MCP73831/2
4.5
Constant-Voltage Mode
4.8
Thermal Regulation
When the voltage at the V
BAT
pin reaches the regula-
tion voltage, V
REG
, constant voltage regulation begins.
The regulation voltage is factory set to 4.2V, 4.35V,
4.40V, or 4.50V with a tolerance of ±0.75%.
The MCP73831/2 limit the charge current based on
the die temperature. The thermal regulation optimizes
the charge cycle time while maintaining device
reliability. Figure 4-2 depicts the thermal regulation for
the MCP73831/2.
525
R
PROG
= 2 kΩ
4.6
Charge Termination
Charge Current (mA)
The charge cycle is terminated when, during Constant-
Voltage mode, the average charge current diminishes
below a percentage of the programmed charge current
(established with the value of the resistor connected to
the PROG pin). A 1 ms filter time on the termination
comparator ensures that transient load conditions do
not result in premature charge cycle termination. The
percentage or ratio of the current is factory set. Refer
to
for
charge termination current options and the
“Product
Identification System”
for standard options.
The charge current is latched off and the MCP73831/2
enter a Charge Complete mode.
450
375
300
225
150
75
0
25
35
45
55
65
75
85
95
105
115
125
135
145
155
Junction Temperature (°C)
FIGURE 4-2:
Thermal Regulation.
4.7
Automatic Recharge
4.9
Thermal Shutdown
The MCP73831/2 continuously monitor the voltage at
the V
BAT
pin in the Charge Complete mode. If the volt-
age 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
for recharge threshold options and the
Product Identification System for standard options.
The MCP73831/2 suspend charge if the die tempera-
ture exceeds 150°C. Charging will resume when the
die temperature has cooled by approximately 10°C.
©
2006 Microchip Technology Inc.
DS21984B-page 11
MICROCHIP [ MICROCHIP TECHNOLOGY ]
