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Data Sheet
AS8002
S o l a r P h o t o v o l t a i c I n v e r t e r M e a s u r em e n t I C w i t h F a s t O v e r C u r r e n t
Detection
The AS8002 is a highly accurate measurement IC that allows
monitoring the generated energy with low cost shunt resistors or
other sensors for the current and resistor dividers for the voltage.
Programmable gain amplifiers to accommodate for different
sensors
Three multiplexed inputs to the 12-Bit ADC for secondary
measurements that require high accuracy and fast sampling
rates
On chip temperature sensor connected to one of the inputs of
the multiplexer
On-chip voltage reference with small temperature coefficient
(10ppm/K typ). This reference is available at the pin REF.
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This approach allows avoiding more expensive sensing devices
while achieving the required accuracy for DC and AC measurements
of current and voltage, as well as stability over the operating
temperature range of the inverter.
12-Bit 100 kSPS ADCs for accurate voltage and current
measurement
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Power inverters in solar photovoltaic systems are often connected
directly to the electricity grid in order to inject the created energy into
the mains and act as an electricity supplier. This energy must comply
with certain regulations that set the standard in terms of quality and
safety which requires of accurate measurements.
2 Key Features
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1 General Description
The 12-bit ADC samples the voltage and current and provides their
instantaneous values through an SPI interface.
Low power on chip oscillator
The 12-bit ADC is preceded by low noise programmable gain
amplifiers in order to accommodate different sensors.
Internal registers for easy offset and gain compensation
The ADC has three multiplexed inputs, offering one secondary
channel in addition to the main voltage and current.
The on-chip temperature sensor provides the inverter designer the
option of temperature compensation for any of the measured
parameters or functional blocks provided, over the full operating
temperature range of the device.
The on-chip voltage reference is connected to the ADC and to REF.
An external crystal oscillator is not required as a high accuracy
internal oscillator clock is available.
SPI compatible interface
Interrupt alerts (including Under Voltage Lock-Out and Over
Temperature)
Independent programmable over current interrupt
3 Applications
The AS8002 is suitable for PV inverter grid monitoring, Wind inverter
grid monitoring, Isolated voltage sensing, Uninterruptible Power
supplies and Power conditioners.
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The independent over current interrupt detects a high current on the
grid and allows the processor to open the switches without waiting
for the ADC conversion.
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Revision 1.1
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AS8002
Data Sheet - A p p l i c a t i o n s
Curr
IOP_VOP
IOM_VOM
DVDD
REF
AS8002
V1M
V2P
V2M
12-Bit
ADC
Volt
V1P
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OSC
REF
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AVDD
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Figure 1. AS8002 Block Diagram
CAL
SCSB
CTRL
SCLK
UVLO
I/F
TEMP
OV TEMP
SDO
XINT
AVSS
DVSS
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OVER
CURR
SDI
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Revision 1.1
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AS8002
Data Sheet - C o n t e n t s
Contents
1
2 Key Features.............................................................................................................................................................................
1
3 Applications...............................................................................................................................................................................
1
4 Pin Assignments .......................................................................................................................................................................
4
4.1 Pin Descriptions....................................................................................................................................................................................
4
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1 General Description ..................................................................................................................................................................
5
6 Electrical Characteristics...........................................................................................................................................................
6
6.1 Operating Conditions............................................................................................................................................................................
6
6.2 Block Electrical Characteristics ............................................................................................................................................................
6
7 Detailed Description..................................................................................................................................................................
9
7.1 Operating Modes ................................................................................................................................................................................
10
7.2 SPI Interface.......................................................................................................................................................................................
10
7.3 SPI Interface Data Transfer Protocol..................................................................................................................................................
10
7.4
11
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5 Absolute Maximum Ratings ......................................................................................................................................................
SPI Hardware Connection ..............................................................................................................................................................
7.5 SPI Timing ..........................................................................................................................................................................................
12
7.6
13
Measurement Example ...................................................................................................................................................................
7.7
Measurement Control and Calibration ............................................................................................................................................
14
7.8
Interrupts.........................................................................................................................................................................................
14
7.9 Register Map Table.............................................................................................................................................................................
15
7.10 Register Description .........................................................................................................................................................................
16
8 Application Information ...........................................................................................................................................................
21
8.1 Application Hints.................................................................................................................................................................................
21
22
10 Ordering Information.............................................................................................................................................................
24
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9 Package Drawings and Markings ...........................................................................................................................................
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AS8002
Data Sheet - P i n A s s i g n m e n t s
4 Pin Assignments
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SCL
SCSB
DVDD
AVDD
Figure 2. Pin Assignments (Top View)
SDI
IOP_VOP
AS8002
QFN16
4x4x0.9
V1P
SDO
XINT
DVSS
AVSS
REF
V2M
V2P
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V1M
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IOM_VOM
4.1 Pin Descriptions
Table 1. Pin Descriptions
Pin Name
IOP_VOP
IOM_VOM
V1P
V1M
V2P
REF
Analog pin
Analog Input Channel 0. Positive input of the differential analog input.
2
Analog pin
Analog Input Channel 0. Negative input of the differential analog input.
3
Analog pin
Analog Input Channel 1. Positive input of the differential analog input.
4
Analog pin
Analog Input Channel 1. Negative input of the differential analog input.
5
Analog pin
Analog Input Channel 2. Positive input of the differential analog input.
6
Analog pin
Analog Input Channel 2. Negative input of the differential analog input.
7
Analog pin
Reference Positive Input Voltage.
8
Supply pin
Ground reference for the analog circuitry.
Supply pin
Ground reference for the digital circuitry.
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XINT
1
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AVSS
DVSS
Pin Type
ca
V2M
Pin Number
9
10
Description
Digital input/output Interrupt pin, active low
pin
11
Digital output pin
Serial peripheral interface (SPI): Serial Data Output
SDI
12
Digital input pin
Serial peripheral interface (SPI): Serial Data input
SCLK
13
Digital input pin
Serial peripheral interface (SPI): Serial Clock
SCSB
14
Digital input pin
Serial peripheral interface (SPI): Serial Chip Select (active low)
DVDD
15
Supply pin
Digital positive supply
AVDD
16
Supply pin
Analog positive supply
AVSS
PAD
Supply pin
Ground reference for the analog circuitry.
Te
SDO
Note: Pin number assignment is likely to change.
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AS8002
Data Sheet - A b s o l u t e M a x i m u m R a t i n g s
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 Block Electrical Characteristics on page 6 is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
Parameter
Min
Max
Units
Comments
DC supply voltage (VDD)
-0.3
+5.0
V
AVDD, DVDD
Input pin voltage (VIN)
-0.3
VDD+0.3
V
Electrostatic discharge (ESD)
-1000
1000
V
Storage temperature (Tstrg)
-55
125
ºC
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Table 2. Absolute Maximum Ratings
Norm: MIL 883 E method 3015
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The reflow peak soldering temperature (body
temperature) specified is in accordance with IPC/
JEDEC J-STD-020 “Moisture/Reflow Sensitivity
Classification for Non-Hermetic Solid State Surface
Mount Devices”.
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Lead temperature profile (Tbody)
5
85
%
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Humidity non-condensing
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AS8002
Data Sheet - E l e c t r i c a l C h a r a c t e r i s t i c s
6 Electrical Characteristics
6.1 Operating Conditions
Table 3. Operating Conditions
Conditions
Min
Typ
Max
Units
3.3
3.6
V
0
V
0.1
V
3.6
V
0
V
AVDD
Positive analog supply voltage
3.0
AVSS
Negative analog supply voltage
0
A-D
Difference of supplies
DVDD
Positive digital supply voltage
3.0
DVSS
Negative digital supply voltage
0
TAMB
Ambient temperature
-40
ISUPP
Supply current
-0.1
3.3
25
125
ºC
5
mA
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AVDD – DVDD
AVSS – DVSS
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Parameter
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Symbol
6.2 Block Electrical Characteristics
AVDD=3.0V to 3.6V, TAMB= -40 to +125ºC. Typical values at TAMB= +25ºC and AVDD=3.3V (unless otherwise specified).
Table 4. Block Electrical Characteristics
Symbol
Parameter
ADC DC Accuracy
Conditions
Min
Typ
Max
Units
12
Bits
-0.99
+0.99
LSB
-0.99
+0.99
LSB
±4
LSB
Resolution
RES
INL
Integral Nonlinearity
DNL
Differential Nonlinearity
OFS
Offset Error
±0.6
OFSM
Offset Error Match
±0.1
GAIN
Gain Error
Guaranteed No Missed Codes to 12 Bits
±4
Gain Error Match
GAINM
LSB
LSB
±0.1
LSB
71
dB
72
dB
-78
dB
84
dB
fIN = 40kHz
-79
dB
at 3dB
35
at 0.1dB
3.6
ADC Dynamic Specifications fIN=10 kHz Sine Wave Input
Signal to Noise = Distortion Ratio
SNR
Signal-to-Noise Ratio
THD
Total Harmonic Distortion
SFDR
Spurious-Free Dynamic Range
CCISOL
Channel-to-Channel Isolation
Full Power Bandwidth
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FLBW
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FPBW
ca
SINAD
fIN = 10kHz
MHz
ADC Analog Inputs of the Analog-to-Digital Converter
Differential Input Voltage Ranges
-VREF
VREF
V
VCMIN
Input Common Mode Voltage
VREF/2
VDDVREF/2
V
AILEAK
DC Leakage Current
-1
+1
µA
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VX+ – VX-
AIIZT
AIIZH
Input Capacitance
Track mode
TBD
pF
Hold mode
TBD
pF
ADC Conversion Rate
tCONV
Conversion Time
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Running from the internal oscillator
Revision 1.1
10
µs
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AS8002
Data Sheet - E l e c t r i c a l C h a r a c t e r i s t i c s
Table 4. Block Electrical Characteristics
Symbol
Parameter
Conditions
Min
Typ
tACQUISITION
Track-and-Hold Acquisition Time
TPUT
Throughput Rate
APERTURE
Aperture Delay
4
ns
JITTER
Aperture Jitter
50
ps
RFTC
Internal Reference Drift
TBD
µs
KSPS
Typical accuracy ±TBD%
2.5
10
Programmable Gain Amplifiers
Programmable
| VV0_I0 |
Input level 0
Differential, with gain of 64
AMPGAIN1
Gain channel 1
Programmable
| VV1 |
Input level 1
Differential, with gain of 6
2
2
ppm/ºC
64
V/V
14
20
mVP
c
8
V/V
150
212
mVP
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Gain channel 0
V
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AMPGAIN0
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Range
Units
100
Reference Output
RFRNG
Max
AMPOFFED
Offset error drift
-20
20
µV
AMPGAINED
Gain error drift
-0.1
0.1
%
AMPTHD
Total harmonic distortion
Temperature Sensor
TBD
TEMPAERR
Absolute Error (trimmed)
-5
+5
ºC
TEMPRERR
Relative Error (trimmed)
-3
+3
ºC
TEMPRNG
Temperature Range
-40
85
ºC
TEMPRES
Resolution
0.75
ºC/LSB
Frequency
10
MHz
Internal Oscillator
OSCFREQ
Relative Error
OSCERROR
Over Current
OVCURRDE
LAY
OVCURRER
ROR
Relative Error
UVLOHYST
%
2
µs
-20
+20
For threshold higher than 50mV
-10
+10
%
High Threshold
2.85
V
Hysteresis
0.1
V
VIH
Input High Voltage
VIL
Input Low Voltage
IIN
Input Current
CIN
Input Capacitance
Te
+10
For threshold lower than 50mV
ch
Digital Inputs
From chip input to output
ni
Under Voltage Lock Out
UVLOHI
ca
Reaction Time
-10
0.7xDVD
D
VIN=0V or DVDD
V
-1
0.3xDVD
D
V
+1
µA
15
pF
Digital Outputs
VOH
Output High Voltage
ISOURCE = 200 µA; DVDD = 3 to 3.6V
VOL
Output Low Voltage
ISINK = 200 µA
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DVDD 0.2
V
0.4
V
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AS8002
Data Sheet - E l e c t r i c a l C h a r a c t e r i s t i c s
Table 4. Block Electrical Characteristics
Symbol
Parameter
Coding
Output Coding
Conditions
Min
Typ
Max
Units
3.6
V
Two’s
complem
ent
Positive Supply Voltage
VDD
3
AVDD= 3V, fSAMPLE = 100ksps
Input amplifier OFF
AVDD = 3V, fSAMPLE = 100ksps
Input amplifier ON
IDD
µA
5
mA
1
µA
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Full shutdown mode (Off mode)
650
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Power Requirements
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AS8002
Data Sheet - D e t a i l e d D e s c r i p t i o n
7 Detailed Description
Figure 3 presents a typical application schematic for the AS8002 used for voltage and current measurement of a device connected to the grid
such a solar inverter or microinverter.
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The external circuitry comprises the power supply unit that is connected to the grid signal and that generates a stable DC voltage which is the
supply of the AS8002 and the digital isolation. Both current and voltage are scaled down and filtered prior to be sensed by the AS8002. In the
case of the voltage, a resistor divider is enough to scale down the voltage. In the case of the current, a low ohmic shunt resistor should be used.
The value of this shunt resistor should be calculated in order not to saturate the inputs of the AS8002 but to provide a good signal to noise ratio.
It is also important to minimize the value of the shunt resistor to lower the losses and increase the overall efficiency.
lv
Unlike commonly used sensing methods, the AS8002 is connected to the same potential level as the grid, which allows using a low cost shunt
resistor as the sensing device. The isolation is achieved by means of a digital isolator which should be able to handle a data rate of up to 2Mbps.
This sensing solution has several advantages compared to other common solutions, like the stability over temperature, accuracy of the
measurements and allowed bandwidth. All these lead to an accurate control of the DC-AC converter with low DC injection currents.
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Figure 3. Typical Application Circuit
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AS8002
Data Sheet - D e t a i l e d D e s c r i p t i o n
7.1 Operating Modes
When the supply voltage is below the threshold VPOR, the AS8002 is in Reset mode. Once the supply voltage is higher than VPOR, the AS8002
goes into Off mode during its initialization time tINIT. In this mode, the current consumption is reduced and only the Control register can be read
or written. Once the register bit chip_en has been set to 1, the chip goes into On mode and can be normally used after tWAKEUP. The chip can
go immediately back to Off mode by setting chip_en to 0.
Table 5. Characteristics
Description
Min
VPOR
POR threshold voltage
2.6
tINIT
Initialization time
3
tWAKEUP
Wake up time
300
Unit
V
ms
µs
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7.2 SPI Interface
Max
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Parameter
The 16-bit SPI interface enables read / write access to the register blocks and is compatible to a standard micro controller interface, using SPI
Mode 3 (SCLK initial state = high, data latched with rising edge of SCLK).
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The SPI module is active as soon as pin SCSB is pulled low. The AS8002 is then ready to read the 8-bit SPI address on the SDI input with every
rising edge of SCLK and writes on its SDO output with the falling edge of SCLK. After 16 clock cycles SCSB has to be set back to high status in
order to reset the interface for the next read/write cycle.
th
The address is split into an upper 7 bit address (addr[0…6]) and a lower 8 bit (R/W) containing the read/write information.
Writing data to the AS8002 is established by setting the R/W bit to 0. The 8 bits following this bit on SDI contain the data to be written into the
address specified in the first 8 bits.
Reading data is established by setting the R/W bit to 1. The 8 bits following this bit on SDO contain the data from the address specified in the first
8 bits on SDI.
Figure 4. Write Mode
SCSB
SCLK
ca
7.3 SPI Interface Data Transfer Protocol
addr[6:0]
6
5
4
3
ni
SDI
2
1
R/W
0
data[7:0]
7
6
5
7
6
5
4
3
2
2
1
0
1
0
4
3
2
1
0
Te
ch
SDO
5
3
read_meas_LSB[7:0]
read_meas_MSB[7:0]
6
4
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AS8002
Data Sheet - D e t a i l e d D e s c r i p t i o n
Figure 5. Read Mode
SCLK
addr[6:0]
5
4
6
5
3
2
1
0
data_addr[7:0]
read_meas_MSB[7:0]
3
2
1
0
7
6
5
4
3
2
1
0
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SDO
4
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6
SDI
R/W
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SCSB
The interface of the AS8002 corresponds to a 4-wire SPI where each data transfer is composed of 16 bits. Each 16-bit transfer of the SDI is
divided into a 7-bit address word indicating the target register, one R/W bit indicating the operation to be done and a 8-bit word data indicating
the data to be written.
The data transferred in SDO is also composed of 16 bits. These can be divided into the 8 MSBs which correspond to the 8 MSBs of the last
conversion run by the ADC plus 8 LSBs which clock out the data that has been requested by the SDI in that same cycle. This allows for a given
read register to be addressed and read in the same 16-bit transfer.
7.4 SPI Hardware Connection
Figure 6 shows a basic interconnection diagram of an AS8002 device with a host controller. Data transmission is enabled with signal SCSB (SS/
), the serial clock is applied at pin SCLK (SCK). Data is shifted into the AS8002 via signal SDI (MOSI) and read from the AS8002 via signal SDO
(MISO).
SDI
MISO
SDO
SCK
SCLK
SS/
SCSB
UC
Te
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MOSI
AS8002
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Figure 6. AS8002 and the Controller
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AS8002
Data Sheet - D e t a i l e d D e s c r i p t i o n
7.5 SPI Timing
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Figure 7. Timing Diagram
tXSSH
SCSB
(Input)
tsclk
tsclkL
tsclkH
tH
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tL
SCLK
(Input)
SDO
(Output)
tOZ
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tSDO
data[15]
data[14]
data[0]
tOZ
tSDI
SDI
(Input)
data[15]
data[14]
data[0]
Parameter
tL
tSCLKL
tSCLKH
Description
Min
Max
Unit
Time between SCSB falling edge and SCK rising edge
350
ns
Serial clock period
100
ns
Low period of serial clock
50
ns
ni
tSCLK
ca
Table 6. Timing Characteristics
50
ns
tH
tSCK / 2
ns
tXSSH
High time of SCSB between two transmissions
350
ns
tSDI
Data input valid to rising clock edge
20
ns
tSDO
SCLK falling edge to data output valid
Te
ch
High period of serial clock
Time between last falling edge of SCK and rising edge
of SCSB
20
ns
Note: The data on SDO initially reflects the data corresponding to the previous command on SDI. Hence, in write mode, the full 16-bit data of
a measurement can be read.
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AS8002
Data Sheet - D e t a i l e d D e s c r i p t i o n
7.6 Measurement Example
The following example shows a simple way to alternately read the voltage and current values:
Bits [b2:b0] in Addr 03h control the ADC input multiplexer:
Addr
Default
Input Multiplexer
03h
00h
Content
b7
b6
b5
b4
b3
b2
b1
b0
mux_sel[2:0]
0: Current channel PGA output
1: Voltage channel PGA output
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Name
adc_en
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1. Select the Current channel input (IOM, IOP) : 0610h
- Set the Address [A6:A0] to 03h,
- Set the R/W bit to 0 (write mode) and the data to 10h (adc_en = 1, mux_sel = 0)
- In parallel to writing the 16-bit data on SDI, a set of 16-bit data can be read on SDO, which contains the data from the second to last
command.
2. Select the Voltage channel input (V1M, V1P) : 0611h
- Set the Address [A6:A0] to 03h,
- Set the R/W bit to 0 (write mode) and the data to 11h (adc_en = 1, mux_sel = 1)
- In parallel to writing the 16-bit data on SDI, a set of 16-bit data can be read on SDO, which contains the data from the second to last
command.
3. Change the input multiplexer back to Current channel input (IOM, IOP) : 0610h
- Repeat the sequence 1 above: addr = 03h, data = 10h,
- The 16-bit current input data from the second to last invoked command (1 above) can be read on SDO.
4. Loop sequences 2 and 3
Note: In sequence 2, the 16-bit voltage input data from the second to last command can be read on SDO.
Figure 8. Measurement Diagram
1)
MSB
2)
0610h
LSB
MSB
0611h
3)
LSB
MSB
0610h
4)=2)
LSB
MSB
0611h
set Mux to
Current
measurement
set Mux to
Voltage
measurement
set Mux to
Current
measurement
set Mux to
Voltage
measurement
SDO
data from
previous
command
data from
previous
command
read Current
input value
read Voltage
input value
ni
ca
SDI
LSB
ch
MSB
LSB
Transmission 2
MSB
LSB
Transmission 3
MSB
LSB
Transmission 4
Te
Transmission 1
MSB
LSB
Note: The 16-bit input data from the voltage and current measurements contain the ADC data in the lower 12 bits and two status bits in the
upper 4 bits (see Register Map Table on page 15).
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AS8002
Data Sheet - D e t a i l e d D e s c r i p t i o n
Table 7. Current and Voltage Measurements
Content
Name
b14
b13
b12
b11:b0
Current Measurement
0
warning_detected
interrupt_detected
X
curr_meas
Voltage Measurement
0
warning_detected
interrupt_detected
X
volt_meas
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b15
7.7 Measurement Control and Calibration
The conversion starts on SCSB falling edge when adc_en is a 1. The value of the result of the conversion can be read at the next SPI write
command 10µs later.
channel measured
channel read
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SCSB
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Figure 9. ADC Burst Mode
Not updated
channel_1
Not updated
channel_2
channel_3
channel_1
channel_2
Read_meas will be transferred to the Current, Voltage or Auxiliary measurement upon mux_sel[2:0] value – curr_meas, volt_meas or
aux_meas.
Calibration is done according to the formulas:
For voltage channel:
(EQ 1)
read_meas = adc_meas * (1024 + pga_volt_gain_cal) / 1024
(EQ 2)
ni
For auxiliary channel:
read_meas = adc_meas * (1024 + pga_curr_gain_cal) / 1024
ca
For current channel:
read_meas = adc_meas * (1024 + aux_gain_cal) / 1024
(EQ 3)
ch
Note: The Raw ADC results are also available in the registers and are called adc_meas[11:0]
7.8 Interrupts
When an over current, an under voltage or an over temperature occurs the bit warning_detected is set to 1.
Te
The interrupt state is present on interrupt_detected and on the pin XINT.
The statuses are available in the register Interrupt Status. It contains the bits over_currrent_int_en, under_voltage_int_en,
over_temp_int_en.
The generation of the interrupt can be enabled or disabled in the register “Interrupt Enable”. It contains the bits over_currrent_int_i,
under_voltage_int_i, over_temp_int_i.
Values of the register Interrupt Status are kept until this register is read.
www.austriamicrosystems.com/AS8002
Revision 1.1
14 - 24
AS8002
Data Sheet - D e t a i l e d D e s c r i p t i o n
7.9 Register Map Table
Table 8. Register Map
Content
Name
Addr
Default
Control
01h
00h
PGA Gain
02h
00h
Input Multiplexer
03h
00h
adc_en
Over Temperature
Threshold
04h
FFh
over_temp_thres[7:0]
Interrupt Enable
05h
00h
Over Current Range
06h
FFh
Current Measurement
MSB
10h
00h
Current Measurement
LSB
11h
00h
Voltage Measurement
MSB
12h
00h
Voltage Measurement
LSB
13h
00h
Auxiliary
Measurement MSB
14h
00h
Auxiliary
Measurement MSB
15h
00h
aux_meas[7:0]
Temperature
Measurement
16h
00h
temp[7:0]
Interrupt Status
17h
00h
b5
b4
b3
b2
b1
b0
over_
current_ch
annel
over_
current_
en
adc_ref_
en
pga_
volt_en
pga_
curr_en
temp_
sensor_
en
chip_en
pga_volt_gain[1:0]
pga_curr_gain[4:0]
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b6
mux_sel[2:0]
lv
b7
over_
current_int
_en
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over_current_range[7:0]
under_
voltage_
int_en
0
warning_
detected
interrupt_
detected
X
over_
temp_int_
en
curr_meas[11:8]
curr_meas[7:0]
0
warning_
detected
interrupt_
detected
X
volt_meas[11:8]
volt_meas[7:0]
ca
0
warning_
detected
interrupt_
detected
X
aux_meas[11:8]
over_
current_i
under_
voltage_i
over_
temp_i
18h
02h
0
0
0
0
0
0
1
0
19h
5Xh
0
1
0
1
X
X
X
X
1Ah
00h
0
warning_
detected
interrupt_
detected
X
Raw ADC Results
LSB
1Bh
00h
adc_meas[7:0]
PGA Current Gain
Calibration
3Ah
00h
pga_curr_gain_cal[7:0]
PGA Voltage Gain
Calibration
3Bh
00h
pga_volt_gain_cal[7:0]
Auxiliary Channel
Gain Calibration
3Ch
00h
aux_gain_cal[7:0]
ASIC ID 1
ASIC ID 2
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Raw ADC Results
MSB
adc_meas[11:8]
Note: Highlighted registers are Read only registers (bits).
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Revision 1.1
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AS8002
Data Sheet - D e t a i l e d D e s c r i p t i o n
7.10 Register Description
Table 9. 01h
Control Register
Address:
01h
Controls the power on and off of the internal blocks
Bit Name
Default
Access
0
chip_en
0h
R/W
0: Chip in complete power off
1: Chip on
1
temp_sensor_en
0h
R/W
0: Temperature sensor disabled
1: Temperature sensor enabled
2
pga_curr_en
0h
R/W
0: Current channel PGA disabled
1: Current channel PGA enabled
3
pga_volt_en
0h
R/W
0: Voltage channel PGA disabled
1: Voltage channel PGA enabled
4
adcref_en
0h
R/W
0: Internal ADC reference voltage off
1: Internal ADC reference voltage on
Note: This bit must be set to allow ADC measurements.
5
over_current_en
0h
R/W
0: Over current detector disabled
1: Over current detector enabled
6
over_current_channel
0h
R/W
0: Over current detector connected to inputs IOP_VOP and IOM_VOM
1: Over current detector connected to inputs V2P and V2M
Address:
02h
PGA Gain Register
Controls the gain of the current and voltage channel PGAs
Bit Name
Default
Access
4:0
pga_curr_gain
00h
R/W
7:6
pga_volt_gain
0h
R/W
Address:
03h
Default
ni
Bit Name
4
Gain for current channel is given by the formula:
2*pga_curr_gain+2
(EQ 4)
Gain for voltage channel is given by the formula:
2*pga_volt_gain+2
(EQ 5)
Input Multiplexer Register
Controls the ADC and select the channel to be converted
Access
Description
mux_sel
00h
R/W
adc_en
0h
R/W
Enable the ADC conversion that will start on the next SCSB falling edge
Te
2:0
Description
Select the input to be converted:
0: Current channel PGA output
1: Voltage channel PGA output
2: V2P and V2M
3: AVDD and AVSS
4: IOP_VOP and IOM_VOM
5: V1P and V1M
6: Reserved
7: Reserved
ch
Bit
ca
Bit
Table 11. 03h
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Table 10. 02h
Description
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Bit
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Revision 1.1
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AS8002
Data Sheet - D e t a i l e d D e s c r i p t i o n
Table 12. 04h
Over Temperature Threshold Register
Address:
04h
Set the over temperature threshold value
Bit Name
Default
Access
7:0
over_temp_thres
FFh
R/W
Description
Over temperature detection is triggered when temp value is higher than
over_temp_thres
Table 13. 05h
Interrupt Enable Register
Address:
05h
Separately enables the interrupts
Bit Name
Default
Access
0
over_temp_int_en
0h
R/W
0: Interrupt due to over temperature is disabled
1: Interrupt due to over temperature is enabled
1
under_voltage_int_en
0h
R/W
0: Interrupt due to under voltage is disabled
1: Interrupt due to under voltage is enabled
2
over_current_int_en
0h
R/W
0: Interrupt due to over current is disabled
1: Interrupt due to over current is enabled
Address:
06h
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Table 14. 06h
Description
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Bit
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Bit
Over Current Range Register
Set the over current comparators absolute threshold voltage
Bit
Bit Name
Default
Access
7:0
over_current_range
FFh
R/W
Description
The threshold voltage is given by the formula:
over_current_range*1m
(EQ 6)
Where: over_current_range should be higher than 10h
Table 15. 10h
Address:
10h
Current Measurement MSB Register
Gives measured value of current (MSB) and status of warnings and interrupts
Bit Name
3:0
curr_meas[11:8]
ni
interrupt detected
ch
5
warning detected
0h
0h
0h
Access
Description
R
MSB of current channel measurement, value is given as 2’s complement
number by the formula:
I=curr_meas*1.22m / (Rshunt*curr_gain)
R
Same value as XINT (complemented)
0: No interrupt detected
1: Interrupt is detected
R
Over temperature, under voltage or over current detected
0: No warning detected
1: Warning detected
(EQ 7)
Te
6
Default
ca
Bit
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Revision 1.1
17 - 24
AS8002
Data Sheet - D e t a i l e d D e s c r i p t i o n
Table 16. 11h
Current Measurement LSB Register
Address:
11h
Gives measured value of current (LSB)
Bit Name
Default
Access
7:0
curr_meas[7:0]
0h
R
Description
LSB of current channel measurement, value is given as 2’s complement
number by the formula:
I=curr_meas*1.22m / (Rshunt*curr_gain)
Table 17. 12h
Voltage Measurement MSB Register
Address:
12h
(EQ 8)
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Bit
lv
Gives measured value of voltage (MSB) and status of warnings and interrupts
Bit
Bit Name
Default
Access
Description
3:0
volt_meas[11:8]
0h
R
MSB of voltage channel measurement, value is given as 2’s complement
number by the formula:
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volt_meas*1.22m / volt_gain
5
interrupt detected
0h
R
Same value as XINT (complemented)
0: No interrupt detected
1: Interrupt is detected
6
warning detected
0h
R
Over temperature, under voltage or over voltage detected
0: No warning detected
1: Warning detected
Table 18. 13h
Address:
13h
(EQ 9)
Voltage Measurement LSB Register
Gives measured value of voltage (LSB)
Bit
Bit Name
Default
Access
Description
7:0
volt_meas[7:0]
0h
R
LSB of voltage channel measurement, value is given as 2’s complement
number by the formula:
Table 19. 14h
Address:
14h
Default
Access
Description
aux_meas[11:8]
0h
R
MSB of auxiliary channel measurement, value is given as 2’s complement
number by the formula:
interrupt detected
Te
5
6
Auxiliary Measurement MSB Register
Bit Name
ch
3:0
(EQ 10)
Gives measured value of auxiliary channel (MSB) and status of warnings and interrupts
ni
Bit
ca
volt_meas*1.22m / volt_gain
warning detected
www.austriamicrosystems.com/AS8002
aux_meas*1.22m
0h
R
Same value as XINT (complemented)
0: No interrupt detected
1: Interrupt is detected
0h
R
Over temperature, under auxiliary or over auxiliary detected
0: No warning detected
1: Warning detected
Revision 1.1
(EQ 11)
18 - 24
AS8002
Data Sheet - D e t a i l e d D e s c r i p t i o n
Table 20. 15h
Auxiliary Measurement LSB Register
Address:
15h
Gives measured value of auxiliary channel (LSB)
Bit
Bit Name
Default
Access
Description
7:0
aux_meas[7:0]
0h
R
LSB of auxiliary channel measurement, value is given as 2’s complement
number by the formula:
Table 21. 16h
Temperature Measurement Register
Address:
16h
Bit Name
Default
Access
7:0
temp
0h
R
Table 22. 17h
Address:
17h
Bit
Description
Temperature value (in °C) is given by the formula:
92+temp*3/4
Interrupt Status Register
Gives status of each interrupt source
Bit Name
Default
Access
Description
0
over_temp_i
0h
R
0: over temperature not detected
1: over temperature detected
1
under_voltage_i
0h
R
0: under voltage not detected
1: under voltage detected
2
over_current_i
0h
R
0: over current not detected
1: over current detected
Table 23. 18h
Address:
18h
ASIC ID 1 Register
Provides Chip identification
Bit Name
7:0
asic_id
R
Description
Chip indentification
ASIC ID 2 Register
Provides chip version number
Default
Access
asic_version
5Xh
R
Description
50h: Chip version 0
51h: Chip version 1
Te
7:0
Access
Bit Name
ch
Bit
02h
ni
Address:
19h
Default
ca
Bit
Table 24. 19h
(EQ 13)
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Gives measured value of temperature
(EQ 12)
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aux_meas*1.22m
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Revision 1.1
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AS8002
Data Sheet - D e t a i l e d D e s c r i p t i o n
Table 25. 1Ah
Raw ADC Results MSB Register
Address:
1Ah
Gives measured value of the ADC (MSB) and status of warnings and interrupts
Bit Name
Default
Access
3:0
adc_meas[11:8]
0h
R
Description
MSB of raw ADC measurement, value is given as 2’s complement
number by the formula:
adc_meas*1.22m
interrupt detected
0h
R
Same value as XINT (complemented)
0: No interrupt detected
1: Interrupt is detected
6
warning detected
0h
R
Over temperature, under voltage or over current detected
0: No warning detected
1: Warning detected
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5
Bit
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Table 26. 1Bh
Address:
1Bh
Raw ADC Results LSB Register
Gives measured value of raw ADC (LSB)
Bit Name
7:0
Default
adc_meas[7:0]
0h
Access
Description
R
LSB of raw ADC measurement, value is given as 2’s complement number
by the formula:
adc_meas*1.22m
Table 27. 3Ah
Address:
3Ah
Set value of correction coefficient for current measurement
Bit Name
Default
Access
7:0
pga_curr_gain_cal
00h
R/W
Description
Correct the measured current value multiplying it by the following factor,
where pga_curr_gain_cal is a number defined as 2’s complement:
Set value of correction coefficient for voltage measurement
Default
Access
pga_volt_gain_cal
00h
R/W
Description
Correct the measured voltage value multiplying it by the following factor,
where pga_volt_gain_cal is a number defined as 2’s complement:
(1024 + pga_volt_gain_cal) / 1024
ch
7:0
(EQ 16)
PGA Voltage Gain Calibration Register
Bit Name
ni
Bit
ca
(1024 + pga_curr_gain_cal) / 1024
Address:
3Bh
(EQ 15)
PGA Current Gain Calibration Register
Bit
Table 28. 3Bh
(EQ 14)
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Bit
(EQ 17)
Table 29. 3Ch
Auxiliary Channel Gain Calibration Register
Te
Address:
3Ch
Bit
7:0
Bit Name
aux_gain_cal
Set value of correction coefficient for auxiliary measurement
Default
00h
Access
R/W
Description
Correct the measured value of the auxiliary channel multiplying it by the
following factor, where aux_gain_cal is a number defined as 2’s
complement:
(1024 + aux_gain_cal) / 1024
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Revision 1.1
(EQ 18)
20 - 24
AS8002
Data Sheet - A p p l i c a t i o n I n f o r m a t i o n
8 Application Information
Table 30 provides examples of Gain selection of Channel 1 for different shunt resistors and maximum RMS currents.
Table 30. Gain Selection
Sensing RMS Current (A)
Recommended Linear Gain for Channel 1 for
ADC to work in 80% of dynamic range
7.5 mΩ
1.5
Gain1 = 64
10 mΩ
1.5
Gain1 = 48
5 mΩ
3
Gain1 = 48
7.5 mΩ
3
Gain1 = 32
10 mΩ
3
Gain1 = 24
5 mΩ
6
7.5 mΩ
6
10 mΩ
6
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Shunt Resistor Value
Gain1 = 24
Gain1 = 16
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Gain1 = 12
8.1 Application Hints
Grounding and Layout. The analog and digital supplies of the AS8002 (AVDD, DVDD, AVSS, DVSS) are independent and separately
pinned out to minimize coupling between the analog and digital sections of the device. The printed circuit board (PCB) that houses the AS8002
should be designed such that the analog and digital sections are separated and confined to certain areas on the board. This design facilitates the
use of ground planes that can be easily separated.
To provide optimum shielding for ground planes, a minimum etch technique is generally best. All VSS pins of the AS8002 should be sunk in the
ground plane. Digital and analog ground planes should be joined in only one spot. If the AS8002 is in a system where multiple devices require an
AVSS and DVSS connection, this connection should still be made at one point only; a star ground point that should be established as close as
possible to the ground pins on the AS8002.
Avoid running digital lines under the device as this couples noise into the chip. However, the analog ground plane should be allowed to run under
the AS8002 to avoid noise coupling. The power supply lines to the AS8002 should use as large trace width as possible to provide low impedance
paths and reduce the effects of glitches on the power supply line.
Likewise, the positive supply pins AVDD and DVDD should be connected only at one common star point close the output of the power supply.
For best performance of the analog blocks of the AS8002, it is important to have a clean, noise-free supply voltage at AVDD.
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To avoid radiating noise to other sections of the board, fast switching signals, such as clocks, should be shielded with digital ground, and clock
signals should never run near the analog inputs. Avoid crossover of digital and analog signals. To reduce the effects of feedthrough within the
board, traces on opposite sides of the board should run at right angles to each other. A microstrip technique is the best method but is not always
possible with a double sided board. In this technique, the component side of the board is dedicated to ground planes, while signals are placed on
the opposite side.
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Good decoupling is also important. All analog supplies should be decoupled with 10µF ceramic capacitors in parallel with 0.1µF capacitors to
GND. Refer to Typical Application Circuit (page 9). To achieve the best results from these decoupling components, they must be placed as close
as possible to the device The 0.1µF capacitors should have low effective series resistance (ESR) and low effective series inductance (ESI), such
as common ceramic types or surface-mount types. These low ESR and ESI capacitors provide a low impedance path to ground at high
frequencies to handle transient currents due to internal logic switching.
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Revision 1.1
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AS8002
Data Sheet - P a c k a g e D r a w i n g s a n d M a r k i n g s
9 Package Drawings and Markings
The device is available in a 16-pin QFN (4x4x0.9mm) package.
5
6
7
8
9
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Figure 10. 16-pin QFN (4x4x0.9mm) Package
3
10
11
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2
#1
12
Typ
0.85
0.203 REF
0.30
4.00 BSC
4.00 BSC
2.40
2.40
ni
Min
0.75
0.25
ch
Symbol
A
A1
b
D
E
D2
E2
ca
16
0.35
2.50
2.50
Symbol
e
L
L1
P
aaa
ccc
Min
0.40
14
13
Typ
0.65 BSC
0.50
Max
0.60
0.10
45º BSC
0.15
0.10
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2.30
2.30
Max
0.95
15
Notes:
1. Dimensioning and tolerancing conform to ASME Y14.5M-1994.
2. All dimensions are in millimeters, angles are in degrees.
3. Dimension b applies to metallized terminal and is measured between 0.25 and 0.30mm from terminal tip. Dimension L1 represents
terminal full back from package edge up to 0.1mm is acceptable.
4. Coplanarity applies to the exposed heat slug as well as the terminal.
5. Radius on terminal is optional.
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Revision 1.1
22 - 24
AS8002
Data Sheet - R e v i s i o n H i s t o r y
Revision History
Revision
Date
Owner
Description
1.0
14 May, 2010
jja
Initial revision
25 Aug, 2010
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Note: Typos may not be explicitly mentioned under revision history.
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1.1
Updated the following in Register Map (page 15):
1) Register bit b4 at address 01 (previously under_voltage_en) is now
adc_ref_en
2) ASIC ID 2 register value is now 5Xh
www.austriamicrosystems.com/AS8002
Revision 1.1
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AS8002
Data Sheet - O r d e r i n g I n f o r m a t i o n
10 Ordering Information
The devices are available as the standard products shown in Table 31.
Table 31. Ordering Information
Description
Delivery Form
Package
AS8002 AQFP
Temperature: -40ºC to 125ºC
Tape & Reel in Dry Pack;
6000 pieces / reel
16-pin QFN (4x4x0.9mm)
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Ordering Code
Note: All products are RoHS compliant and Pb-free.
Buy our products or get free samples online at ICdirect: http://www.austriamicrosystems.com/ICdirect
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For further information and requests, please contact us mailto:sales@austriamicrosystems.com
or find your local distributor at http://www.austriamicrosystems.com/distributor
Copyrights
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Copyright © 1997-2010, austriamicrosystems AG, Tobelbaderstrasse 30, 8141 Unterpremstaetten, Austria-Europe. Trademarks Registered ®.
All rights reserved. The material herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of
the copyright owner.
All products and companies mentioned are trademarks or registered trademarks of their respective companies.
Disclaimer
Devices sold by austriamicrosystems AG are covered by the warranty and patent indemnification provisions appearing in its Term of Sale.
austriamicrosystems AG makes no warranty, express, statutory, implied, or by description regarding the information set forth herein or regarding
the freedom of the described devices from patent infringement. austriamicrosystems AG reserves the right to change specifications and prices at
any time and without notice. Therefore, prior to designing this product into a system, it is necessary to check with austriamicrosystems AG for
current information. This product is intended for use in normal commercial applications. Applications requiring extended temperature range,
unusual environmental requirements, or high reliability applications, such as military, medical life-support or life-sustaining equipment are
specifically not recommended without additional processing by austriamicrosystems AG for each application. For shipments of less than 100
parts the manufacturing flow might show deviations from the standard production flow, such as test flow or test location.
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The information furnished here by austriamicrosystems AG is believed to be correct and accurate. However, austriamicrosystems AG shall not
be liable to recipient or any third party for any damages, including but not limited to personal injury, property damage, loss of profits, loss of use,
interruption of business or indirect, special, incidental or consequential damages, of any kind, in connection with or arising out of the furnishing,
performance or use of the technical data herein. No obligation or liability to recipient or any third party shall arise or flow out of
austriamicrosystems AG rendering of technical or other services.
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Contact Information
Headquarters
Te
austriamicrosystems AG
Tobelbaderstrasse 30
A-8141 Unterpremstaetten, Austria
Tel: +43 (0) 3136 500 0
Fax: +43 (0) 3136 525 01
For Sales Offices, Distributors and Representatives, please visit:
http://www.austriamicrosystems.com/contact
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