IC-MQ_15 Datasheet, PDF (16/43 Pages) IC-Haus GmbH – Sin/Cos INTERPOLATION IC WITH RS422 DRIVER

iC-MQ PROGRAMMABLE 9-BIT
Sin/Cos INTERPOLATION IC WITH RS422 DRIVER
BIAS CURRENT SOURCE AND TEMPERATURE SENSOR CALIBRATION
Rev F3, Page 16/43
Bias Current
The calibration of the bias current source in operation
mode Calibration 1 (see Table 63) is prerequisite for
adherence to the given electrical characteristics and
also instrumental in the determination of the chip timing
(e.g. clock frequency at SCL). For setup purposes the
IBN bias current is measured using a 10 kΩ resistor by
pin VDDS connected to pin NB. The setpoint is 200 µA
which is equivalent to a voltage drop of 2 V.
Note: The measurement delivers a false reading
when outputs are tristate (due to a configuration error
after cycling power, for instance).
is not relevant to calibration). To avoid confusion a clear
change of state (from low to high) must be generated
with the help of an external pull-up resistor at pin ERR.
Example: VTs(T₁) is ca. 650 mV, measured from VDDS
versus PA, with T₁ = 25 °C;
The necessary reference voltage VTth(T₁) is then cal-
culated. The required warning temperature T₂, temper-
ature coefficients TCs and TCth (see Electrical Char-
acteristics, Section E) and measurement value VTs(T₁)
are entered into this calculation:
CFGIBN
Code k
0x0
0x1
0x2
0x3
0x4
0x5
0x6
0x7
Addr 0x01, bit 7:4
IBN
∼
31
39−k
79 %
81 %
84 %
86 %
88 %
91 %
94 %
97 %
Code k
0x8
0x9
0xA
0xB
0xC
0xD
0xE
0xF
IBN
∼
31
39−k
100 %
103 %
107 %
111 %
115 %
119 %
124 %
129 %
VTth(T₁)
=
VTs(T₁) + TCs · (T₂ − T₁)
1 + TCth · (T₂ − T₁)
Example: For T₂ = T₁ + 100 K VTth(T₁) must be pro-
grammed to 443 mV.
Reference voltage VTth(T₁) is provided for a high
impedance measurement (10 MΩ) at output pin NA
(measurement versus VDDS) and must be set by pro-
gramming CFGTA(3:0) to the calculated value.
Table 11: Calibration of Bias Current
Temperature Sensor
The temperature monitoring is calibrated in operating
mode Calibration 3.
To set the required warning temperature T₂ the tempera-
ture sensor voltage VTs at which the warning message
is generated is first determined. To this end a volt-
age ramp from VDDS towards GNDS is applied to pin
PA until pin ERR displays the warning message. The
following settings are required here: EMASKA = 0x20,
EMTD = 0x00 and EPH = 0x00.
The signal at ERR first switches from tristate to low (on
reaching the warning threshold VTs) and then from low
to tristate (on overshooting the internal hysteresis which
Example: Altering VTth(T₁) from 310 mV (measured
with CFGTA(3:0)= 0x0) to 443 mV is equivalent to
143 %, the closest value for CFGTA is 0x9;
CFGTA
Code k
0x0
0x1
0x2
0x3
0x4
0x5
0x6
0x7
Notes
Addr 0x01, bit 3:0
VTth
∼
65+3k
65
100 %
Code k
0x8
VTth
∼
65+3k
65
140 %
105 %
0x9
145 %
110 %
0xA
150 %
115 %
0xB
155 %
120 %
0xC
160 %
125 %
0xD
165 %
130 %
0xE
170 %
135 %
0xF
175 %
With CFGTA = 0xF Toff is 80 °C typ.,
with CFGTA = 0x0 Toff is 155 °C typ.
Table 12: Calibration of Temperature Monitoring