MCP73871 Microchip Technology, MCP73871 Datasheet - Page 17

• Manufacturer Part Number: MCP73871
• Description: Stand-Alone System Load Sharing and Li-Ion / Li-Polymer Battery Charge Management Controller
• Manufacturer: Microchip Technology

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3.14
The timer enable (TE) feature is used to enable or
disable the internal timer. A low signal on this pin
enables the internal timer and a high signal disables
the internal timer. The TE input can be used to disable
the timer when the system load is substantially limiting
the available supply current to charge the battery. The
TE input is compatible with 1.8V logic.
3.15
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 charge cycle resumes when the voltage at
the THERM pin returns to the normal range. The
charge temperature window can be set by placing fixed
value resistors in series-parallel with a thermistor.
Refer to Section 6.0 “Applications” for calculations
of resistance values.
© 2009 Microchip Technology Inc.
Note:
Timer Enable (TE)
Battery Temperature Monitor
(THERM)
10 kΩ
The built-in safety timer is available for the
following options: 4 HR, 6 HR and 8 HR.
negative-temperature
SS
pins. An internal
coefficient
3.16
With the CE input Low, the Li-Ion battery charger
feature of the MCP73871 will be disabled. The charger
feature is enabled when CE is active High. Allowing the
CE pin to float during the charge cycle may cause
system instability. The CE input is compatible with 1.8V
logic. Refer to Section 6.0 “Applications” for various
applications in designing with CE features.
3.17
There is an internal electrical connection between the
Exposed Thermal Pad (EP) and the V
be connected to the same potential.
Charge Enable (CE)
Exposed Thermal Pad (EP)
MCP73871
DS22090B-page 17
SS
pin; they must