2
dc1362aabfa
DEMO MANUAL DC1362A-A/-B
OPERATING PRINCIPLE
Charge termination can occur when charge current de-
creases to one-tenth of the programmed maximum charge
current (C/10 termination). Alternately, termination can
be timer based through the use of an internal program-
mable charge cycle control timer. When using the timer
termination, charging continues beyond the C/10 level
to top off a battery. Charging typically terminates three
hours after initiation. When the timer-based scheme is
used, bad battery detection is also supported. A system
fault is triggered if a battery stays in precondition mode
for more than one-eighth of the total charge cycle time.
Once charging is terminated and the LT3651 is not ac-
tively charging, the IC automatically enters a low current
standby mode in which supply bias currents are reduced
to <85µA. If the battery voltage drops below 2.5% from the
full charge float voltage, the LT3651 engages an automatic
charge cycle restart. The IC also automatically restarts a
new charge cycle after a bad battery fault once the failed
battery is removed and replaced with another battery.
After charging is complete, the input bias current lines
connected to the battery are reduced to minimize battery
discharge.
The LT3651 contains provisions for a battery temperature
monitoring circuit. Battery temperature is monitored by
using an NTC thermistor located with the battery. If the
Figure 1. Efficiency and Power Loss vs V
IN
Demonstration circuit 1362A-A/1362A-B is easy to set
up to evaluate the performance of the LT3651EUHE-4.2/
LT3651EUHE-4.1.
Using short twisted pair leads for any power connections,
with all loads and power supplies off, refer to Figure 2 for
the proper measurement and equipment setup.
Follow the procedure below:
1. Jumper and power supply setting:
JP1 = RUN
PS1 = OFF
JP2 = C/10
PS2 = OFF
battery temperature moves outside the safe charging range
of 0°C to 40°C the charging cycle suspends and signals
a fault condition.
The LT3651 contains two digital open-collector outputs,
which provide charger status and signal fault conditions.
These binary coded pins signal battery charging, standby
or shutdown modes, battery temperature faults and bad
battery faults.
A precision undervoltage lockout is possible by using a
resistor divider on the shutdown pin (
SHDN
). The input
supply current is 17µA when the IC is in shutdown.
QUICK START PROCEDURE
2. Turn on PS2 and slowly increase the voltage to 2.7V while
monitoring the current into the BAT pin. If the current
is less than 5mA, turn on PS1. Increase the voltage on
PS1 to 4V while monitoring the input current. If the
current is less than 5mA, increase PS1 to 12V.
3. Verify that the battery charging current, IBAT is between
400mA and 600mA. The CHRG LED and ACPR LED
should be on and the FAULT LED should be off.
V
IN
(V)
5
EFFICIENCY (%)
POWER LOSS (W)
83
84
85
86
15
25
DC1362ab F01
82
81
80
3.2
3.6
4.0
4.4
2.8
2.4
2.0
10
20
30 32
V
BAT
= 3.9
E
FF
P
LOSS