ATR0622 Datasheet, PDF (18/26 Pages) ATMEL Corporation – GPS Baseband Processor

The baseband IC 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 however supply a 1.8V core voltage directly, this voltage has to be
connected to the VDD18 supply pins of the baseband IC. LDO_EN must be connected to
GND. LDO_IN can be connected 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 LDOBAT_IN between 2.3V and 3.6V or from
VBAT between 1.5V and 3.6V. The backup battery connected to VBAT is only discharged if
the supply connected to LDOBAT_IN is shut-down.
Only after VDD18 has been supplied to ATR0622 the RTC section will be initialized properly. If
only VBAT is applied first, the current consumption of the RTC and backup SRAM is
undetermined.
Figure 4-2. External Wiring Example Using 1.8V from Host System and Backup Power
Supply
ATR0622 internal
LDO_IN
LDO_EN
LDO_OUT
ldoin
ldoen
ldoout
LDO18
1.65V to 1.95V
VDD18
Core
2.3V to 3.6V
1.5V to 3.6V
1 µF
(X7R)
VDDIO
1 µF
(X7R)
LDOBAT_IN
VBAT
VBAT18
1.8V to 3.3V
variable IO Domain
ldobat_in
vbat
vbat18
LDOBAT
vdd
RTC
Backup Memory
0 to 2V or 3V to 3.6V
VDDUSB
USB SM and
Transceiver
18 ATR0622 [Preliminary]
4891CS–GPS–01/06