1
dc1721bf
DEMO MANUAL
DC1721B-A/DC1721B-B
DESCRIPTION
LTC4000EGN(-1)/LTC3789EGN
14.6V, 5A Battery Charger with
6V
IN
to 36V
IN
Buck-Boost Converter
Demonstration circuit 1721B is a 14.6V, 5A battery charger
and PowerPath™ manager with 6V
IN
to 36V
IN
buck-boost
converter featuring the LTC4000/LTC3789, targeted at
4-cell LiFePO
4
applications. The output of this demo board
was specifically tailored for a Tenergy 10A-hour battery,
P/N 30207. Other voltages can be set by changing ROFB2
and RBFB2. The desired nominal voltage can be accurately
trimmed by using trim resistors R42 and R43. For example,
for 14.4V battery float voltage, change ROFB2 and RBFB2
to 86.6k, and add 7.5M at R42 and R43 for greater set
point accuracy.
This circuit was designed to demonstrate the high levels of
performance, efficiency, and small solution size attainable
using these ICs in a buck-boost converter battery charger,
intelligent PowerPath manager, and power supply. It oper-
ates at 400kHz and produces a regulated 5A/14.6V battery
charger output as well as a system output of up to 6.25A
from an input voltage range of 6V to 36V: suitable for a
L
, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
PowerPath is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners.
PERFORMANCE SUMMARY
wide variety of portable applications including instruments,
industrial equipment, power tools, and computers. It has
a total footprint area of 12.4cm
2
(3.6cm
2
for the LTC4000
circuit only). Synchronous rectification helps to attain
efficiency exceeding 96% at full load and nominal input.
DC1721B-A:
The LTC4000 has an input current limit/
regulation loop that prevents overloading sources with
limited output capability.
DC1721B-B:
The LTC4000-1 instead has an input voltage
regulation loop for Maximum Power Point (MPP) control.
MPP control extracts near maximum power from high
impedance sources such as solar panels, wind turbines,
or fuel cells.
Design files for this circuit board are available at
http://www.linear.com/demo
Specifications are at T
A
= 25°C
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
IN
Input Supply Range
6
36
V
V
IN-MP
1
Input Regulation Voltage
This Is the Input Voltage Lower Limit Set by the LTC4000-1
11.85
V
I
IN
2
Input Current Limit
11
A
V
FLOAT
Battery Float Voltage
14.4
14.6
14.8
V
Output Regulation
Line and Load (6V to 36V, 0A to 5A)
±0.05
%
I
BAT
Battery Charge Current
5.0
A
V
OUT-SYS
System Output Voltage
12.3
14.6
15.5
V
I
OUT-SYS
System Output Current Range
0
6.25
A
F
SW
Switching (Clock) Frequency
400
kHz
V
OUT-SYS P-P
System Output Ripple
V
IN
= 24V, I
OUT-SYS
= 5A (20MHz BW)
50
mV
P-P
P
OUT
/P
IN
System Output Efficiency (See Figure 3) V
IN
= 24V, I
OUT-SYS
= 5A
96.5
%
Approximate Size
Component Area
×
Top Component Height
12.4cm
2
×
0.40cm
1
DC1721B-B (LTC4000-1) Only,
2
DC1721B-A (LTC4000) Only
Downloaded from
