atr0625 ATMEL Corporation, atr0625 Datasheet - Page 18

• Manufacturer Part Number: atr0625
• Description: Gps Baseband Processor Supersense
• Manufacturer: ATMEL Corporation

18
ATR0625 [Preliminary]
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 ATR0625 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.
1.65V to 1.95V
2.3V to 3.6V
1.5V to 3.6V
0 to 2V or 3V to 3.6V
External Wiring Example Using 1.8V from Host System and Backup Power
Supply
1 µF
(X7R)
1 µF
(X7R)
LDOBAT_IN
LDO_OUT
VDDUSB
LDO_EN
LDO_IN
VBAT18
VDD18
VDDIO
VBAT
ldoin
ldoen
ldoout
ldobat_in
vbat
vbat18
variable IO Domain
Backup Memory
USB SM and
1.8V to 3.3V
Transceiver
Core
RTC
ATR0625 internal
LDOBAT
LDO18
vdd
4925A–GPS–02/06