MP26058-28V, 1A LI + LINEAR BATTERY CHARGER WITH TIMER AND LDO MODE

MP26058 Rev. 0.91

www.MonolithicPower.com

8

1/25/2010

MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.

© 2010 MPS. All Rights Reserved.

Programming of Charge Current and Battery

Full Current

The relationship of the charge current and the

programming resistance is established by the

following table and graph.

1.65

1000

1.82

900

2.05

800

2.32

700

2.74

600

3.3

500

4.12

400

5.6

300

8.66

200

16.9

100

Charge Current vs

1000

900

800

700

600

500

400

300

200

0

0.2

0.1

0.3 0.4

0.6 0.7

0.5

Resistance

The recommended resistance for programming

the IBF pin to GND:

BF

BF

R

k

7

.

1

A

1

I

Ω

×

=

CHG

is used to indicate charging status. When

the battery full condition is reached or any other

condition prevents the charger from charging,

CHG

will become a floating.

Timer Operation

The TMR pin is used to set the internal

oscillator frequency:

OSC

TMR

F

F11Hz

C

µ

=×

The on-chip timer will start count down after

initial power-up or every time being enabled.

This timer will limit the max charge time when

battery is short to ground to 16384 internal

oscillating cycles, or if the total charge time

exceeds 262144 cycles and the battery full has

not been qualified, then it will terminate the

charger and a fault will be set by flashing CHG

LED at the rate of half the internal oscillation

frequency.. After fault reporting, the charger can

be re-initiated only by recycling the power

supply or SHDN\ signal. The timer function can

be disabled by shorting TMR pin to ground.

Negative Thermal Coefficient (NTC)

Thermistor

The MP26058 has a built-in NTC resistance

window comparator. If configured as the typical

application circuit as indicated in Figure 1, the

temperature range of 0°C to 50°C for the

TH11-4H104F NTC resistor.

Thermal Protection

The

MP26058

has

proprietary

thermal

protection to prevent the IC from overheating.

When in thermal protection mode, the charge

current will reduce to maintain the safe junction

temperature. Operating in thermal protection

mode will slow down the charging process.

Lowering the input voltage and enhancing

thermal dissipation to the environment can

effectively prevent the IC from going into

thermal protection mode.