LTM8062EVPBF LINER [Linear Technology], LTM8062EVPBF Datasheet - Page 13

• Manufacturer Part Number: LTM8062EVPBF
• Description: 32VIN, 2A ?Module Power Tracking Battery Charger
• Manufacturer: LINER [Linear Technology]

APPLICATIONS INFORMATION
voltage characteristic is slightly nonlinear. This nonlinear
characteristic follows the relation:
where T = temperature in °C. A thermistor-based network
can be used to approximate the nonlinear ideal tempera-
ture characteristic across a reasonable operating range,
as shown in Figure 6.
Status Pins
The LTM8062 reports charger status through two open-
collector outputs, the CHRG and FAULT pins. These pins
can be pulled up as high as V
The CHRG pin indicates that the charger is delivering
current at greater than a C/10 rate, or one-tenth of the
programmed charge current. The FAULT pin signals bad-
battery and NTC faults. These pins are binary coded, as
shown in Table 3.
Table 3. Status Pin State
CHRG
High
High
Low
Low
If the battery is removed from an LTM8062 charger that is
configured for C/10 termination, a low amplitude sawtooth
waveform appears at the charger output, due to cycling
between termination and recharge events. This cycling
V
(with a 2.18V minimum)
FLOAT
FAULT
High
Low
High
Low
= 4 • 10
LTM8062
STATUS
Not Charging—Standby or Shutdown Mode
Bad-Battery Fault (Precondition Timeout/EOC Failure)
Normal Charging at C/10 or Greater
NTC Fault (Pause)
ADJ
BAT
–5
(T
198k
2
Figure 6. Thermistor-Based Temperature Compensation Network Programs V
to Closely Match Ideal Lead-Acid Float Charge Voltage for 6-Cell Charger
) – 6 • 10
196k
69k
69k
IN
, and can sink up to 10mA.
–3
LEAD-ACID
(T) + 2.375
22k
B = 3380
BATTERY
6-CELL
8062 F06a
+
results in pulsing at the CHRG output. An LED connected
to this pin will exhibit a blinking pattern, indicating to the
user that a battery is not present. The frequency of this
blinking pattern is dependent on the output capacitance.
C/10 Charge Termination
The LTM8062 supports a low current based termination
scheme, where a battery charge cycle terminates when
the charge current falls below one-tenth the programmed
charge current, or approximately 200mA. This termination
mode is engaged by shorting the TMR pin to ground. When
C/10 termination is used, an LTM8062 charger sources
battery charge current as long as the average current level
remains above the C/10 threshold. As the full-charge float
voltage is achieved, the charge current falls until the C/10
threshold is reached, at which time the charger terminates
and the LTM8062 enters standby mode. The CHRG status
pin follows the charger cycle and is high impedance when
the charger is not actively charging. There is no provision
for bad-battery detection if C/10 termination is used.
Timer Charge Termination
The LTM8062 supports a timer-based termination scheme,
where a battery charge cycle terminates after a specific
amount of time elapses. Timer termination is engaged
when a capacitor (C
to ground. The timer cycle time span (t
by C
C
TIMER
TIMER
14.8
14.6
14.4
14.2
14.0
13.8
13.6
13.4
13.2
13.0
12.8
= t
in the equation:
–10
EOC
PROGRAMMED V
• 2.27 • 10
0
TIMER
10
TEMPERATURE (°C)
) is connected from the TMR pin
20
BAT(FLOAT)
THEORETICAL V
–7
FLOAT
30
(Hours)
40
FLOAT
50
EOC
8062 F06b
LTM8062
) is determined
60
13
8062f