NE57611BDH Philipss, NE57611BDH Datasheet - Page 9

• Manufacturer Part Number: NE57611BDH
• Description: Single cell Li-ion battery charger
• Manufacturer: Philipss

handling capability of the part can be increased without sacrificing its
Philips Semiconductors
This chart gives the power transistor package one can use if the
minimum recommended pad size is used under the power part. If a
larger copper pad is provided under the power device, the power
reliability. Table 1 shows how to dissipate more power in a smaller
part.
Table 1. Power handling capability
Given for F4 fiberglass PCB with 2 oz. copper
NOTE:
Going beyond five times the minimum recommended footprint yields
diminishing improvements to the thermal performance.
2003 Oct 15
Pad Size
2X
3X
4X
5X
Figure 7. Pass transistor surface mount packages using the
Single cell Li-ion battery charger
2
1
minimum recommended footprint.
25
SOT23
MAXIMUM AMBIENT TEMPERATURE ( C)
R
0.88 K/W
0.80 K/W
0.74 K/W
0.70 K/W
th(j-a)
SOT223
DPAK
50
D2PAK
Power increase (%)
14%
25%
35%
43%
75
SL01665
100
9
environmental hazards and for random component failures. Some of
Placing the overvoltage thresholds
For safety and reliability, the lithium-ion protection circuit inside the
battery pack should not be used to terminate the charging process
routinely. The protection circuit should only activate when the
charger has failed. Therefore, the full-charge termination voltage
should be set lower than the overvoltage trip threshold of the
protection circuit. To assure that the protection circuit never trips
routinely, the charger termination voltage should be set below the
sum of the two voltage accuracy tolerances of the protection circuit
and the charger. This would be about 50 – 55 mV below.
Design-related safety issues
In designing charging circuits for lithium-ion and polymer cells, the
designer should provide for user mishandling, common
the user-related issues are plugging the battery pack into the
charger backwards, live insertion of the battery into the charger and
the charger into the input voltage source. A reverse biased diode is
typically provided for the reversed battery. This shunts the reverse
currents away from the IC thus protecting the functionality of the
charger. To protect against live insertion of battery and input power
source, check the sequence of how the circuit powers-up to make
sure that there are no sequences that can lead to a failure or
hazardous condition.
A common adverse operating condition is lightning caused
transients. A 500 mW zener diode across the input terminals
handles positive and negative transients caused by lightning. The
zener will fail short-circuited, if the energy exceeds its surge energy
ratings. To help protect the protection zener, place a small inductor
or low value resistor in series from the input source. This will lower
the peak voltage and energy and distribute it over a longer period.
NE57611
Product data