4.5 Maximum Operating Limits
The maximum input voltage rating must be observed.
The TCM680 will clamp the input voltage to 5.8V.
Exceeding this maximum threshold will cause exces-
sive current to flow through the TCM680, potentially
causing permanent damage to the device.
4.6 Switched Capacitor Converter
Power Losses
The overall power loss of a switched capacitor
converter is affected by four factors:
1. Losses from power consumed by the internal
oscillator, switch drive, etc. These losses will
vary with input voltage, temperature and
oscillator frequency.
2. Conduction losses in the non-ideal switches.
3. Losses due to the non-ideal nature of the
external capacitors.
4. Losses that occur during charge transfer from
the pump to reservoir capacitors when a voltage
difference between the capacitors exists.
The power loss for the TCM680 is calculated using the
following equation:
EQUATION
PLOSS = (IOUT+)2 X ROUT- + (IOUT-)2 X ROUT+ + IIN X VIN
TCM680
© 2005 Microchip Technology Inc.
DS21486C-page 7