ASM805LCPA PULSECORE [PulseCore Semiconductor], ASM805LCPA Datasheet - Page 5

• Manufacturer Part Number: ASM805LCPA
• Description: ?P Power Supply Supervisor With Battery Backup Switch
• Manufacturer: PULSECORE [PulseCore Semiconductor]

April 2008
rev 1.7
Table 2: Maximum Battery Voltages
Although most batteries that meet the requirements of
Table2 are acceptable, lithium batteries are very effective
backup source due to their high-energy density and very
low selfdischarge rates.
Battery replacement while Powered
Batteries can be replaced even when the device is in a
powered state as long as V
threshold voltage V
V
occur in some other supervisory circuits. If V
used, the pin should be grounded.
Backup Power Sources - SuperCap™
Capacitor storage, with very high values of capacitance,
can be used as a back-up power source instead of
batteries. SuperCap
the fractional farad range. A 0.1 farad SuperCap™ would
provide a useful backup power source. Like the battery
supply, it is important that the capacitor voltage remain
below the maximum voltages shown in Table 2. Although
the circuit of Figure 4 shows the most simple way to
connect the SuperCap™, this circuit cannot insure that an
over voltage condition will not occur since the capacitor
will ultimately charge up to V
voltage condition does not occur, the circuit of Figure 5 is
preferred. In this circuit configuration, the diode-resistor
pair clamps the capacitor voltage at one diode drop below
V
Part Number
BATT
CC
ASM802M
ASM690A
ASM802L
ASM805L
ASM692A
. V
pin will not cause a powersupply switchover as can
CC
itself should be regulated within ±5% of 5V for
RT
™
µP Power Supply Supervisor With Battery Backup Switch
MAXIMUM Battery Voltage (V)
. In the ASM devices, a floating
are capacitors with capacities in
CC
remains above the reset
CC
. To insure that an over
Notice: The information in this document is subject to change without notice.
4.80
4.80
4.80
4.55
4.55
BATT
is not
the ASM692A/802M or within ±10% of 5V for the
ASM690A/802L/805L to insure that the storage capacitor
does not achieve an over voltage state.
Note: SuperCap
Operation without a Backup Power Source
When operating without a back-up power source, the
V
be connected to V
not occur. Connecting V
drop due to the ON-resistance of the PMOS switch.
BATT
pin should be connected to GND and V
TM
is a trademark of Baknor Industries
CC
, since power source switchover will
OUT
ASM690A/692A
ASM802L/802M
to V
CC
eliminates the voltage
ASM805L
5 of 15
OUT
should