input is low 1 = ALM input is high W 1 ALM pin output drive 0 = ALM is forced low 1 = ALM is driven by the alarm conditions 0 Description GG_RST 1 W 0 0: no effect 1: resets the conversion counter GG_RST is a self-clearing bit.
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Package information 8 STC3115 Package information In order to meet environmental requirements, ST offers these devices in different grades of ECOPACK® packages, depending on their level of environmental compliance. ECOPACK® specifications, grade definitions and product status are available at: www.st.com. ECOPACK® is an ST trademark.
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STC3115 8.1 Package information Flip Chip CSP 1.40 x 2.04 mm package information Figure 15. Flip Chip CSP 1.40 x 2.04 mm package mechanical drawing ' I' H I( $ VHH QRWH H ( ' & % $ %RWWRP YLHZ E & $ $ FFF $ * & ( ' 7RS YLHZ &63B BRSWLRQ+B9 1. The terminal A1 on the bump side is identified by a distinguishing feature - for instance, by a circular “clear area” typically 0.1 mm in diameter and/or a missing bump. 2.
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Package information STC3115 Table 15. Flip Chip CSP 1.4 x 2.04 mm package mechanical data Dimensions Ref. Millimeters Inches Min. Typ. Max. Min. Typ. Max. A 0.545 0.600 0.655 0.021 0.024 0.026 A1 0.165 0.200 0.235 0.006 0.008 0.009 A2 0.330 0.350 0.370 0.013 0.014 0.015 b 0.220 0.260 0.300 0.009 0.010 0.012 D 1.98 2.01 2.04 0.078 0.079 0.080 D1 E 1.20 1.34 E1 1.37 0.047 1.40 0.053 0.800 0.054 0.031 e 0.360 0.400 0.440 0.014 0.016 0.017 fD 0.
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STC3115 9 Ordering information Ordering information Table 16. Order code Order code Temperature range Package Packing -40 °C to +85 °C CSP-12 Tape and reel STC3115IJT(1) STC3115AIJT(2) Marking O22 O23 1. 4.35 V battery option 2. 4.
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Revision history 10 STC3115 Revision history Table 17. Document revision history Date Revision 22-Nov-2012 1 Initial release 2 Table 4: added “BATD” and “CD” Section 6.4: removed option “RSTIO/BATD” Section 6.5: added “BATD” and “CD” Section 6.5.
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STC3115 Please Read Carefully: Information in this document is provided solely in connection with ST products. STMicroelectronics NV and its subsidiaries (“ST”) reserve the right to make changes, corrections, modifications or improvements, to this document, and the products and services described herein at any time, without notice. All ST products are sold pursuant to ST’s terms and conditions of sale.