LTC1325CSW datasheet(21/24 Pages) LINER

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LTC1325

APPLICATIONS INFORMATION

3. The MSBF bit is set depending on whether the micro-

processor clocks in serial data with MSB- or LSB-first.

4. The DS0 to DS2 bits can be anything except when

entering idle mode or when requesting for ADC read-

ings. In these cases, DS0 to DS2 are set to select the

desired reading: TBAT, VCELL or TAMB.

5. The PS bit should always be 0 so that the LTC1325

does not go into shutdown mode.

6. The DR0 to DR2 should not select any of the test modes.

It may assume different settings between Fast charge

and Top Off charge in order to alter the charging current.

7. The FSCLR bit should be set to 1 to clear any faults and

reset the timer when starting Discharge, Fast charge

or Top Off. The status bits that the LTC1325 returns

during the same I/O operation (that FSCLR is set to 1)

should be checked to determine if faults were indeed

cleared, i.e., discharging or charging has begun. This

is not shown in the simplified flowchart of Figure 6.

For commands other than the START commands,

FSCLR should be set to 0 so as not to reset the timer.

8. The TO0 to TO2 bits should all be set to 1 in discharge

mode to ensure discharge does not end prematurely

due to a timeout fault. During Fast charge or Top Off

charge, these bits are set to a value suitable for the

charge rate used. For example, if the charge rate is 1C,

the timeout period should be set to 80 minutes.

9. In charge mode, the CF capacitor filters the VCELL node

and sees a small ripple due to ripple at the Sense pin.

Prior to taking an ADC reading, the LTC1325 is put in

Figure 6. Simple Charging Algorithm

CONDITIONING?

EDV = 1?

TERMINATE?

CONDITIONING?

TERMINATE?

START

END

START

DISCHARGE

READ

STATUS

START

FAST CHARGE

IDLE MODE

AND WAIT

RESUME

FAST CHARGE

IDLE MODE

RESUME

TOP OFF CHARGE

WAIT

START

TOP OFF CHARGE

READ ADC

AND STATUS

READ ADC

AND STATUS

WAIT

YES

LTC1325 • F06

WAIT

IDLE MODE

AND WAIT

LTC1325CSW Datasheet(PDF) 21 Page - Linear Technology

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