AS8515Low Side Battery Sensor IC - 62 Pages

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AS8515Low Side Battery Sensor IC

Catalog excerpts

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. External Sensors: 2 Key Features A precision voltage attenuator with power down facility LIN 2.1 transceiver Power-On Reset with programmable reset timeout and brownout 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 batterysensing pins, and LIN bus pin Over temperature warning & shutdown functions Two independent high resolution A/D converters with programmable over sampling ratio 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 sampling rate up to 4kHz throughput Programmable gain, low noise amplifier for current channel with gain stages 5, 25, 40, 100

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Voltage Channel To voltage channel ADC Multiplexer, Current Source Low Precision Clock POR_VSUP High Precision Clock RSHL VSENSE Figure 1. AS8515 Block Diagram Temperature Limiter Voltage Channel ADC VSENSE_GND SPI, Comparator, Filter Option Reference Generator

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4 Pin Assignments Figure 2. Pin Assignments (Top View) 4.1 Pin Descriptions Table 1. Pin Descriptions Pin Name Analog input Negative differential input for current channel Analog output Internal reference voltage to Sigma Delta ADC; Connect 100nF to AVSS from this pin. Analog output Common mode voltage to the internal measurement path; Connect 100nF to AVSS from this pin. Analog input +3.3V Power-supply; Supplied by LDO output (VCC) in Top die; Should be shorted to pin 21 (VCC) externally. Power supply 0V Power-supply Ground analog AVDD AVSS

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Table 1. Pin Descriptions Pin Name Analog input Power supply 0V Power-supply Ground analog Analog input Battery voltage input Connect 100nF to VSS from this pin. Power supply Supply input from battery (through external reverse polarity protection device) Analog output Digital input Chip select for Bottom die Digital input Pin Type Analog input Description Voltage channel single ended input Battery voltage attenuator output and voltage channel input Input signal for voltage channel (low) LIN BUS Regulated 3.3V output supply for loads up to 50mA Digital output Power supply Analog input +3.3V...

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5 Absolute Maximum Ratings Stresses beyond those listed in Table 2 may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in Electrical Characteristics on page 8 is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Table 2. Absolute Maximum Ratings Symbol Electrical Parameters VSUP Supply voltages Battery voltage inputs AVDD, DVDD Enable input Regulated output supplies VCC generated by Top die must not be larger than...

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6 Electrical Characteristics Unless otherwise noted in this specification, all defined tolerances of parameters are assured over the whole operation conditions range and also over lifetime. 6.1 Operating Conditions Table 3. Operating Conditions Symbol Supply voltages Battery voltage input Positive supply voltage Negative supply voltage Positive digital supply voltage Negative digital supply voltage Enable input Regulated output supply Ambient temperature Referring to DVSS, Typical ±10% Supply current System clock frequency Maximum junction temperature (TJ) is 130ºC When external clock is...

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SDI, SCLK. Table 6. SDI, SCLK Symbol High level input voltage Low level input voltage Input leakage current SDO Output. Table 7. SDO Symbol High level output voltage Low level output voltage Output current CHOP_CLK Output. Table 8. CHOP_CLK Symbol High level output voltage Low level output voltage Output current EN Input. Table 9. EN Symbol High level input voltage Low level input voltage Input leakage current Pull-down current High level input voltage Low level input voltage Input leakage current Pull-down current Output current High level output voltage Low level output voltage

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