lp8765rlx National Semiconductor Corporation, lp8765rlx Datasheet - Page 23

• Manufacturer Part Number: lp8765rlx
• Description: High Performance Power Management Unit For Handset Applications
• Manufacturer: National Semiconductor Corporation

VCOIN
ICOIN
R
I
I
LEAK
RTC
VCOIN
Backup Battery Charger
Backup battery charger (BBC) is intended for charging an ex-
ternal coin cell battery. Its output is connected to the VCOIN
pin. It consists of Voltage Limited Current Source with 1kΩ
output resistor. By default it is always on.
It is possible to turn backup battery charger off via registers.
VCOIN – voltage limit and ICOIN – current source values are
also programmable via registers (the possible values are stat-
ed in
protection. VCOIN pin voltage can be measured by an internal
ADC.
Typical values and limits appearing in normal type apply for T
junction temperature range for operation, T
(Note
32.768 kHz Crystal Oscillator
There are two options for implementing the 32.768 kHz os-
cillator:
1.
Symbol
ALARMX MONDAY/ TUESDAY/
FRIDAY/ SATURDAY/SUNDAY
An external crystal that is connected between XIN and
XOUT. The external crystal ESR must not exceed 100
kΩ; if this value is exceeded the circuit may never start
oscillating.
WEDNESDAY/ THURSDAY/
Backup Battery
6)
ALARMX DAY OF MONTH Day of month setting for alarm; 0x1F to ignore day of month
ALARMX ACTIVATED
Voltage limit
Charging current
Internal series resistor
Reverse leakage current
COIN input current
ALARMX MINUTES Minute setting for alarm; 0x3F to ignore minutes
ALARMX MONTH Month setting for alarm; 0xF to ignore month
ALARMX HOURS Hour setting for alarm; 0x1F to ignore hours
ALARMX YEAR Year setting for alarm; 0x7F to ignore year
Charger). BBC has a reverse current
Parameter
BACKUP BATTERY CHARGER ELECTRICAL CHARACTERISTICS
Weekday selection for alarm; write '1' to allow alarm on that day
0 - Alarm not activated
1 - Alarm activated
J
= −40 to +125°C. Unless otherwise specified, the following applies for V
I
VCOIN programmed to 3V
VCOIN pin shorted to GND
ICOIN programmed to 200 µA
VRTC pin current = 0
V
LOAD
COIN
RTC TIME SELECTION TABLE 2
= 1µA
= 3V
Registers 0x54…0x62
Conditions
J
= 25°C. Limits appearing in boldface type apply over the entire
23
2.
Pins XIN and XOUT are not able to drive external load. Os-
cillator output is buffered to pin OSC_32KHZx.
An external oscillator module could be used by
connecting the module output directly into XIN. When
using an external oscillator module, the XOUT pin should
be unconnected.
FIGURE 2. BBC IU Characteristic
Typ
200
1.0
1.7
3V
−20%
−7%
Min
0.5
Limit
+20%
+7%
Max
1.6
10
5
VIN_CHG
www.national.com
µA
30162008
Units
= 5V.
µA
kΩ
µA
V