1
Introduction
1.1
Description
User's Guide
SLUU261 September 2006
bq24081EVM 1-A Single-Chip Li-Ion and Li-Pol Charge
Management IC Evaluation Module
This user's guide describes the bq24081 evaluation module. The EVM provides a
convenient method for evaluating the performance of a charge management solution
for portable applications
Contents
1
Introduction
..........................................................................................
1
2
Test Summary
......................................................................................
2
3
Schematic
...........................................................................................
5
4
Physical Layouts
....................................................................................
6
5
List of Materials
.....................................................................................
8
List of Figures
1
bq24081EVM Testing Setup
......................................................................
3
2
bq24081 EVM Schematic
..........................................................................
5
3
bq24081 EVM Top Layer
........................................................................
6
4
bq24081 EVM Bottom Layer
....................................................................
6
5
bq24081 EVM Component Placement
........................................................
7
6
bq24081 Silkscreen Layer
.........................................................................
7
List of Tables
1
I/O and Jumper Connections
......................................................................
2
2
Ordering Information
...............................................................................
4
3
bq24081 EVM Parts List
...........................................................................
8
A complete designed and tested charger is presented. The charger is designed to deliver up to 1 A of
continuous charge current for singlecell Li-Ion or Li-Pol applications using a dc power supply. The
charger is programmed from the factory to deliver 0.7 A of charging current.
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1.2
Background
1.3
Performance Specification Summary
2
Test Summary
2.1
Test Setup
2.2
Test Procedure
P
= (V
- V
)
MAX
(DC+)
(BAT+)
(CHG)
x I
(1)
Test Summary
The bq24081 is a highly integrated and flexible Li-Ion linear charge device targeted at space-limited
charger applications. It offers an integrated power FET and current sensor, high-accuracy current and
voltage regulation, charge status, and charge termination, in a single monolithic device. An external
resistor sets the magnitude of the charge current.
The bq24081 charges the battery in three phases: conditioning, constant current, and constant voltage.
Charge is terminated based on minimum current. An internal charge timer provides a backup safety for
charge termination. The bq24081 automatically restarts the charge if the battery voltage falls below an
internal threshold. The bq24081 automatically enters sleep mode when the input supply is removed.
SPECIFICATION
TEST CONDITIONS
MIN
TYP
MAX
UNIT
V
I(DC)
Supply voltage range
V
(REG)
+ 0.5
5
5.5
V
I
O(CHG)
Battery charge current
(1)
0.7
1
A
Power dissipation
I
(CHG)
x (V
(DC+)
- V
(BAT+)
)
1.5
W
(1)
This input voltage maximum is a function of the maximum allowable power dissipation on the device. The current level is
programmed for 0.7 A. If the programmed charge is changed, then the maximum input voltage needs to be adjusted.
P
MAX(IC)
= 1.5 W = I
(CHG)
(V
(DC+)
V
(BAT+)
). The device has a maximum recommended operation of 6.5 Vdc.
This section shows the test setups used, and the tests performed, in evaluating the EVM. See the
bq24081 datasheet (
SLUS687
) for complete details on operation and specifications for the charger device.
The bq24081 EVM board requires a regulated 5-Vdc, 1-A power source, to provide input power and a
single-cell Li-Ion or Li-Pol battery pack.
The test setup connections and jumper setting selections are configured for a stand-alone evaluation but
can be changed to interface with external hardware such as a microcontroller.
Table 1. I/O and Jumper Connections
(1)
Jack
CONNECTION
J1DC+
Power supply positive connection, preset to 5.0-VDC, 1.2-A current limit.
J1DC-
Power supply return connection, ground
J2BAT+
Positive battery pack terminal
J2BAT-
Negative battery pack terminal, BAT, is common with DC
No connection R4 is set to 10 k
to bias the TS signal in a charging state (bq24081). See datasheet
J2TS
(
SLUS687
) to activate TS for bq24081. Connector provides for optional external control.
J2BAT-
Return for thermistor (when used)
JMP1STAT1
Monitor JMP1-2 for STAT1, or apply a shunt across JMP1 for LED status.
JMP2STAT2
Monitor JMP2-2 for STAT2, or apply a shunt across JMP2 for LED status.
JMP3TE
No jumper => Termination Enabled. Place a shunt on JMP3 to disable termination.
(1)
Factory jumper selections are shown in BOLD.
Setup the evaluation board as described above, by making the necessary I/O connections and jumper
selections. Prior to test and evaluation, it is important to verify that the maximum power dissipation on the
device is not exceeded: P
MAX
= 1.5 W.
2
bq24081EVM 1-A Single-Chip Li-Ion and Li-Pol Charge
SLUU261 September 2006
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0.7 A
70 m A
10
10
I
O(CHG)
=
=
(2)
2.3
Alternative Test Procedure
2.3.1
Equipment
R1
2 kW
0.25 W
DC+
BAT+
BAT-
+
-
DC-
BAT+
BAT-
DMM1
+
DMM2
S3
S1
S2
C1
1000 F
m
R8
0.1 W
R9
680 W
0.25 W
R2
120 W
0.25 W
R3
120 W
0.25 W
R4
120 W
0.25 W
R5
10 W
2 W
R6
10 W
2 W
R7
2.4 W
2 W
Power Supply
5.1 0.1 V
I
1.0 0.1 A
LIM
bq24081EVM
1
2
3
A
Settings for Switch S2
1. ON (Fast Charger for USB 0.5 A)
2. OFF
3. ON (Fast Charger for Adaptive Source)
A
Test Summary
1. Turn on the power supply, which is preset to 5 Vdc, and 1 A for the current limit setting.
2. The bq24081 enters preconditioning mode if the battery is below the V
(LOWV)
threshold. In this mode,
the bq24081 precharges the battery with a low current, typically:
until the battery voltage reaches the V
(LOWV)
threshold or until the precharge timer expires. If the timer
expires, then the charge current is terminated and the bq24081 enters fault mode. Both LEDs turn off
when in fault mode. Toggling input power or battery replacement resets fault mode. Note that there are
several fault conditions. They are described in the data sheet (
SLUS687
).
3. Once the battery voltage is above the V
(LOWV)
threshold, the battery enters fast charge mode. This
EVM is programmed for 0.7 A of fast charging current.
4. Once the battery reaches voltage regulation (4.2 V) the current tapers down as the battery reaches its
full capacity.
5. When the current reaches the termination threshold, the charge is terminated.
6. After termination, if the battery discharges down to the recharge threshold, the charger starts fast
charging.
An alternative method of testing the EVM is with a source meter, that can sink or source current. This can
be adjusted to test each mode, in place of a battery.
Another alternative to briefly view each mode, on a scope, is to connect a 1-mF or larger capacitor and a
parallel 10-k
resistor on the output in place of a battery to observe the charging cycling.
The procedure in
Section 2.3.1
describes a quick test to verify charging states without the need for a
battery or expensive test equipment.
1. Power source: current limited 5-V lab supply with its current limit set to 1 A
0.1 A.
2. Two fluke 75, equivalent or better.
3. Load test board as shown in
Figure 1
.
Note: R5, R6, and R7--5% or better. All other resistors--1% or better
Figure 1. bq24081EVM Testing Setup
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2.3.2
Equipment Setup
2.3.3
Procedure
2.4
Ordering Information
Test Summary
1. Connect the load board to the BAT+ and BAT. Set switches SW1 and SW3 to closed and switch SW2
to off (center).
2. Connect a voltage meter, DMM1, to the BAT+/BAT output to monitor the output voltage (range is 0 V
to 5 V).
3. Set the lab supply for 5.1 V
0.1 Vdc, 1 A
0.1 A current limit and then turn off supply. Connect DMM2
across R8 to monitor the current (R8 should be a 1% or better resistor if it is used for current
measurements).
4. Shunt jumpers should be installed on JPM1 and JPM2.
1. Make sure the steps described in
Section 2.3.2
Equipment Setup are followed (SW1 and SW3 are set
to closed, and SW2 is set to off, shunts installed as shown in step 4, test board connected, and power
source set to 5.1 V
0.1 Vdc). Turn on the power source.
2. Verify output voltage, BAT+, is between 2.5 Vdc and 2.9 Vdc and the red LED (D1) and green LEDs
(D2) are illuminated.
3. Momentarily short J52 to J11 (TS to DC+), and verify that charging stops (DMM2 < 0.5 mV).
Remove short and verify output voltage, BAT+, is between 2.5 Vdc and 2.9 Vdc.
4. Open switch SW1. Verify LED (D2) is off and the output voltage, BAT+, regulates between 4.16 Vdc
and 4.24 Vdc.
5. Close switch SW2 (to position 1) and verify output voltage, BAT+, is between 3.4 Vdc and 3.8 Vdc.
6. Verify that the charging current is between 0.6 A and 0.8 A (DMM2 is between 60 mVdc and
80 mVdc).
7. Open switch SW3, set switch SW2 to off and verify that the LEDs, (D1, D2), alternate being
illuminated.
8. Turn off power. Remove UUT from test apparatus. Repeat setup and test procedures for other
untested EVMs.
Table 2. Ordering Information
EVM Part Number
Additional Devices
Chemistry
Pack Voltage
Capacity
bq24081EVM
None
Li-Ion/Li-Poly
2.5 V to 4.2 V
Any
4
bq24081EVM 1-A Single-Chip Li-Ion and Li-Pol Charge
SLUU261 September 2006
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3
Schematic
Schematic
Figure 2
shows the schematic diagram for the bq24081EVM.
Figure 2. bq24081 EVM Schematic
SLUU261 September 2006
bq24081EVM 1-A Single-Chip Li-Ion and Li-Pol Charge
5
Management IC Evaluation Module
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