DC569A - Demo Manual

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 569
LI-ION BATTERY CHARGER IN SOT-23
LTC4054-4.2
DESCRIPTION
Demonstration circuit 569 is a single cell Li-ion linear
charger in a SOT-23. Charge rates as high as 600mA can
be achieved due to the LTC4054’s internal die temperature control loop that prevents excessive PCB heating
under worst-case conditions. The user is provided with a
control jumper to select between OFF/450mA/600mA
charge rates. The reduced charge rate is suitable for
USB applications. A charge LED illuminates while the
charger is charging the battery.
Design files for this circuit board are available. Call
the LTC factory.
Table 1. Performance Summary
PARAMETER
CONDITION
VALUE
Input Voltage
4.25–10V
IOUT
450mA selected VBAT = 3.6V
450mA ±7%
IOUT
600mA selected VBAT = 3.6V
600mA ±7%
Float voltage
VIN = 5V
4.20v ±1%
Trickle Charge threshold
VIN = 5V
2.9V ±0.1V
C/10 detection
VIN =5V VBAT = 4.2
C/9–C/11
Recharge threshold
Vin 5V
4.05V+-50mV
OPERATING PRINCIPLES
Demonstration circuit 569 is a simple single cell Li-ion
charger. The demo features the LTC4054-4.2 charger IC.
This charger implements a constant die temperature,
constant current, and constant voltage charge scheme.
Charge termination occurs when the charge rate falls to
beneath 10% of the programmed charge current. A topping charge will be applied if the cell voltage falls to
4.05V to insure long-term charge maintenance. Deeply
discharged cells are conditioned with a low C/10 trickle
current until the cell voltage reaches 2.9V whereupon
full charge current is applied. In the event that full
charge current would result in excessive dissipation a
die temperature control loop backs off the charge current to maintain a reasonable PC board temperature. A
charge LED is provided that illuminates every time the
charger is charging the battery. The peak charge current
is jumper selectable at either 600mA or 450mA. The
450mA rate is intended for USB applications.
QUICK START PROCEDURE
Demonstration circuit 569 is easy to set up to evaluate
the performance of the LTC4054-4.2. Refer to Figure 1
for proper measurement equipment setup and follow the
procedure below:
1. Use the jumper provided to select the desired charge
rate 450mA or 600mA.
2. With the power off, connect the input power supply to
Vin and GND.
3. Connect the demo board to the battery simulator as
shown in Figure 1.
4. Set the battery simulator voltage to zero, and then
slowly raise the input voltage.
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QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 569
LI-ION BATTERY CHARGER IN SOT-23
When the supply voltage exceeds 4.25V the charger
should activate and the charge LED will illuminate.
constant die temperature loop is no longer active and
the charge current is the programmed charge current.
5. Note that so long as the battery voltage is under the
9. Continue to increase the battery voltage, as the bat-
Trickle Charge threshold of 2.9V the charge current is
10% of the selected charge current.
tery voltage approaches the float voltage of 4.2V the
charge current begins to drop. Note that as the charge
current drops to 10% of the programmed current the
charger terminates. Charge current falls to zero and
the charge LED extinguishes.
6. Increase the battery voltage to about 3V and note that
the charge current has increased beyond the trickle
charge current.
7. Heat up the LTC4054 by touching a soldering iron to
the PCB.
Verify that the LTC4054-4.2 thermal loop is working—
the charge current should decrease. Remove the iron
and the charge current increases. This demonstrates
the “constant die temperature” operating mode.
8. Continue to increase the battery voltage. Note that as
10. Slowly decrease the battery voltage to simulate a long
term self-discharge of the battery. Note that as the
battery voltage drops to 4.05V that another charge
cycle is initiated.
11. Place the charge rate selector in the OFF position.
Note that the battery current draw is extremely low
(approx 1µA) also note that the supply current draw is
low (approx 20µA).
the voltage drop across the LTC4054 decreases the
MEASURE
CHARGE
CURRENT
(IBAT)
+
–
+
+
+
–
–
VBAT
–
INPUT
POWER
SUPPLY
4.25V–10V
1A
RECOMMENDED
LI-ION BATTERY SIMULATOR*
+
2Ω
10W
PRELOAD
–
BATTERY
SIMULATOR
BENCH
POWER SUPPLY
0V–4.5V
3A
WITH COURSE
AND FINE
VOLTAGE
ADJUSTMENT
* CAN USE A LI-ION BATTERY,
THOUGH TESTING TAKES MORE TIME
Figure 1. Proper Measurement Equipment Setup
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QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 569
LI-ION BATTERY CHARGER IN SOT-23
USB APPLICATIONS
USB battery chargers based on the LTC4054-4.2 can be
created in a variety of ways. One way is to place the USB
load parallel to the battery. The advantage to this scheme
is that no special measures must be taken with the load
in order to gain USB compliance. The disadvantage to
this scheme is that all USB power flows through the
LTC4054 so some of the USB power is inevitably dissipated in the LTC4054. Additional load current registers
as battery current and could potentially disrupt the C/10
termination scheme.
The preferred technique for USB charger applications is
to use the LTC4410 USB power manager IC available on
demonstration circuit 567.
The problem is that DC567 combines the LTC4410 and
the LTC4053 in a complete USB compliant charging solution. Nevertheless, it is not difficult to disconnect the
LTC4053 on DC567 and instead hook up the LTC4054
from DC569.
TESTING THE USB-COMPLIANT CHARGER
1. Hook up an adjustable load (0mA–500mA) to the USB
Device terminal of the DC567.
2. Hook up the USB input supply 5V, 500mA to the Vin
terminal of either demo board.
3. Hook up the simulated battery as previously de-
scribed or an actual battery to the battery terminal of
DC569.
4. Place the charge current jumper of DC569 in the
450mA USB Appl. position.
5. Simulate the USB low power mode by placing the
Mode jumper on DC567 in the 100mA position.
6. Turn on the input supply.
7. Set the simulated battery to some nominal voltage
typically 3.6V.
8. Set the load of the USB device to 0mA.
COMBINING DC567 AND DC569 TO CREATE A USBCOMPLIANT CHARGER
1. On DC567 separate the LTC4053 from the LTC4410 by
using an Xacto knife to cut through the four traces
connecting the two halves of the demo board.
2. Connect DC567 and DC569 together as follows.
a.
GND of DC567 to GND of DC569
b.
Vin of DC567 to Vin of DC569
c.
CHP/Monitor pin of DC567 to Prog/Monitor pin of
DC569
d.
From Battery terminal of DC567 to the Battery terminal of DC569
9. Note the charge current to the battery and the input
current.
10. Now increase the USB load current, note that the bat-
tery current decreases and the input current remains
constant and below 100mA
11. Simulate the USB high power mode by placing the
mode jumper on DC567 in the 500mA position and
repeating steps 8–10. The input current remains below 500mA
12. Simulate the USB suspend mode by setting the mode
jumper on DC567 in the 500mA position and by
removing the Charge Current jumper from DC569.
Note the input current is below 100µA.
This creates a USB compliant battery charger.
3
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 569
LI-ION BATTERY CHARGER IN SOT-23
–
–
+
+
–
INPUT POWER SUPPLY
5V, 500mA
+
MEASURE
CHARGE
CURRENT
(IBAT)
+
–
+
VBAT
RECOMMENDED
LI-ION BATTERY SIMULATOR*
+
2Ω
10W
PRELOAD
–
–
BATTERY
SIMULATOR
BENCH
POWER SUPPLY
0V–4.5V
3A
WITH COURSE
AND FINE
VOLTAGE
ADJUSTMENT
* CAN USE A LI-ION BATTERY,
THOUGH TESTING TAKES MORE TIME
CUT ALL TRACES
ALONG THIS LINE
TO SEPARATE USB
POWER MANAGER
FROM BATTERY CHARGER
–
–
+
+
–
+
LOAD
SIMULATED USB DEVICE
0mA–500mA LOAD
Figure 2. Combining DC567 and DC569 to Create a USB-Compliant Charger
4
5
4
3
2
1
D
D
C
C
1
CHRG
2
GND
3
BAT
PROG 5
VCC 4
B
B
A
A
5
4
3
2
1
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