General Description
The Evaluation Board demonstrates the RT9426AWSC to provide fuel gauging for single-cell battery packs. The RT9426AWSC reports StateOfCharge, StateOfHealth, FullChargeCapacity, TimeToEmpty and CycleCount. The RT9426AWSC also provides complete battery status monitor with interrupt alarm function. It could alert to host processor actively when condition of battery over/undervoltage, under SOC, SOC change, battery presence status change and over-temperature in charge/discharge.
Performance Spcification Summary
Summary of the RT9426AWSC Evaluation Board performance specificiaiton is provided in Table 1. The ambient temperature is 25°C.
Table 1. RT9426AWSC Evaluation Board Performance Specification Summary
|
Specification
|
Test Conditions
|
Min
|
Typ
|
Max
|
Unit
|
|
Operation Voltage
|
VBAT - VSS
|
2.5
|
--
|
5.5
|
V
|
|
Active Current
|
Active mode, VDD = 3.8V,
BD_PRES_EN = 0 and not including external temp. measurement current.
|
--
|
14
|
20
|
µA
|
|
Sleep Current
|
Sleep mode, VDD = 3.8V,
BD_PRES_EN = 0 and not including external temp. measurement current.
|
--
|
5
|
7
|
µA
|
|
Shutdown Current
|
VBAT = 3.8V
|
--
|
--
|
1
|
µA
|
|
Voltage Measurement Range
|
|
2.5
|
--
|
VBAT
|
V
|
|
Voltage Measurement Error
|
VBATS = 4V, VBATG = 0V
|
-7.5
|
--
|
7.5
|
mV
|
|
Current Measurement Range
|
VCSP - VCSN
|
-125
|
--
|
125
|
mV
|
|
Current Measurement Gain Error
|
|VCSP - VCSN| = 20mV
|
-1
|
--
|
1
|
%
|
|
Current Measurement Offset Error
|
|VCSP - VCSN| = 0V (Note1)
|
-10
|
±5
|
10
|
µV
|
|
Temperature Measurement Error
|
TA = 25°C (Note 2)
|
-3
|
--
|
3
|
°C
|
|
Internal Temperature Measurement Range
|
|
-40
|
--
|
85
|
°C
|
|
Internal Temperature
Measurement Error
|
TA = 25°C
|
--
|
±3
|
--
|
°C
|
Note 1. Typical result is long time average.
Note 2. The thermistor is use 10k NTC and beta 3435k, default is SEMITEC 103KT1608T.
Power-up Procedure
Suggestion Required Equipments
- RT9426AWSC Evaluation Board
- DC power supply capable of 6V and 5A
- 1-Series (1sXp) Li-Ion/Li-Polymer Battery Cell
- Electronic load capable of 5A
- I2C communication Host
Proper measurement equipment setup and follow the procedure below.
The Evaluation Board is fully assembled and tested. Follow the steps below to verify board operation.
1) Insert battery to battery connector between B+ and B-
2) For discharge, connect electronic load from P+ to P-, adjust the discharge current according to battery spec.
3) For charge, connect DC power supply from P+ to P-, adjust the CV/CC according to battery spec.
4) Get the information like StateOfCharge, StateOfHealth, FullChargeCapacity, TimeToEmpty, CycleCount, Voltage, Current and Temperature by I2C interface.
Note: Contact with RICHTEK for detatiled battery characterizing to get custom parameter for high accuracy StateOfCharge (SOC)report.
Detailed Description of Hardware
Headers Description and Placement
Carefully inspect all the components used in the EVB according to the following Bill of Materials table, and then make sure all the components are undamaged and correctly installed. If there is any missing or damaged component, which may occur during transportation, please contact our distributors or e-mail us at evb_service@richtek.com.
Test Points
The EVB is provided with the test points and pin names listed in the table below.
|
Test Point/
Pin Name
|
Function
|
|
VBAT
|
Power supply input and battery voltage sensing input for WL-CSP package.
|
|
VPTS
|
Power reference output pin for temperature measurement
|
|
VSS
|
Device ground
|
|
CSP
|
Battery current sensing positive input. Connect a 10mΩ sense resistor with kelvin connection where is near B-side.
|
|
CSN
|
Battery current sensing negative input. Connect a 10mΩ sense resistor with kelvin connection where is near PACK- side.
|
|
TS
|
Temperature measurement input.
|
|
SDA
|
Serial data input. Slave I2C serial communications data line for communication with system. Open-drain I/O.
|
|
SCL
|
Serial clock input. Slave I2C serial communications clock line for communication with system. Open-drain I/O.
|
|
ALERT
|
Alert open-drain indicator output.
|
|
J1
|
Battery Connector.
|
|
J2
|
Load/Charger Connector.
|
|
J3
|
I2C communication interface.
|
|
J4
|
Alert pull-high enable.
|
Bill of Materials
|
Reference
|
Count
|
Part Number
|
Value
|
Description
|
Package
|
Manufacturer
|
|
U1
|
1
|
RT9426AWSC
|
RT9426AWSC
|
Single-Cell
Fuel Gauge
|
WL-CSP-9B 2.29x1.74 (BSC)
|
RICHTEK
|
|
C1
|
1
|
0603X105K250CT
|
1µF
|
Capacitor, Ceramic, 25V, X5R
|
0603
|
WALSIN
|
|
C2
|
1
|
0603B103K500CT
|
10nF
|
Capacitor, Ceramic, 50V, X7R
|
0603
|
WALSIN
|
|
C3, C4, C5
|
3
|
0603B104K250CT
|
0.1µF
|
Capacitor, Ceramic, 25V, X7R
|
0603
|
WALSIN
|
|
C6, C7
|
2
|
|
|
NC
|
|
|
|
R1
|
1
|
WR06X1002FTL
|
10k
|
Resistor, Chip, 1/10W, 1%
|
0603
|
WALSIN
|
|
R2
|
1
|
103KT1608T
|
10k
|
NTC Resistor, Chip, 3435K, 1%
|
0603
|
SEMITEC
|
|
R3, R4, R8, R9, R10, R11, R12, R13
|
8
|
WR06X1000FTL
|
100
|
Resistor, Chip, 1/10W, 1%
|
0603
|
WALSIN
|
|
R7
|
1
|
RTT034701FTP
|
4.7k
|
Resistor, Chip, 1/10W, 1%
|
SMB
|
RALEC
|
|
R5, R6
|
2
|
|
|
NC
|
|
|
|
RS1, RS2
|
2
|
RLM-0816-3F-R010-FNH
|
0.01
|
Current Sense Resistor, 1W, 1%
|
0603
|
Cyntec
|
|
D1, D2, D3
|
3
|
|
|
NC
|
|
|
Typical Applications
EVB Schematic Diagram
1. RT9426AWSC can support high/low-side current sensing, EVB is default low side sense setup.
- Mount RS1/R3/R4 for Low-Side Sensing.
- Mount RS2/R5/R6 for High-Side Sensing.
Measurement Result
|
Voltage ADC Error vs. Temperature
|
Current ADC Error vs. Temperature
|
|
|
|
|
Temp. Measurement Error vs. Temperature
|
SOC Accuracy*
|
|
|
|
*: Sample accuracy with custom parameter into the IC.
Evaluation Board Layout
Figure 1 and Figure 2 are RT9426AWSC Evaluation Board layout. This board size is 55mm x 40mm and is constructed on two-layer PCB with 1 oz. Cu.
Figure 1. Top View
Figure 2. Bottom View