Microchip Technology MCP73833EV Data Sheet

© 2009 Microchip Technology Inc.

DS22005B-page 17

5.1.1

BATTERY MANAGEMENT INPUT 
SUPPLY (V

DD

)

The V

DD

 input is the input supply to the MCP73833/4.

The MCP73833/4 automatically enters a Power-down
mode if the voltage on the V

DD

 input falls below the

UVLO voltage (V

STOP

). This feature prevents draining

the battery pack when the V

DD

 supply is not present.

5.1.2

CURRENT REGULATION SET 
(PROG)

Fast charge current regulation can be scaled by placing
a programming resistor (R

PROG

) from the PROG input

to V

SS

. The program resistor and the charge current

are calculated using the 

:

The preconditioning trickle-charge current and the
charge termination current are ratiometric to the fast
charge current based on the selected device options.

5.1.3

BATTERY CHARGE CONTROL 
OUTPUT (V

BAT

)

The battery charge control output is the drain terminal
of an internal P-channel MOSFET. The MCP73833/4
provides constant current and voltage regulation to the
battery pack by controlling this MOSFET in the linear
region. The battery charge control output should be
connected to the positive terminal of the battery pack.

5.1.4

TEMPERATURE QUALIFICATION 
(THERM)

The MCP73833/4 continuously monitors battery
temperature during a charge cycle by measuring the
voltage between the THERM and V

SS

 pins. An internal

50 µA current source provides the bias for most
common 10 k

Ω negative-temperature coefficient

(NTC) or positive-temperature coefficient (PTC)
thermistors.The current source is controlled, avoiding
measurement sensitivity to fluctuations in the supply
voltage (V

DD

). The MCP73833/4 compares the voltage

at the THERM pin to factory set thersholds of 1.20V
and 0.25V, typically. Once a volage outside the
thresholds is detected during a charge cycle, the
MCP73833/4 immediately suspends the charge cycle.
The MCP73833/4 suspends charge by turning off the

pass transistor and holding the timer value. The charge
cycle resumes when the voltage at the THERM pin
returns to the normal range.
If temperature monitoring is not required, place a
standard 10 k

Ω resistor from THERM to V

SS

.

5.1.4.1

System Test (LDO) Mode

The MCP73833/4 can be placed in a system test mode.
In this mode, the MCP73833/4 operates as a low
dropout linear regulator (LDO). The output voltage is
regulated to the factory set voltage regulation option.
The available output current is limitted to the
programmed fast charge current. For stability, the V

BAT

output must be bypassed to V

SS

 with a minimum

capacitance of 1 µF for output currents up to 250 mA.
A minimum capacitance of 4.7 µF is required for output
currents above 250 mA.
The system test mode is entered by driving the THERM
input greater than (V

DD

-100 mV) with no battery

connected to the output. In this mode, the MCP73833/
4 can be used to power the system without a battery
present.

5.2.1

STATUS INDICATORS AND POWER 
GOOD (PG - OPTION)

The charge status outputs have two different states:
Low (L), and High Impedance (Hi-Z). The charge status
outputs can be used to illuminate LEDs. Optionally, the
charge status outputs can be used as an interface to a
host microcontroller. 

 summarize the state of

the status outputs during a charge cycle.

Where:

R

PROG

= kilo-ohms

I

REG

= milliampere

Note 1: I

THERM

 is disabled during shutdown,

stand-by, and system test modes.

2: A pull-down current source on the

THERM input is active only in stand-by
and system test modes.

3: During system test mode, the PROG

input sets the available output current
limit.

4: System test mode shall be exited by

releasing the THERM input or cycling
input power.

Shutdown

Hi-Z

Hi-Z

Hi-Z

Standby

Hi-Z

Hi-Z

L

Charge in Progress

L

Hi-Z

L

Charge Complete (EOC)

Hi-Z

L

L

Temperature Fault

Hi-Z

Hi-Z

L

Timer Fault

Hi-Z

Hi-Z

L

System Test Mode

L

L

L