DC1496B-D Datasheet DC1496B-D | P1-P3

dc1496fa

DEMO MANUAL DC1496B

DESCRIPTION

LTC2941/LTC2942:

Battery Gas Gauge with I

Interface and 14-Bit ADC

Demonstration circuit 1496B-A (Figure 1) features the

LT C

2941. Demonstration circuit 1496B-B features the

LTC2942. Demonstration circuit 1496B-C features the

LTC2941-1. Demonstration circuit 1496B-D features the

LTC2942-1. The C, D options have parts that use an internal

sense resistor while the A, B options rely on an external

precision sense resistor. All four devices measure battery

charge state in handheld PC and portable product applica-

tions. The operating range is perfectly suited for single

cell Li-Ion batteries. A precision analog coulomb counter

integrates current through a sense resistor between the

battery’s positive terminal and the load or charger. The

LTC2942 adds battery voltage and on-chip temperature

measurement with an internal 14-bit No Latency ∆Σ™

ADC. The three measured quantities (charge, voltage and

temperature) are stored in internal registers accessible via

the onboard SMBus/I

C interface.

The LTC2941/LTC2941-1 has programmable high and

low thresholds for accumulated charge. The LTC2942/

LTC2942-1 has programmable high and low thresholds for

all three measured quantities. If a programmed threshold

is exceeded, the device reports an alert using either the

L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and

No Latency ∆Σ is a trademark of Linear Technology Corporation. All other trademarks are

the property of their respective owners.

SMBus alert protocol or by setting a ﬂ ag in the internal

status register.

The LTC2941 and LTC2942 require only a single low value

sense resistor to set the measured current range. The

LTC2941-1 and the LTC2942-1 have their own 50mΩ inter-

nal resistor. The default value assembled on the DC1496 is

100mΩ for a maximum current measurement of 500mA.

Both parts have a software-conﬁ gurable charge complete/

alert pin. When the pin is set for charge complete, a jumper

connects the pushbutton which simulates a logic high input

to indicate a full battery. When the pin is conﬁ gured for

alert, the same jumper is used to connect a red LED that

indicates an alert is present. A change was made between

DC1496A and DC1496B to ﬂ oat the exposed pad under

the LTC2941/LTC2942 in accordance with the data sheet

recommendations.

The DC1496B is a part of the QuikEval system for quick

evaluation with a host controller through a PC.

Design ﬁ les for this circuit board are available at

http://www.linear.com/demo.

Figure 1. DC1496B

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DEMO MANUAL DC1496B

BUS PULL-UP

VOLTAGE

TO MICROCONTROLLER

SENSE

CHARGER LOAD

TO QuikEval

BATTERY

1-CELL

Li-Ion

–

QUICK START PROCEDURE

Demonstration circuit 1496B is easy to set up to evaluate

the performance of the LTC2941/LTC2942/LTC2941-1/

LTC2942-1. Refer to Figure 2 for proper measurement

equipment setup and follow the procedure below.

1. Connect a 1-cell Li-Ion battery across V_BAT and

GND.

2. Connect a load across V_CHRG/LD and GND for battery

discharge measurement. Up to 500mA supplied from

the battery can be measured with the board default

100mΩ sense resistor or 50mΩ internal resistor. Use

SENSE

and SENSE

–

test points to read voltage across

the sense resistor.

3. Connect a 2.7V to 5.5V battery charger supply across

V_CHRG/LD and GND. Up to 500mA supplied to the

battery can be measured with the board default 100mΩ

sense resistor. Use SENSE

and SENSE

–

test points to

read voltage across the sense resistor.

4. Connect a DC590 to 14-pin connector J1 for evaluation

with QuikEval, or connect a host controller I

C bus to

the SDA, SCL and GND test turrets.

5. Set JP1 to QuikEval if a DC590 is present. Otherwise

set JP1 to Bat/Chrg for bus pull-up to the battery, or

ﬂ oat JP1 and supply a bus pull-up voltage to VP.

6. Read and write to the LTC2941/LTC2942 through I

7. Through I

C, configure the AL/CC pin. Set JP2

accordingly.

8 If AL/CC is set for charge complete, use pushbutton

switch S1 to simulate a logic high from a controller to

indicate a fully charged battery.

Figure 2. DC1496B Basic Setup

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DEMO MANUAL DC1496B

QuikEval INTERFACE

The DC1496B can be connected to a DC590 and used

with the QuikEval software. The DC590 connects to a PC

through USB. QuikEval automatically detects the demo

board and brings up the LTC2941/LTC2942 evaluation

software interface (Figure 3).

Compact and Detailed Form

When the interface is brought up, a compact form is ﬁ rst

shown with a display for the accumulated charge register

(ACR), voltage ADC and temperature ADC. To expand the

form for a more detailed display of the LTC2941/LTC2942/

LTC2941-1/LTC2942-1 registers and board conﬁ gurations,

click on Detail. To go back to the compact form, click on

Hide.

Start/Refresh

Click on Start to begin a polling routine that refreshes the

interface every 1 second. Click on Stop to halt the poll-

ing. For a single update, click on Refresh. Each refresh

scans through the internal I

C registers and updates the

respective displays.

LTC2941 and LTC2942 Display

On a refresh or poll, the software reads Status bit A[7]

to determine communication with an LTC2941, LTC2942,

LTC2941-1 or LTC2942-1. When an LTC2941 is detected,

the voltage and temperature ADC and threshold displays

are not shown. Control bits B[7:6] conﬁ gure VBAT Alert

for the LTC2941 and ADC Mode for the LTC2942.

ACR Display

The data in the ACR (registers C and D) is displayed in one

of three selected formats: Counter in coulombs, Counter

in mA • hour, battery gas gauge in mA • hour, and battery

gas gauge in charge percentage of battery. The two gas

gauge displays correspond to the battery gas gauge full

battery conﬁ guration set in the detailed form.

Voltage and Temperature ADC (LTC2942, LTC2942-1)

Data from the Voltage ADC (registers I and J) and the

Temperature ADC (registers M and N) is displayed here

in Volts and Celsius.

Figure 3. LTC2941/LTC2942 QuikEval Interface

P1-P3 P4-P6 P7-P9 P10-P10

DC1496B-D

Mfr. #:

Buy DC1496B-D

Manufacturer:

Analog Devices Inc.

Description:

Power Management IC Development Tools LTC2942-1 Demo Board Battery Gas Gauge w/ I2C (req. DC590)

Lifecycle:

New from this manufacturer.

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DC1496B-D