Si9730

Vishay Siliconix

Document Number: 70658

S-40135—Rev. F, 16-Feb-04

www.vishay.com

9

Additionally, the battery as a whole can be undervoltage (UV),

necessarily

(though normally) mutually exclusive with the

other cell conditions: if one cell were at 0V, the other cell could

be in NO, and the battery could still be in UV.

The charger can be either present (ON) or not present (OFF);

the “X” in the table means the condition is true regardless of the

state of the charger. The load current can be either 0, normal

current that can be either 0 or normal. Finally, the switch can

be either ON, OFF, or cycling at either 1/8 or 7/8 duty cycle,

where the duty cycle refers to the portion of the period when

the switch is on; the notation On−>On simply means that the

switch does not change state, it remains on; the notation −>Off

means that the switch turns off regardless of its previous state.

STATE TRANSITION TABLE

High-Cell Voltage

Low-Cell Voltage

Charger On/Off

Load Current

Switch State

NO

NO

Off>On

X

On−>On

NO−>OC

NO

Off

0

On−>Off

NO

NO−>OC

Off

0

On−>Off

NO−>OC

NO

Off

Normal

Cycles at very high duty cycle

NO

NO−>OC

Off

Normal

Cycles at very high duty cycle

OC

NO

Off−>On

X

Off−>Off

NO

OC

Off−>On

X

Off−>Off

OC

OC

Off−>On

X

Off−>Off

NO

NO

Off

Normal−>Short

On−>Off

OC

NO

Off

Normal−>Short

On−>Off

NO

OC

Off

Normal−>Short

On−>Off

NO−>ODC

NO

Off

0

On−>Off

NO

NO−>ODC

Off

0

On−>Off

NO−>ODC

NO

Off

Normal

On−>Off

NO

NO−>ODC

Off

Normal

On−>Off

ODC

NO

Off−>On

X

Off−>Cycle at 7/8 duty cycle

NO

ODC

Off−>On

X

Off−>Cycle at 7/8 duty cycle

ODC

ODC

Off−>On

X

Off−>Cycle at 7/8 duty cycle

UV

Off−>On

X

Off−>Cycle at 1/8 duty cycle

NO−>ODC

OC

Off

0

Cycle−>Off

OC

NO−>OC

Off

0

Off

NO

NO

V<0

X

Off

UV

On

Center Tap−>Open

Cycle at 1/8 duty cycle

ODC

ODC

X

Center Tap−>Open

−.>Off

NO

ODC

X

Center Tap−>Open

−.>Off

ODC

NO

X

Center Tap−>Open

−.>Off

NO

NO

X

Center Tap−>Open

−.>Off

OC

OC

X

Center Tap−>Open

−.>Off