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PDF AS8515 Data sheet ( Hoja de datos )
| Número de pieza | AS8515 | |
| Descripción | Data Acquisition System | |
| Fabricantes | ams | |
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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
www.ams.com
Revision 0.7
1 - 65
1 page  
AS8515
Datasheet - Pin Assignments
4 Pin Assignments
Figure 2. Pin Assignments (Top View)
RSHH EN RESET Rx Tx CST INT
32 31
30 29 28 27
26 25
RSHL 1
VREF 2
VCM 3
AVDD 4
AVSS 5
ETR 6
ETS 7
VSENSE_IN 8
AS8515
24 CLK
23 SDI
22 MEN
21 CHOP_CLK
20 DVDD
19 DVSS
18 SDO
17 SCLK
9 10
VSENSE_GND LIN
11 12 13
VSS VSENSE VSUP
14
15 16
VCC CSB
4.1 Pin Descriptions
Table 1. Pin Descriptions
Pin Name
RSHL
Pin Number
1
VREF
2
VCM 3
AVDD 1
AVSS 2
4
5
Pin Type
Analog input
Analog output
Analog output
Analog input
Power supply
Description
Negative differential input for current channel
Internal reference voltage to Sigma Delta ADC;
Connect 100nF to AVSS from this pin.
Common mode voltage to the internal measurement path;
Connect 100nF to AVSS from this pin.
+3.3V Power-supply; Supplied by LDO output (VCC) in Top die;
Should be shorted to pin 21 (VCC) externally.
0V Power-supply Ground analog
www.ams.com
Revision 0.7
5 - 65
5 Page 
AS8515
Datasheet - AS8515 Top Die Overview
7 AS8515 Top Die Overview
The AS8515 Top die consists of a resistive divider, a low dropout regulator, and a LIN bus transceiver. Additionally integrated are a RESET unit
with a power-on-reset delay, programmable window watchdog and timeout watchdog timers as a factory programming option. It also includes a
watchdog timeout on LIN Tx node to indicate if the Microcontroller is stuck in a loop and the LIN bus remains in dominant time for more than the
necessary time.
7.1 Voltage Attenuator
A resistive divider is used as a battery voltage attenuator. Like the amplifier, the attenuator can be enabled or disabled through SPI, and in the
device standby mode, we additionally need logic high on MEN pin for enabling. Internal reverse polarity protection is provided for VSENSE pin.
Figure 3. Attenuator Implementation
VSENSE
PD
VSENSE_IN
VSENSE_GND
7.2 Voltage Regulators (LDO)
The device has a low-dropout voltage regulator named LDO, 3.3V voltage outputs. The output of the LDO is VCC. The regulator is always ON
except when the device enters the over-temperature shutdown.
The regulator has in-built short-circuit current limitation feature. The regulator can be temporarily shut down for hard reset of the external circuitry
by configuring the device to temporary shutdown mode through SPI.
The LDO power-up happens when the POR-VSUP event occurs (RESET_VSUP_N switching from low to high). The LDO will be switched off if
there is an under voltage on VCC, that is, when RESET_VCC_N switches back to low.
7.3 LIN Transceiver
The device has a LIN transceiver with slew-controlled bus driver for controlling the electromagnetic emissions from the LIN bus. Further, the slew
rate is independent of the bus load. The transmitter relays the data from the LIN controller (Tx pin) to the bus (LIN pin), and the receiver provides
the data on the bus to the controller (Rx pin). The transceiver conforms to the LIN 2.1 standard.
The LIN transceiver has a timeout watchdog for Tx. After the timeout, the LIN bus will be released to the recessive state from the dominant state.
The bus driver has an in-built short-circuit current limitation facility to protect the device from damage when there is a short between the bus and
the supply. In addition to the data receiver, there is a low-power receiver active in the device standby mode which received a wake-up event from
the LIN bus to bring the device to normal mode.
7.4 Temperature Monitor/Limiter
The temperature limiter circuit powers down the device when the junction temperature exceeds 170°C (nominal). It also issues an over-
temperature warning at 160°C (nominal). The device is powered up again when the junction temperature falls below 140°C (nominal). The over-
temperature warning flag is also cleared at this temperature.
The temperature limiter circuit can be optionally disabled through SPI.
www.ams.com
Revision 0.7
11 - 65
11 Page | ||
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