RT9420 Datasheet, PDF (1/14 Pages) Richtek Technology Corporation – Host-Side Single Cell Lithium Battery Gauge

®
RT9420
Host-Side Single Cell Lithium Battery Gauge
General Description
The RT9420 is a compact, host-side fuel gauge IC for
lithium-ion (Li+) battery-powered systems.
For the embedded Fuel Gauge function, the state-of-
charge (SOC) calculation is based on the battery voltage
information and the dynamic difference between battery
voltage and relaxed OCV, by using iteration to estimate
the increasing or decreasing SOC.
Voltage-based algorithm can support smoothly SOC and
does not accumulate error with time and current. That is
an advantage compared to coulomb counter which suffer
from SOC drift caused by current-sense error and battery
self-discharge. The disadvantage of voltage-based fuel
gauge, it can report incremental SOC(%), but can't report
capacity (mAh).
A quick sensing operation provides a good initial estimate
of the battery's SOC. This feature allows the IC to be
located on system side, reducing cost and supply chain
constraints on the battery. Measurement and estimated
capacity data sets are accessed through an I²C interface.
The RT9420 is available in the WDFN-8L 2x3 package.
Features
 Host-Side Fuel Gauging
 Precision Voltage Measurement ±12.5mV Accuracy
 Accurate Relative Capacity (RSOC) Calculated from
Voltaic Gauge Algorithm with Temperature
Compensation
 No Accumulation Error on Capacity Calculation
 No Battery Relearning Necessary
 No Current Sense Resistor Required
 External Alarm/Interrupt for Low Battery Alert
 I²C Compatible Interface
 Low Power Consumption
Applications
 Smartphones
 Tablet PC
 Digital Still Cameras
 Digital Video Cameras
 Handheld and Portable Applications
Simplified Application Circuit
PACK+
+
Li +
Protection
Circuit
PACK-
PMIC_VBAT
R1
RT9420
VBAT
VDD
ALERT
C1
QS
TEST
GND
SDA
SCL
PMIC_GND
IO Power
R2
R3
System
Processor
IRQ
SDA
SCL
C2
Copyright ©2014 Richtek Technology Corporation. All rights reserved.
DS9420-01 October 2014
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
1