Datasheet
MCP73213
DS22190B-page 18 © 2009 Microchip Technology Inc.
5.5 Constant Current Mode - Fast
Charge
During the constant current mode, the programmed
charge current is supplied to the battery or load.
The charge current is established using a single
resistor from PROG to V
SS
. The program resistor and
the charge current are calculated using the following
equation:
EQUATION 5-1:
EQUATION 5-2:
Table 5-1 provides commonly seen E96 (1%) and E24
(5%) resistors for various charge current to reduce
design time.
TABLE 5-1: RESISTOR LOOKUP TABLE
Constant current mode is maintained until the voltage
at the V
BAT
pin reaches the regulation voltage, V
REG
.
When constant current mode is invoked, the internal
timer is reset.
5.5.1 TIMER EXPIRED DURING
CONSTANT CURRENT - FAST
CHARGE MODE
If the internal timer expires before the recharge voltage
threshold is reached, a timer fault is indicated and the
charge cycle terminates. The MCP73213 device
remains in this condition until the battery is removed. If
the battery is removed or input power is cycled, the
MCP73213 device enters the Stand-by mode where it
remains until a battery is reinserted.
5.6 Constant Voltage Mode
When the voltage at the V
BAT
pin reaches the
regulation voltage, V
REG
, constant voltage regulation
begins. The regulation voltage is factory set to 8.2V,
8.4V, 8.7V or 8.8V with a tolerance of ± 0.5%.
5.7 Charge Termination
The charge cycle is terminated when, during constant
voltage mode, the average charge current diminishes
below a threshold established with the value of 5%,
7.5%, 10% or 20% of fast charge current
or internal
timer 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.
5.8 Automatic Recharge
The MCP73213 device continuously monitors the
voltage at the V
BAT
pin in the charge complete mode. If
the 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.
For the MCP73213 device with no recharge option, the
MCP73213 will go into standby mode when termination
condition is met. The charge will not restart until
following conditions have been met:
• Battery is removed from the system and inserted
again
•V
DD
is removed and plugged in again
• R
PROG
is disconnected (or high impedance) and
reconnected
Charge
Current (mA)
Recommended
E96 Resistor (Ω)
Recommended
E24 Resistor (Ω)
130 10k 10k
150 8.45k 8.20k
200 6.20k 6.20k
250 4.99k 5.10k
300 4.02k 3.90k
350 3.40k 3.30k
400 3.00k 3.00k
450 2.61k 2.70k
500 2.32k 2.37k
550 2.10k 2.20k
600 1.91k 2.00k
650 1.78k 1.80k
700 1.62k 1.60k
750 1.50k 1.50k
800 1.40k 1.50k
850 1.33k 1.30k
900 1.24k 1.20k
950 1.18k 1.20k
1000 1.10k 1.10k
1100 1.00k 1.00k
I
REG
1104 R
PROG
0.93–
×
=
Where:
R
PROG
= kilo-ohms (kΩ)
I
REG
= milliampere (mA)
R
PROG
10
I
REG
1104
------------
⎝⎠
⎛⎞
log
⎝⎠
⎛⎞
0.93–()
⁄
=
Where:
R
PROG
= kilo-ohms (kΩ)
I
REG
= milliampere (mA)
Note: The MCP73213 also offers options with no
automatic recharge.