LTM8062IV#PBF Linear Technology, LTM8062IV#PBF Datasheet - Page 13

• Manufacturer Part Number: LTM8062IV#PBF
• Description: IC, BATT CHRG, Li-Ion, Li-Polymer, 2A, LGA77
• Manufacturer: Linear Technology

Specifications of LTM8062IV#PBF

• Battery Type: Li-Ion, Li-Polymer
• Input Voltage: 32V
• Battery Charge Voltage: 14.4V
• Charge Current Max: 2A
• Battery Ic Case Style: LGA
• No. Of Pins: 77
• No. Of Series Cells: 1

Figure 5. Lead-Acid 6-Cell Float Charge Voltage vs Temperature
with a –19.8mV/°C Temperature Coefficient Using LM234 with
the Feedback Network
APPLICATIONS INFORMATION
network shown in Figure 5, with the desired temperature
coefficient (TC) and 25°C float voltage (V
specified, and using a convenient value of 2.4k for R
necessary resistor values follow the relations:
(see the Battery Float Voltage Programming section)
LTM8062
R
R
R
FB1
FB3
FB2
BAT
ADJ
= 250k – R
=
= 43k
= –R
= –2.4k • (–0.0198 • 4405) = 210k
= 250k – 210k||43k = 215k
=
215k
R
13.5 + 210k • (0.0674 / 2.4k)
14.3
14.2
14.0
13.8
13.6
13.4
13.2
13.0
12.8
12.6
V
FB3
FLOAT
–10
SET
R
210k
R
43k
• (TC • 4405)
FB1
FB2
(25°C) + R
0
FB1
R
10
2.4k
||R
TEMPERATURE (°C)
SET
3.3
210k
FB2
20
R
V
FB1
–19.8mV/°C
R
FB
30
FB1
V
V
• (0.0674 / R
+
–
LINEAR
TECHNOLOGY
LM234
40
50
8062 F05b
− 1
60
FLOAT
SET
+
6-CELL
LEAD-ACID
BATTERY
)
(25°C))
− 1
8062 F05a
SET
,
While the circuit in Figure 5 creates a linear tempera-
ture characteristic that follows a typical –3.3mV/°C per
cell lead-acid specification, the theoretical float charge
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.
Figure 6. Thermistor-Based Temperature Compensation Network
Programs V
Voltage for 6-Cell Charger
V
(with a 2.18V minimum)
FLOAT
14.8
14.6
14.4
14.2
14.0
13.8
13.6
13.4
13.2
13.0
12.8
= 4 • 10
FLOAT
LTM8062
–10
PROGRAMMED V
to Closely Match Ideal Lead-Acid Float Charge
ADJ
BAT
0
–5
(T
198k
10
TEMPERATURE (°C)
2
) – 6 • 10
20
BAT(FLOAT)
THEORETICAL V
196k
69k
69k
30
–3
40
LEAD-ACID
(T) + 2.375
BATTERY
22k
B = 3380
6-CELL
FLOAT
50
8062 F06b
LTM8062
60
8062 F06a
+
13
8062fa