MCP73123-22SSLASHMF datasheet(13/28 Pages) MICROCHIP

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 2009-2013 Microchip Technology Inc.

DS22191E-page 13

MCP73123/223

The charge current is established using a single

resistor from PROG to VSS. The program resistor and

the charge current are calculated using Equation 5-1

and Equation 5-2.

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 VBAT pin reaches the regulation voltage, VREG.

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 MCP73123/223 device

remains in this condition until the battery is removed. If

the battery is removed or input power is cycled, the

MCP73123/223 device enters the Standby mode,

where it remains until a battery is reinserted.

5.6

Constant Voltage Mode

When the voltage at the VBAT pin reaches the

regulation voltage, VREG, constant voltage regulation

begins. The regulation voltage is factory set to 3.6V for

a single cell, with a tolerance of ±0.5%; or 7.2V for dual

cells, with a tolerance of ±0.6%.

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 MCP73123/223 device continuously monitors the

voltage at the VBAT 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 MCP73123/223 device with no recharge option,

the MCP73123/223 will go into Standby mode when the

termination condition is met. The charge will not restart

until at least one of the following conditions have been

met:

• The battery is removed from the system and

inserted again

•VDD is removed and plugged in again

• RPROG is disconnected (or high impedance) and

reconnected

Charge

Current (mA)

Recommended

E96 Resistor (

)

Recommended

E24 Resistor (

)

130

10k

150

8.45k

8.20k

200

6.20k

250

4.99k

5.10k

300

4.02k

3.90k

350

3.40k

3.30k

400

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

800

1.40k

1.50k

850

1.33k

1.30k

900

1.24k

1.20k

950

1.18k

1.20k

1000

1.10k

1100

1.00k

REG

1104

0.93

–



Where:

RPROG

=kilo-ohms (k

)

IREG

milliampere (mA)

PROG

RE G

1104





log

0.93

–







Where:

RPROG

=kilo-ohms (k

)

IREG

milliampere (mA)

Note:

The MCP73123/223 also offer options

with no automatic recharge.

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