MCP73871-2AAI/SS Microchip Technology, MCP73871-2AAI/SS Datasheet - Page 18

• Manufacturer Part Number: MCP73871-2AAI/SS
• Description: USB/AC Battery Charger With Power Path Management 20 SSOP .209in TUBE
• Manufacturer: Microchip Technology

Specifications of MCP73871-2AAI/SS

• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

MCP73871
4.6
When the voltage at the V
regulation voltage, V
begins. The regulation voltage is factory set to 4.10V
or 4.20V with a tolerance of ±0.5%.
4.7
The charge cycle is terminated when, during constant
voltage mode, the average charge current diminishes
below a threshold established with the value of a
resistor connected from PROG3 to V
has expired. A 1 ms filter time on the termination
comparator ensures that transient load conditions do
not result in premature charge cycle termination. The
timer period is factory set and can be disabled. Refer to
Section 1.0 “Electrical Characteristics” for timer
period options.
The charge current is latched off and the MCP73871
device enters a charge complete mode.
4.8
The MCP73871 device continuously monitors the volt-
age at the V
voltage drops below the recharge threshold, another
charge cycle begins and current is once again supplied
to the battery or load. The recharge threshold is factory
set. Refer to Section 1.0 “Electrical Characteristics”
for recharge threshold options.
DS22090A-page 18
Note:
CONSTANT VOLTAGE MODE
CHARGE TERMINATION
AUTOMATIC RECHARGE
Charge
recharge features avoid constant charging
Li-Ion batteries to prolong life of Li-Ion
batteries while keeping their capacity at
healthy level.
BAT
pin in the charge complete mode. If the
REG
termination
, constant voltage regulation
BAT
SS
pin reaches the
and
or internal timer
automatic
4.9
The MCP73871 device limits the charge current based
on the die temperature. The thermal regulation opti-
mizes the charge cycle time while maintaining device
reliability.
the MCP73871 device. Refer to Section 1.0 “Electri-
cal Characteristics” for thermal package resistances
and Section 6.1.1.2 “Thermal Considerations” for
calculating power dissipation.
.
FIGURE 4-3:
4.10
The MCP73871 device suspends charge if the die tem-
perature exceeds 150°C. Charging will resume when
the die temperature has cooled by approximately 10°C.
The thermal shutdown is a secondary safety feature in
the event that there is a failure within the thermal
regulation circuitry.
4.11
The MCP73871 device continuously monitor battery
temperature during a charge cycle by measuring the
voltage between the THERM and V
50 µA current source provides the bias for most
common
thermistors (NTC). The MCP73871 device compares
the voltage at the THERM pin to factory set thresholds
of 1.24V and 0.25V, typically. Once a voltage outside
the thresholds is detected during a charge cycle, the
MCP73871 device immediately suspends the charge
cycle. The MCP73871 device suspends charge by
turning off the charge pass transistor and holding the
timer value. The charge cycle resumes when the
voltage at the THERM pin returns to the normal range.
1200
1000
800
600
400
200
0
Thermal Regulation
THERMAL SHUTDOWN
TEMPERATURE QUALIFICATION
25
Figure 4-3
10 kΩ
V
R
DD
PROG
= 5.2V
= 1 kΩ
50
Ambient Temperature (°C)
negative-temperature
depicts the thermal regulation for
Thermal Regulation
© 2008 Microchip Technology Inc.
75
100
SS
pins. An internal
125
coefficient
150