LP3925 Datasheet, PDF (40/51 Pages) Texas Instruments – High Performance Power Management Unit for Handset Applications

FIGURE 21. SIM Interface Level Shifters
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Comparators
Two general purpose comparators are available, which can
be used for detecting the plugging of external accessories or
other events. Voltage comparators are available on multi-
functional pins INP1 and INP2. 8 comparison thresholds are
available between 400 mV and 2400 mV, the values can be
found in the multifunction pins section. Comparator state is
available from registers as a read-only bit, or from multifunc-
tional pins as a direct data output. It is also possible to
generate an interrupt every time the comparator state
changes.
COMPARATOR ELECTRICAL CHARACTERISTICS
Typical values and limits appearing in normal type apply for T_J = 25°C. Limits appearing in boldface type apply over the entire
junction temperature range for operation, T_J = −40°C to +125°C. Unless otherwise specified, the following applies for V_BATT = 3.6V.
(Note 6)
Symbol
V_TH
V_TH2
I_IL
Parameter
Input Threshold Voltage
Input threshold voltage 2
Input leakage current
Conditions
Default Setting
Default Setting
INP1, INP2
0 ≤ V_INPUT ≤ V_VIN1.
Typ.
0.6
1
Limits
Min
Max
−1
1
Units
V
µA
ADC
LP3925 is equipped with a 12-bit ADC that has 8 inputs for
measuring charging current, discharge current, battery volt-
age (measuring at BATT pin), backup battery voltage, charger
input voltage, VDD, temperature and external signal through
GPIO.
The inputs are scaled linearly to adapt the voltage/current
range of the source to the input voltage range of the A/D core.
The ADC is clocked by the internal 4MHz system clock. The
conversion result is available in the registers 0x88 and 0x89
in 3ms after the setting of the ADC CONV START bit in the
0x87 Register. The ADC will automatically enter power save
mode if conversions are not performed.
allows starting the conversion, source selection and output
format selection. Setting the ADC CONV START bit in the
control register starts a new A/D conversion. Setting
ADC_FORMAT bit to 1 allows throwing out the MSB and
shifting the result 1 bit left. This can be used if result’s MSB
is known, to get more data with one register read.
BATTERY DISCHARGE CURRENT MEASUREMENT
The discharge current is measured indirectly by measuring
the voltage drop produced by discharge current on the
Rsense. The calculation of the current value is done by equa-
tion below:
A/D CONVERTER DATA AND CONTROL REGISTERS
Two read only registers 0x88 and 0x89 provide access to the
a/d conversion result. 8 most significant bits of the data can
be accessed in one read cycle. The Read/Write 0x87 register
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