Low Side Battery Sensor IC
The AS8515 is a Data Acquisition System with Power Management and LIN Transceiver for 12V Battery Sensor Applications.
It 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 ±160 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.
- A precision voltage attenuator with power down facility
- LIN 2.1 transceiver
- Power-On Reset with OTP adjustable reset timeout and brownout
- 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, LIN bus pin, 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
- Programmable gain, low noise amplifier for current channel with gain stages 5, 25, 40, 100
- 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 AS8515 is suitable for battery sensors, having shunt current sensor at minus pole. For lead acid, AGM, 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.
AS8515 Block Diagram