Linear Technology DC1721B-B Demo Manual

DESCRIPTION
Demonstration circuit 1721B is a 14.6V, 5A battery charger
and PowerPath™ manager with 6V
converter featuring the LTC4000/LTC3789, targeted at
4-cell LiFePO applications. The output of this demo board
4
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
PERFORMANCE SUMMARY
SYMBOL PARAMETER
V Input Supply Range
IN
1
V Input Regulation Voltage
IN-MP
2
I Input Current Limit
IN
V Battery Float Voltage
FLOAT
Output Regulation
I Battery Charge Current
BAT
V System Output Voltage
OUT-SYS
I System Output Current Range
OUT-SYS
F Switching (Clock) Frequency
SW
V System Output Ripple
OUT-SYS P-P
P /P System Output Efficiency (See Figure 3) V
OUT IN
Approximate Size
1
DC1721B-B (LTC4000-1) Only,
2
DC1721B-A (LTC4000) Only
Arrow.com.
Downloaded from
LTC4000EGN(-1)/LTC3789EGN
14.6V, 5A Battery Charger with
6V to 36V
IN
to 36V buck-boost
IN IN
Specifications are at T
CONDITIONS
This Is the Input Voltage Lower Limit Set by the LTC4000-1
Line and Load (6V to 36V, 0A to 5A)
V = 24V, I = 5A (20MHz BW)
IN OUT-SYS
= 24V, I = 5A
IN OUT-SYS
Component Area × Top Component Height
DEMO MANUAL
DC1721B-A/DC1721B-B
Buck-Boost Converter
IN
wide variety of portable applications including instruments,
industrial equipment, power tools, and computers. It has
a total footprint area of 12.4cm
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
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.
= 25°C
A
2 2
(3.6cm for the LTC4000
MIN TYP MAX UNITS
6 36 V
11.85 V
11 A
14.4 14.6 14.8 V
±0.05 %
5.0 A
12.3 14.6 15.5 V
0 6.25 A
400 kHz
50 mV
P-P
96.5 %
× 0.40cm
2
12.4cm
dc1721bf
1