IC U509 TAB T210 STc3115
IC U509 TAB T210 STc3115
IC U509 TAB T210 STc3115
Applications
• Mobile phones, multimedia players, digital
cameras
• Portable medical equipment
Description
The STC3115 includes the hardware functions
&63PP[PP 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
')1PP[PP high performance gas gauging in all application
conditions.
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
• Programmable low battery alarm
• Internal temperature sensor
• Battery swap detection
• Low power: 45 µA in power-saving mode, 2 µA
max. in standby mode
• Micro-sized packages:
– 1.4 x 2.0 mm 10-bump CSP package
– 2.0 x 3.0 mm DFN10 package
Contents
1 Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2 Pin assignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
5 Application information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
6 Functional description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
6.1 Battery monitoring functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
6.1.1 Operating modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
6.1.2 Battery voltage monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
6.1.3 Internal temperature monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
6.1.4 Current sensing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
6.2 STC3115 gas gauge architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
6.2.1 Coulomb counter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
6.2.2 Voltage gas gauge algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
6.2.3 Mixed mode gas gauge system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
6.3 Low battery alarm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
6.4 Power-up and battery swap detection . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
6.5 Improving accuracy of the initial OCV measurement with the advanced
functions of BATD/CD and RSTIO pins 19
6.5.1 BATD and RSTIO pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
6.6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
7 I2C interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
7.1 Read and write operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
7.2 Register map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
7.2.1 Register map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
7.2.2 Register description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
8 Package information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
9 Ordering information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
10 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
1 Block diagram
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4 Electrical characteristics
Table 4. Electrical characteristics (2.7 V < VCC < 4.5 V, -20 °C to 70 °C)
Symbol Parameter Conditions Min. Typ. Max. Units
Supply
Average value over 4 s in
power-saving voltage 45 60
ICC Operating current consumption mode
Average value over 4 s in
100
mixed mode µA
Standby mode,
ISTBY Current consumption in standby 2
inputs = 0 V
VCC < UVLOTH,
IPDN Current consumption in power-down 1
inputs = 0 V
UVLOTH Undervoltage threshold (VCC decreasing) 2.5 2.6 2.7 V
UVLOHYST Undervoltage threshold hysteresis 100 mV
POR Power-on reset threshold (VCC decreasing) 2.0 V
Current sensing
Vin_gg Input voltage range -40 +40 mV
IIN Input current for CG pin 500 nA
ADC_res AD converter granularity 5.88 µV
ADC_offset AD converter offset CG = 0 V -3 3 LSB
ADC_time AD conversion time 500 ms
Table 4. Electrical characteristics (2.7 V < VCC < 4.5 V, -20 °C to 70 °C) (continued)
Symbol Parameter Conditions Min. Typ. Max. Units
Table 5. I2C timing - VIO= 2.8 V, Tamb = -20 °C to 70 °C (unless otherwise specified)
Symbol Parameter Min. Typ. Max. Unit
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5 Application information
Optional filter
IO voltage
VCC
C1 R1
VIN Other
SCL STC3115 C2 detection
circuit
SDA Battery pack
ALM BATD/CD
R2
Rid
RSTIO
CG
GND Rcg
Optional filter
IO voltage
VCC
C1 R1
Other
VIN C2 detection
SCL STC3115 circuit
SDA Battery pack
ALM BATD/CD
R2
Rid
RSTIO
CG
GND
1. This track is a dedicated power supply track for the STC3115 system which, for voltage measurement
accuracy, is isolated from the application Vbat plane.
2. The STC3115 GND pin should be connected to the RCG only and for current measurement accuracy, it
should be isolated from the ground plane.
3. The STC3115 CG pin should be connected to the RCG first and for current measurement accuracy, it
should be isolated from the battery minus power path.
Note: For a detailed explanation of the RCG layout, please refer to the AN4324 (place and route
guidelines).
6 Functional description
0 Mixed mode, Coulomb counter is active, voltage gas gauge runs in parallel
Voltage gas gauge with power saving
1
Coulomb counter is not used. No current sensing.
In mixed mode, current is measured continuously (except for a conversion cycle every 4 s
and every 16 s seconds for measuring voltage and temperature respectively). This provides
the highest accuracy from the gas gauge.
In voltage mode with no current sensing, a voltage conversion is made every 4 s and a
temperature conversion every 16 s. This mode provides the lowest power consumption.
It is possible to switch between the two operating modes to get the best accuracy during
active periods, and to save power during standby periods while still keeping track of the
SOC information.
REG_CURRENT
register
EOC
CC SOC
CC SOC register (internal)
CG calculator
AD converter
GND
REG_CC_CNF
register
The REG_CC_CNF value depends on battery capacity and the current sense resistor. It
scales the charge integrated by the sigma delta converter into a percentage value of the
battery capacity. The default value is 395 (corresponding to a 10 mΩ sense resistor and
1957 mA.h battery capacity).
The Coulomb counter is inactive if the VMODE bit is set, this is the default state at power-
on-reset (POR) or reset (VMODE bit = 1).
Writing a value to the register REG_SOC (mixed mode SOC) forces the Coulomb counter
gas gauge algorithm to restart from this new SOC value.
REG_CC_CNF register is a 16-bit integer value and is calculated as shown in Equation 1:
Equation 1
Voltage register
VM configuration
VIN
AD OCV value
converter Voltage mode
(VM)
algorithm To SOC
management
Reference
OCV OCV adjustment registers
curve
Equation 2
Voltage mode
gas gauge
(VM) SOC REG_SOC
management register
Coulomb Alarm
counter management
(CC)
REG_VM_ADJ
register
Parameter
tracking REG_CC_ADJ
register
The combination of the CC and VM algorithms provides optimum accuracy under all
application conditions. The voltage gas gauge cancels any long-term errors and prevents
the SOC drift problem that is commonly found in Coulomb counter only solutions.
Furthermore, the results of the two algorithms are continuously compared and adjustment
factors are calculated. This enables the application to track the CC and VM algorithm
parameters for long-term accuracy, automatically compensating for battery aging,
application condition changes, and temperature effects. Five registers are dedicated to this
monitoring:
• REG_CC_ADJ and REG_VM_ADJ are continuously updated. They are signed, 16-bit,
user-adjusted registers with LSB = 1/512%.
• ACC_CC_ADJ and ACC_VM_ADJ are updated only when a method switch occurs.
They are signed, 16-bit user adjusted accumulators with LSB = 1/512%.
• RST_ACC_CC_ADJ and RST_ACC_VM_ADJ bits in the REG_MODE register are
used to clear the associated counter.
A battery swap is detected when the battery voltage drops below the undervoltage lockout
(UVLO) for more than 1 s. The STC3115 restarts when the voltage goes back above UVLO,
in the same way as for a power-up sequence.
Such filtering provides robust battery swap detection and prevents restarting in case of short
voltage drops. This feature protects the application against high surge currents at low
temperatures.
<1s >1s
VCC UVLO
POR
Short UVLO
event < 1s Long battery disconnection
No restart, events > 1s
No operation STC3115 restarts
interuption
Example: When BATD/CD is high (voltage above the 1.61 V threshold) for more than 1 s, a
battery swap is detected. The STC3115 restarts when the BATD/CD level returns below the
threshold, in the same way as for a power-up sequence.
Using the 1-s filter prevents false battery swap detection if short contact bouncing occurs at
the battery terminals due to mechanical vibrations or shocks.
VCC UVLO
POR
BATD_comp_out 1.61V
BATD_drive_high
RSTI
RST0
Voltage
measurement
Voltage
register
SOC register
BATD_drive_high
BATD/CD
+
BATD_comp_out
1.61 V -
RSTIO RSTI
RSTO
STC3115
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 signal is used to control the application system reset during the initial OCV
measurement. The RSTIO pin is a standard I/O pin with open drain output.
BATD/CD can be connected to the NTC sensor or to the identification resistor of the battery
pack. The STC3115 does not provide any biasing voltage or current for the battery
detection. An external pull-up resistor or another device has to pull the BATD/CD pin high
when the battery is removed.
6.6
7 I2C interface
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Control registers 0 to 23
REG_MODE 0 R/W Mode register
REG_CTRL 1 R/W Control and status register
REG_SOC (L-H) 2-3 R/W Gas gauge relative SOC 1/512%
Number of conversions
REG_COUNTER (L-H) 4-5 R 0x00 0x00 500 ms
(2 bytes)
Battery current value
REG_CURRENT (L-H) 6-7 R 0x00 0x00 5.88 µV
(2 bytes)
Battery voltage value
REG_VOLTAGE (L-H) 8-9 R 0x00 0x00 2.2 mV
(2 bytes)
REG_TEMPERATURE 10 R 0x00 0x00 Temperature data 1 °C
Coulomb counter adjustment
REG_CC_ADJ_HIGH 11 R 0x00 0x00
factor
1/2%
Voltage mode adjustment
REG_VM_ADJ_HIGH 12 R 0x00 0x00
factor
REG_OCV (L-H) 13-14 R/W 0x00 0x00 OCV register (2 bytes) 0.55 mV
Coulomb counter gas gauge
REG_CC_CNF (L-H) 15-16 R/W 395 395
configuration
Voltage gas gauge algorithm
REG_VM_CNF (L-H) 17-18 R/W 321 321
parameter
SOC alarm level
REG_ALARM_SOC 19 R/W 0x02 0x02 1/2%
(default = 1%)
Battery low voltage alarm
REG_ALARM_VOLTAGE 20 R/W 0xAA 0xAA 17.6 mV
level (default is 3 V)
Current threshold for the
REG_CURRENT_THRES 21 R/W 0x0A 0x0A 47.04 µV
relaxation counter
REG_RELAX_COUNT 22 R 0x78 0x78 Relaxation counter
Relaxation counter max
REG_RELAX_MAX 23 R/W 0x78 0x78
value
REG_ID 24 R 0x14 0x14 Part type ID = 14h
8 Package information
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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. The terminal A1, on the back side, is identified by a distinguishing feature - for instance, by a circular “clear
area” typically 0.2 mm in diameter depending on the die size.
Table 15. Flip Chip CSP 1.4 x 2.04 mm package mechanical data
Dimensions
9 Ordering information
STC3115IJT(1) O22
CSP-10
STC3115AIJT(2) O23
-40 °C to +85 °C Tape and reel
(1)
STC3115IQT O204
DFN10 2x3
STC3115AIQT(2) O205
1. 4.35 V max. battery option (3.8 V typ.).
2. 4.20 V max. battery option (3.7 V typ.).
Note: For a detailed explanation on versions A and non-A, please refer to the
AN4324.
10 Revision history
Updated tsu,sta symbol in Table 5: I2C timing - VIO= 2.8 V, Tamb = -20
10-Nov-2017 8
°C to 70 °C (unless otherwise specified).
15-Jan-2018 9 Inserted note in Section 9: Ordering information.
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