[AK8998/W/D]
Preliminary
AK8998/W/D
The AK8998 is a pressure sensor interface IC that features compensation for temperature drift and sensor
variation. It is designed to excite and interface to a bridge sensor. Variations in the sensor can be
corrected via compensation values stored in integrated non-volatile memory (EEPROM). Compensation
values are obtained from measurement results for a set of offset voltages and temperature drift, along with
a set of bridge voltages and temperature drift, including characteristics of the AK8998. The AK8998 is
available in a 16-pin QFN package, in wafer form and in a tray.
Features
•
Pressure sensor compensation and excitation IC (Analog output)
•
Supply voltage current: 7.1mA max @10kHz sampling
•
Supply voltage: 3.0V±5%, 3.3V±5%, 5.0V±5%
•
Operating temperature range: -20 to 85ºC
•
Integrated sensor output compensation (AK8998 Input conversion)
•
Offset voltage adjustment
-
Adjustment range: Rough ±13 to ±373mV / Fine ±1 to ±34mV @5.0V
-
Adjustment step: Rough 2 to 53mV /step / Fine 0.01 to 0.27mV /step @5.0V
•
Offset voltage temperature drift adjustment (1st order coefficient)
-
Adjustment range: ±0.04 to ±1.23mV/ºC @5.0V
-
Adjustment step: 0.2 to 4.8µV/ºC @5.0V
•
Output span voltage adjustment (G1, G2, G3)
-
Total adjustment range:
5.7 to 261.6mV @5.0V
-
G1 adjustment step :
0.95 to 74.7mV /step @5.0V
-
G2 adjustment step :
5.7 to 130.8mV /step @5.0V
-
G3 adjustment step :
0.01 to 0.40mV /step @5.0V
•
Sensitivity temperature drift adjustment (1st order coefficient)
-
Adjustment range: -4000ppm/ºC to +2500ppm/ºC or -2500ppm/ºC to +1000ppm/ºC
-
Adjustment step: 18ppm/ºC step
•
Integrated output reference voltage adjustment function
-
Adjustment range: 0.02*VDD to 0.98*VDD
-
Adjustment step: 10mV /step @5.0V
•
Integrated sampling frequency switching function :
1kHz, 10kHz
•
Integrated analog circuit reference voltage stabilizer
(Add an external capacitor to AGND pin as needed)
•
SCF and SMF included for band limitation:
fc:1.0kHz, 500Hz, 250Hz
•
2 wire serial interface (CSCLK, VOUT)
•
Ratiometric voltage output
•
Integrated constant voltage source for pressure sensor: 2.2V @ 3.0, 3.3V±5%
4.0V or 2.2V @ 5.0V±5%
•
Integrated pressure detectors (x2)
-
Detection threshold adjustment control
-
Adjustment range: 0.125*VDD to 0.9*VDD
-
Adjustment step: 0.025*VDD /step
-
Detection threshold external setting function (DET2 / PTH pin use)
-
hysteresis voltage adjustment control
-
Adjustment range: 0.03*VDD to 0.06*VDD
-
Adjustment step: 0.01*VDD /step
•
Integrated reference voltage & reference current generator
-
VREF voltage adjustment control
-
Resolution: 3bits
-
Adjustment step: 1% /step
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[AK8998/W/D]
IREF current adjustment control
-
Resolution:
4bits
-
Adjustment step: 2.8% /step typ.
•
Temperature sensor (internal or external)
-
Temperature range: -20 to 85
°C
-
Internal temperature sensor output voltage adjustment control
-
Resolution:
6 bits
-
Adjustment step: 0.2% /step
-
External temperature sensor output voltage adjustment control
-
Resolution:
9 bits
（
Rough/ Fine=3/6bits）
）
-
Adjustment step: Rough 10% /step / Fine 0.2% /step
-
Integrated external temperature sensor constant current circuit: 50µA typ.
•
Integrated oscillator for intermittent operation (1000kHz typ.)
-
Oscillating frequency adjustment control
-
Resolution:
4 bits
-
Adjustment step: 5% /step typ.
•
Integrated EEPROM for compensation values and control data storage
-
Size:
131 bits
-
Endurance: 1,000 times or more
-
Retention time: 10 years or more @Ta: 85°C
•
Supply Type: Tray (Die), Wafer, PKG (UQFN16)
-
Product name
AK8998
AK8998W
AK8998D
Supply Type
PKG (UQFN16)
Wafer
Tray (Die)
Comments
Block Diagram
VDD
VS
Regulator
V_Bandgap
V_Reference
I_Reference
Gain Temp.
track
Offset Temp.
track
Oscillator
Timing
Logic
V_
Common
Power ON
Reset
VSS
AGND
VDD track
V_Temp.
EXTMP
(internal or
external)
STV
VOUT
EEPROM
Pressure Detector 2
Pressure Detector 1
DET2 / PTH
DET1
Offset_Temp.
VP
VN
Gain Amp.1
Gain Amp.2
Offset
Gain_Temp.
LPF
Gain Amp.3
Gain
EEPROM
&
Control
Register
Serial I/F SDI/O
S/H & SCF
& Level Shift
Buffer
& SMF
VO
VOUT
Gain Amplifier Block
CSCLK
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[AK8998/W/D]
Overview
The AK8998 is a pressure sensor interface IC that features compensation for temperature drift and sensor
variation.
It is designed to excite and interface to a bridge sensor. Variations in the sensor can be corrected via
compensation values stored in integrated non-volatile memory (EEPROM). Compensation values are
obtained from measurement results for a set of offset voltages and temperature drift, along with a set of
bridge voltages and temperature drift, including characteristics of the AK8998.
The internal compensation circuit is accomplished through a 12-bit resolution DAC (Rough: 4bits, Fine:
8bits) to adjust offset voltage, and the primary characteristics compensator for the associated temperature
drift, coupled with 13-bit resolution (G1&G2 Gain adjustment: 5bits, G3 Gain adjustment: 8bits) to adjust
the span voltage and another primary characteristics compensator for its associated temperature drift.
The output stage, with an internal resistor of 146kΩ, is band-limited with a combination of external
capacitors, providing a low impedance output. And the EEPROM data, if used, enables the internal SCF
and SMF. In this case, the band limitation is performed by the internal LPF (fc: 1kHz, 500Hz, 250Hz),
eliminating the need for the external capacitors.
EEPROM data can be preconfigured to enable a setup of output reference voltage, designation of the
external temperature sensor (when a pressure sensor and AK8998 are separated), selection of a
sampling frequency (1kHz or 10kHz), the input polarity, and AGND pin validation.
Two sets of the pressure detectors are provided. When the pressure exceeding the detection threshold
stored in the EEPROM is applied, the DET 1 and/or DET2/PTH pins go high (the polarity change is
possible by EEPROM). And the detection threshold can be specified externally by EEPROM. In that case,
the Pressure Detectors 2 is disabled, and the detection threshold for the Pressure Detectors 1 can be
defined by DET2/PTH pin.
It can access to the EEPROM and control register (volatile memory) by a two-wire serial interface of
CSCLK and VOUT (at the time of SDI/O mode) pin.
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[AK8998/W/D]
Pin Configuration
1. Wafer Configuration
1)
2)
3)
4)
5)
6)
Die size
Die thickness
PAD size
PAD pitch
Scribe size
Wafer size
2.082mm x 1.662mm
280µm
80µm x 80µm
150µm<
80µm
6 inch
Pin numbers and Pad position
No.
1
2
3
4
5
6
7
8
Pin Name
VSS
VO
VOUT
VDD
AGND
N.C.
N.C.
N.C.
X Location
(µm)
-894.8
-894.8
-894.8
-894.8
-521.7
Y Location
(µm)
687.2
337.8
-344.7
-687.1
-684.8
No.
9
10
11
12
13
14
15
16
Pin Name
CSCLK
DET1
DET2/PTH
N.C.
VN
VS
VP
EXTMP
X Location
(µm)
894.8
894.8
894.8
749.3
363.4
-236.7
-716.4
Y Location
(µm)
-544.7
-242.5
-57.9
684.8
684.8
684.8
684.8
Pad locations (Top view)
1
16
15
14
13
2
Y
X
(0,0)
3
11
10
4
5
9
2. Package Outline (UQFN16)
10 DET1
DET2
11 /PTH
12
N.C.
9 CSCLK
13
14
15
VN
VS
VP
8
7
6
5
1
VSS
2
3 VOUT
4
N.C.
N.C.
N.C.
AGND
16 EXTMP
VDD
VO
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[AK8998/W/D]
Adjustment Characteristics
1) Sensor Characteristics
■VDD: 5V
Item
Symbol
Drive voltage
Svs1
Svs2
Temperature range
Sta
Sensor resistance
Sres1
Sres2
Voltage input span
Sspnin1
range
Sspnin2
Offset voltage
Soff1
adjustment range
Soff2
Sensitivity temp. drift
Sst1
coefficient
Sst2
Offset temp. drift
Sot1
coefficient
Sot2
■VDD:3, 3.3V
Item
Drive voltage
Temperature range
Sensor resistance
Voltage input span
range
Offset voltage
adjustment range
Sensitivity temp. drift
coefficient
Offset temp. drift
coefficient
Min.
Typ.
2.2
4.0
4.00
4.00
44.00
70.00
0.00
0.00
Max.
-20
0.82
1.00
12.00
17.00
-15.00
-35.00
-4000
-2500
-0.040
-0.080
0.00
0.00
85
6.50
6.50
76.00
125.00
15.00
35.00
2500
1000
0.040
0.080
units
V
V
°C
kΩ
kΩ
mV
mV
mV
mV
ppm/°C
ppm/°C
mV/°C
mV/°C
Comments
EVD[1:0]=1h
EVD[1:0]=0h
EVD[1:0]=1h
EVD[1:0]=0h
Sensor1
Sensor2
Sensor1
Sensor2
ESTC[0]=1h
ESTC[0]=0h
Sensor1
Sensor2
Symbol
Min.
Typ.
Max.
units
Comments
Svs
2.2
V
Sta
-20
85
°C
Sres
0.82
4.00
6.50
kΩ
Sspnin1
6.60
24.20
41.80
mV
Sensor1
Sspnin2
9.00
40.00
70.00
mV
Sensor2
Soff1
-8.25
0.00
8.25
mV
Sensor1
Soff2
-19.25
0.00
19.25
mV
Sensor2
Sst1
-4000
2500
ppm/°C ESTC[0]=1h
Sst2
-2500
1000
ppm/°C ESTC[0]=0h
Sot1
-0.022
0.00
0.022
mV/°C Sensor1
Sot2
-0.044
0.00
0.044
mV/°C Sensor2
Note) The usage combines characteristics of senser 1/2 is not allowed. Such a case as Span voltage is
said as the sensor 1 and except is said as the sensor 2).
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Embedded System
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