AS8515 Datasheet, PDF (1/65 Pages) ams AG – Data Acquisition System with Power Management and LIN Transceiver for 12V Battery Sensor Applications

AS8515
Data Acquisition System with Power Management and LIN Transceiver
for 12V Battery Sensor Applications
1 General Description
The AS8515 is designed for simultaneous measurement of shunt
current sensor signal and battery voltage by two independent ADC
channels. Both channels can measure small signals up to ±219 mV
versus ground through programmable gain amplifier or larger signals
in the 1V range without amplifier. After analog to digital conversion
and digital filtering, the resulting digital values are accessible through
4-wire serial interface. The device is powered directly from the
battery through LDO and provides a 3.3V supply for an external
microcontroller. For communication with the next level ECU, the
device offers a LIN 2.1 transceiver. Measurement of battery voltage
is supported through resistive attenuator with disable for power
saving in standby.
The device is a stacked die system providing a high voltage CMOS
IC for power management and transceiver functions as a Top die
and low voltage sensor interface functions as a Bottom die inside
a 32-pin MLF (5x5 mm) package.
Internal temperature sensor
Synchronous acquisition for both ADC channels
Reference-voltage source (high precision and high stability)
Offset auto zero architecture on both channels
Current monitoring comparator with interrupt signal generation
and µC clock enable. Timer with 2 related outputs for single
shot sampling of current and voltage channel in low power
mode.
Precision on chip RC oscillator or external clock. Low slew, low
EMC clock output which can be used by external
microcontroller which is enabled respectively disabled by mode
control through SPI and interrupt from current monitor in low
power mode.
The integrated circuit can execute measurements with internal and
external sensors and sources for the voltage channel and with
external sensor for the current channel.
2 Key Features
A precision voltage attenuator with power down facility
LIN 2.1 transceiver
Power-On Reset with programmable reset timeout and brown-
out detection through factory setting
A window Watchdog function in the normal mode and a timeout
Watchdog in the device standby mode as a factory option
Load dump protection (42V) for all battery supplied pins and
Enable pin
Internal reverse polarity protection (up to -27V) for all battery-
sensing pins, and LIN bus pin
Over temperature warning & shutdown functions
Two independent high resolution A/D converters with
programmable over sampling ratio
Programmable sampling rate up to 4kHz throughput
External Sensors:
Current measurement via Shunt resistor (4 ranges)
Battery voltage (internal voltage divider to battery)
ETR and ETS for external temperature sensor (with switchable
current source)
Internal Sensors:
On chip temperature sensor
Internal current sources for functional test of measurement path
and the connection of shunt resistor
3 Applications
The AS8515 is suitable for battery sensors, having shunt current
sensor at minus pole. For lead acid, Li-Ion batteries up to 18V
nominal, 42V over voltage capability.
The device is also ideal as a general purpose sensor interface for
automotive LIN slaves.
Programmable gain, low noise amplifier for current channel with
gain stages 5, 25, 40, 100
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