14
POWER FUNCTIONALITY
The LPC47B34x has three power planes: VCC, VTR and VBAT.
VCC Power
The LPC47B34x is a 3.3 Volt part. The VCC supply is 3.3 Volts (nominal). See the “Operational
Description” section. See also the “Maximum Current Values” subsection of the “Power Functionality”
section.
VTR Support
The LPC47B34x requires a trickle supply (V
TR
) to provide sleep current for the programmable wake-up
events in the PME interface when V
CC
is removed. The VTR supply is 3.3 Volts (nominal). See the
“Operational Description” section. The maximum VTR current that is required depends on the
functions that are used in the part. See the “Trickle Power Functionality” and the “Maximum Current
Values” subsections of the “Power Functionality” section. If the LPC47B34x is not intended to provide
wake-up capabilities on standby current, V
TR
can be connected to V
CC
. The V
TR
pin generates a V
TR
Power-on-Reset signal to initialize the components that are powered by VTR.
Note: If V
TR
is to be used for programmable wake-up events when V
CC
is removed, V
TR
must be at its
full minimum potential at least 10
μ
s before V
CC
begins a power-on cycle. When V
TR
and V
CC
are fully
powered, the potential difference between the two supplies must not exceed 500mV.
VBAT Power
The LPC47B34x requires a battery supply (VBAT) to provide battery functionality to certain pins,
registers and logic. The VBAT supply is 3.3 Volts (nominal). See the “Operational Description”
section. See also the “Battery Power Functionality” and the “Maximum Current Values” subsection of
the “Power Functionality” section.
Internal PWRGOOD
An internal PWRGOOD logical control is included to minimize the effects of pin-state uncertainty in
the host interface as V
CC
cycles on and off. When the internal PWRGOOD signal is “1” (active), V
CC
>
2.3V (nominal), and the LPC47B34x host interface is active. When the internal PWRGOOD signal is
“0” (inactive), V
CC
<= 2.3V (nominal), and the LPC47B34x host interface is inactive; that is, LPC bus
reads and writes will not be decoded.
The LPC47B34x device pins nIO_PME, CLOCKI32, KDAT, MDAT, RING, nRI1, nRI2, RXD2 and
GPIOs (as input) are part of the PME interface and remain active when the internal PWRGOOD signal
has gone inactive, provided V
TR
is powered. The COLOR and BLINK pins also remain active when the
internal PWRGOOD signal has gone inactive, provided V
TR
is powered. The nINTRSN pin also
remains active when the internal PWRGOOD signal is inactive, however, this is a battery powered pin,
so it is functional as input even if V
TR
is not powered.
32.768 kHz Trickle Clock Input
The LPC47B34x utilizes a 32.768 kHz trickle clock input to supply a clock signal for the WDT, ring
filter, LED blink, wake on specific key function. See the following section for more information.