Rainbow Electronics ATmega8HVD - Manual (Page 102)

102
8052B–AVR–09/08
ATmega4HVD/8HVD
V
DROP
depends on actual current drawn from VREG.
Figure 19-2. Regulator Short-circuit Detection Example
19.5 Register Description
19.5.1 ROCR – Regulator Operating Condition Register
• Bit 7 – ROCS: ROC Status
When the VFET voltage is below V
FORCE
, this bit is set. When this is set, it is either an indica-
tion that the Voltage Regulator has entered the Battery Pack short mode (if RSCDEN is set) or
that the Voltage regulator is operating in FORCE mode (if RSCDEN is cleared).
• Bit 6:3 – Res: Reserved
These bits are reserved and will always read as zero.
• Bit 2 – RSCDEN: Regulator Short-Circuit Detection Enable
If this bit is set, the Voltage Regulator will enter the Battery Pack Short mode if VFET drops
below V
FORCE
. If the bit is cleared, the Voltage Regulator will enter FORCE mode under the
same condition. The ROCS bit can be used to indicate if VFET is above or below the V
FORCE
threshold.
The RSCDEN bit should normally never be set when VFET is below V
FORCE
since this will
eventually lead to a power-off condition when CREG has been discharged. For this reason,
the default value of RSCDEN is always 0. For the same reason, RSCDEN should always be
cleared when operating in DUVR mode. During charging, when VFET passes V
FORCE+
and the
ROCS bit is cleared, the RSCDEN bit must be set to be able to sustain operation during short
spikes on VFET.
• Bit 1 – ROCWIF: ROC Warning Interrupt Flag
: The ROCWIF flag is set if RSCDEN is set and ROCS goes high. The bit can be cleared by
writing a logic '1' to its bit location.
• Bit 0 – ROCWIE: ROC Warning Interrupt Enable
2.2V
V
FORCE-
V
VREG
t
VFET
V
FORCE+
V
BLOT, normal
Bit 7 6 5 4 3 2 1 0
ROCS - - - - RSCDEN ROCWIF ROCWIE ROCR
Read/Write R R R R R R/W R/W R/W
Initial Value 0 0 0 0 0 0 0 0