LTM8062IV#PBF Linear Technology, LTM8062IV#PBF Datasheet - Page 16

• 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

APPLICATIONS INFORMATION
LTM8062
4. Connect all of the GND connections to as large a copper
5. For good heat sinking, use vias to connect the GND cop-
Hot-Plugging Safely
The small size, robustness and low impedance of ceramic
capacitors make them an attractive option for the input
bypass capacitor of LTM8062. However, these capacitors
can cause problems if the LTM8062 is plugged into a
live input supply (see Application Note 88 for a complete
discussion). The low loss ceramic capacitor combined
with stray inductance in series with the power source
forms an underdamped tank circuit, and the voltage at the
V
nominal input voltage, possibly exceeding the LTM8062’s
rating and damage the part. If the input supply is poorly
controlled or the user will be plugging the LTM8062 into
an energized supply, the input network should be designed
to prevent this overshoot. This can be accomplished by
installing a small resistor in series with V
popular method of controlling input voltage overshoot is
to add an electrolytic bulk capacitor to the V
capacitor’s relatively high equivalent series resistance
damps the circuit and eliminates the voltage overshoot.
The extra capacitor improves low frequency ripple filter-
ing and can slightly improve the efficiency of the circuit,
though it is physically large.
16
IN
pour or plane area as possible on the top layer. Avoid
breaking the ground connection between the external
components and the LTM8062.
per area to the board’s internal ground planes. Liberally
distribute these GND vias to provide both a good ground
connection and thermal path to the internal planes of the
printed circuit board. Pay attention to the location and
density of the thermal vias in Figure 5. The LTM8062
can benefit from the heat-sinking afforded by vias that
connect to internal GND planes at these locations, due to
their proximity to internal power handling components.
The optimum number of thermal vias depends upon
the printed circuit board design. For example, a board
might use very small via holes. It should employ more
thermal vias than a board that uses larger holes.
pin of the LTM8062 can ring to more than twice the
IN
, but the most
IN
net. This
Parallel Operation
If more current is desired, multiple LTM8062s may be
paralleled, as shown in the Typical Applications section.
When doing so, bear in mind the following:
1. Each LTM8062 ADJ pin requires 250k input resistance
2. Tie the BAT outputs directly together. Apply the same
3. The individual LTM8062s may not share current equally
Thermal Considerations
The thermal performance of the LTM8062 is given in the
Typical Performance Characteristics section. These curves
were generated by the LTM8062 mounted to a 58cm
4-layer FR4 printed circuit board. Boards of other sizes
and layer count can exhibit different thermal behavior, so
it is incumbent upon the user to verify proper operation
over the intended system’s line, load and environmental
operating conditions.
For increased accuracy and fidelity to the actual application,
many designers use FEA to predict thermal performance.
To that end, the Pin Configuration section of the data sheet
typically gives four thermal coefficients:
1. θ
2. θ
3. θ
4. θ
as described in the ADJ pin function description. Table 1
gives the recommended resistor network for a single
LTM8062. If using more than one, either apply one
network of the appropriate value to each LTM8062’s
ADJ pin or apply a single network, each resistor value
divided by the number of paralleled LTM8062s and
connect all of the ADJ pins together.
output capacitance to each LTM8062 as if it were used
as a single device and not paralleled.
as the battery nears the float voltage.
tom of the product case.
product case.
circuit board.
JA
JCbottom
JCtop
JB
: Thermal resistance from junction to ambient.
: Thermal resistance from junction to the printed
: Thermal resistance from junction to top of the
: Thermal resistance from junction to the bot-
8062fa
2