pc87591l-n05 National Semiconductor Corporation, pc87591l-n05 Datasheet - Page 322

• Manufacturer Part Number: pc87591l-n05
• Description: Lpc Mobile Embedded Controller
• Manufacturer: National Semiconductor Corporation

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Host-Controlled Modules and Host Interface
6.2.9
The PC87591L-N05 is supplied from four supply voltages, as shown in Figure 108 (see Section 3.1 on page 58 for more
detailed description):
A standby voltage (V
Figure 109 shows a typical battery configuration. No external diode is required to meet the UL standard, because of the in-
ternal switch and internal serial resistor R
RTC power is supplied from either V
parator delivers the control signals to a pair of switches. When V
voltage (V
disconnection of the external AC/DC input power supply or disconnection of the main battery. Figure 109 illustrates the
mechanism whereby V
To assure that the module uses power from V
mum (V
V
The actual voltage point where the PC87591L-N05 switches from V
voltage but high enough to guarantee the correct functionality of the oscillator and the CMOS RAM.
• System power supply voltage, V
• System analog power supply voltage, AV
• System standby power supply voltage, V
• Backup voltage, from low-capacity Lithium battery
BAT
(thin black line) and vice-versa for generating V
CC2PP
Power Supply
BAT
) maintains the correct time and saves the CMOS memory when the V
), as detailed in Chapter 7 on page 334. Figure 110 illustrates the switching between V
CC
CC
) from the external AC/DC power supply powers the RTC under normal conditions.
or V
BAT
1. Place a 0.1 F capacitor on each V
2. Place a 10-47 F capacitor on the common power
V
is selected.
ACPI Controller
PP
pin as close as possible to the pin, and also on V
supply net as close as possible to the device.
DD
CC
RTC
Figure 109. Typical Battery Configuration
Figure 108. Power Supply Connections
or V
UL
.
BAT
CC
V
CC
PC0
V
CC
V
BAT
DD Sense
CC
voltage source, according to the sources’ levels. An internal voltage com-
and not from V
RTC
PP
V
V
BAT
V
CC
(thick black line).
REF
322
CC
BAT
(Continued)
ONCTL
V
AV
V
V
V
is active, the RTC power is drawn from it. Battery backup
V
R
BAT
DD
CC
BAT
, the V
BAT
CC
UL
CC
CC
External AC Power
to V
power supply
0.1 F
0.1
CC
ONCTL
V
CC
V
Supply
DD
Backup
Battery
Power
CF
CC
CF
voltage should be maintained above its mini-
is lower than the minimum workable battery
F
CC
BAT
voltage is absent due to power failure,
BT1
V
.
CC
CC
(thick gray line) and
Revision 1.2