LTC3789 LINER [Linear Technology], LTC3789 Datasheet - Page 27

• Manufacturer Part Number: LTC3789
• Description: High Voltage High Current Controller for Battery Charging and Power Management
• Manufacturer: LINER [Linear Technology]

applicaTions inForMaTion
DESIGN EXAMPLE
In this design example, the LTC4000 is paired with the
LT3845 buck converter to create a 10A, 3-cell LiFePO
battery charger. The circuit is shown on the front page
and is repeated here in Figure 14.
• The input voltage monitor falling threshold is set at
• The IL pin is left open such that the voltage on this pin
14.3V according to the following formula:
is >1.05V. The regulation voltage on the IIMON pin is
clamped at 1.0V with an accurate internal reference.
Therefore, the input current limit is set at 10A according
to the following formula:
R
R
VM1
IS
=
=
0.050V
⎛
⎜
⎝
10A
15V TO 60V
1.193V
14.3V
= 5mΩ
− 1
1.10M
100k
⎞
⎟ • 100kΩ ≈ 1.10MΩ
⎠
5m
Figure 14. 48V to 10.8V at 10A Buck Converter Charger for Three LiFePO
10nF
3.0V
IN
1µF
SHDN
10nF
RST
CLN
IN
VM
ENC
CHRG
FLT
IIMON
IBMON
LT3845
ITH
V
TMR
C
14.7k
0.1µF
OUT
CC
IL
100µF
47nF
CL
LTC4000
4
22.1k
• R
• The trickle charge current level is consequently set at
• The battery float voltage is set at 10.8V according to
• The bad battery detection time is set at 43 minutes
CX
IID
22.1k
is 1.25V. Similar to the IIMON pin, the regulation voltage
on the IBMON pin is clamped at 1V with an accurate
internal reference. Therefore, the charge current limit
is set at 10A according to the following formula:
1.25A, according to the following formula:
the following formula:
according to the following formula:
I
I
R
C
CLIM(MAX)
CLIM(TRKL)
CL
IGATE
BFB1
TMR
GND BIAS
is set at 24.9kΩ such that the voltage at the CL pin
(nF) = t
CSP
=
Si7135DP
⎛
⎜
⎝
BGATE
1.136
10.8
CSN
OFB
FBG
NTC
BAT
BFB
1µF
=
= 0.25µA •
BADBAT
0.050V
R
− 1
CS
10k
N02N1002J
NTHS0603
⎞
⎟ • 133kΩ ≈ 1.13MΩ
⎠
(h) • 138.5 =
=
24.9kΩ
1.15M
127k
133k
0.050V
4
1.13M
5mΩ
10k
5mΩ
Cells
5m
Si7135DP
10.8V FLOAT
10A MAX CHARGE
CURRENT
4000 F14
= 1.25A
= 10A
3-CELL Li-Ion
BATTERY PACK
43
60
12V, 15A
LTC4000
• 138.5 = 100nF
27
4000f