DS1672

10 of 15

Trickle Charger

The trickle charger is controlled by the trickle charge register. The simplified schematic of Figure 5

shows the basic components of the trickle charger. The trickle charge select (TCS) bit (bits 4–7) controls

the selection of the trickle charger. In order to prevent accidental enabling, only a pattern on 1010 will

enable the trickle charger. All other patterns will disable the trickle charger. The DS1672 powers up with

the trickle charger disabled. The diode select (DS) bits (bits 2, 3) select whether or not a diode is

of the resistor is. The resistor selected by the resistor select (RS) bits and the diode selected by the diode

select (DS) bits are as follows:

TCS

TCS

TCS

TCS

DS

DS

RS

RS

FUNCTION

X

X

X

X

0

0

X

X

Disabled

X

X

X

X

1

1

X

X

Disabled

X

X

X

X

X

X

0

0

Disabled

1

0

1

0

0

1

0

1

No diode, 250

Ω resistor

1

0

1

0

1

0

0

1

One diode, 250

Ω resistor

1

0

1

0

0

1

1

0

No diode, 2k

Ω resistor

1

0

1

0

1

0

1

0

One diode, 2k

Ω resistor

1

0

1

0

0

1

1

1

No diode, 4k

Ω resistor

1

0

1

0

1

0

1

1

One diode, 4k

Ω resistor

0

0

0

0

0

0

0

0

Initial default value--disabled

Warning: The resistor value of 250

Ω must not be selected whenever V

than 3.63V.

Diode and resistor selection is determined by the user according to the maximum current desired for

battery or super cap charging. The maximum charging current can be calculated as illustrated in the

charge current will decrease.