ATR0635_08 Datasheet, PDF (21/35 Pages) ATMEL Corporation – ANTARIS4 Single-chip GPS Receiver SuperSense

ATR0635
Figure 4-1. Connecting Example: Separate Power Supplies for RF and Digital Part Using the Internal LDOs
ATR0635 internal
2.7V to 3.3V
2.3V to 3.6V
NSHDN
VCC1
VCC2
VBP
VDIG
LDO_IN
LDO_EN
LDO_OUT
RF
ldoin
ldoen
ldoout
LDO18
4928H–GPS–06/08
1.5V to 3.6V
1 µF
(X7R)
VDD18
VDDIO
LDOBAT_IN
VBAT
1 µF
(X7R)
VBAT18
Core
1.8V to 3.3V
variable I/O domain
ldobat_in
vbat
vbat18
LDOBAT
VDD
RTC
backup memory
0V or 3V to 3.6V
VDDUSB
USB SM and
transceiver
The ATR0635 contains a built in low dropout voltage regulator LDO18. This regulator can be
used if the host system does not provide the core voltage VDD18 of 1.8V nominal. In such case,
LDO18 will provide a 1.8V supply voltage from any input voltage VDD between 2.3V and 3.6V.
The LDO_EN input can be used to shut down VDD18 if the system is in standby mode.
If the host system does supply a 1.8V core voltage directly, this voltage has to be connected to
the VDD18 supply pins of the Core. LDO_EN must be connected to GND. LDO_IN can be con-
nected to GND. LDO_OUT must not be connected.
A second built in low dropout voltage regulator LDOBAT provides the supply voltage for the RTC
and backup SRAM from any input voltage VBAT between 1.5V and 3.6V. The backup battery
delivers the supply current if LDOBAT_IN is not powered.
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