LT3652HVEDD-PBF LINER [Linear Technology], LT3652HVEDD-PBF Datasheet - Page 17

• Manufacturer Part Number: LT3652HVEDD-PBF
• Description: Power Tracking 2A Battery Charger
• Manufacturer: LINER [Linear Technology]

APPLICATIONS INFORMATION
and 25°C float voltage (V
a convenient value of 2.4k for R
values follow the relations:
R
R
R
While the circuit in Figure 9 creates a linear temperature
characteristic that follows a typical –3.3mV/°C per cell
lead-acid specification, the theoretical float charge voltage
characteristic is slightly nonlinear. This nonlinear charac-
teristic follows the relation V
– 6 × 10
T = temperature in °C. A thermistor-based network can
be used to approximate the nonlinear ideal temperature
characteristic across a reasonable operating range, as
shown in Figure 10.
FB1
FB2
FB3
= –R
= –2.4k • (–0.0198 • 4405) = 210k
= R
= 210k/({[13.5 + 210k • (0.0674/2.4k)]/3.3} – 1)
= 43k
= 250k - R
= 250k – 210k||43k = 215k (see the Battery Float
Voltage Programming section)
–3
R
FB1
SET
Figure 10. Thermistor-Based Temperature Compensation Network Programs V
Lead-Acid Float Charge Voltage for 6-Cell Charger
(T) + 2.375 (with a 2.18V minimum), where
SET
)] / V
/ ({[V
• (TC • 4405)
FB1
FB
FLOAT(25°C)
LT3652HV
||R
} – 1)
FB2
BAT
FLOAT(25°C)
V
FB
FLOAT(1-CELL)
198k
196k
+ R
69k
69k
SET
FB1
) specified, and using
, necessary resistor
• (0.0674/
22k
B = 3380
= 4 × 10
LEAD-ACID
BATTERY
6-CELL
3652 F10a
–5
+
(T
2
)
Status Pins
The LT3652HV reports charger status through two open
collector outputs, the CHRG and FAULT pins. These pins
can accept voltages as high as V
10mA when enabled.
The CHRG pin indicates that the charger is delivering
current at greater that a C/10 rate, or 1/10th of the pro-
grammed maximum charge current. The FAULT pin signals
bad battery and NTC faults. These pins are binary coded,
and signal following the table below, where ON indicates
pin pulled low, and OFF indicates pin high-impedance:
If the battery is removed from an LT3652HV charger that
is configured for C/10 termination, a sawtooth waveform
STATUS PINS STATE
CHRG
OFF
OFF
ON
ON
14.8
14.6
14.4
14.2
14.0
13.8
13.6
13.4
13.2
13.0
12.8
–10
PROGRAMMED V
FAULT
OFF
OFF
ON
ON
0
10
TEMPERATURE (°C)
FLOAT
Not Charging — Standby or Shutdown Mode
Bad Battery Fault (Precondition Timeout / EOC
Failure)
Normal Charging at C/10 or Greater
NTC Fault (Pause)
20
BAT(FLOAT)
THEORETICAL V
to Closely Match Ideal
30
40
CHARGER STATUS
FLOAT
IN
50
3652 F10b
, and can sink up to
LT3652HV
60
17
3652hvf