IC-MQF_15 Datasheet, PDF (17/38 Pages) IC-Haus GmbH – Sin/Cos INTERPOLATION IC WITH RS422 DRIVER

iC-MQF PROGRAMMABLE 12-BIT ^preliminary
Sin/Cos INTERPOLATION IC WITH RS422 DRIVER
BIAS CURRENT SOURCE AND TEMPERATURE SENSOR CALIBRATION
Rev C1, Page 17/38
Bias Current
The calibration of the bias current source in operation
mode Calibration 1 (see Table 13) is prerequisite for ad-
herence to the given electrical characteristics and also
instrumental in the determination of the chip timing (e.g.
clock frequency at SCL). The IBN bias current is mea-
sured by connecting pin VDDS and pin NB with a 10 kΩ
resistor. The setpoint is 200 µA which is equivalent to a
voltage drop of 2 V.
Notice: The measurement delivers a false reading
when outputs are tristate (due to a configuration error
after cycling power, for instance).
CFGIBN
Code k
0x0
0x1
0x2
0x3
0x4
0x5
0x6
0x7
Adr 0x00, bit 3:0
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 %
Table 11: Bias Current
Temperature Sensor
The temperature monitoring is calibrated in operating
mode Calibration 3.
The voltage VTs, at which the warning message is gen-
erated, is determined first. A voltage ramp from VDDS
towards GNDS is applied to pin PA until pin ERR dis-
plays the warning message. The following settings
are required for this measurement: EMASKA = 0x20,
EMTD = 0x00 and EPH = 0x00.
The signal at pin ERR switches from tristate to low
(on reaching the warning threshold VTs) and then from
low to tristate (on overshooting the threshold of the
overtemperature self protection which is not relevant to
calibration). To avoid confusion a clear change of state
(from low to high) should 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:
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 against VDDS) and must be set to the
calculated value by programming CFGTA(3:0).
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
0x10-0x1F
Notes
Adr 0x01, bit 4:0
VTth
∼
65+3k
65
100 %
Code k
0x8
VTth
∼
65+3k
65
137 %
105 %
0x9
142 %
109 %
0xA
146 %
114 %
0xB
151 %
118 %
0xC
155 %
123 %
0xD
160 %
128 %
0xE
165 %
132 %
0xF
169 %
reserved
With CFGTA = 0xF Toff is 80 °C typ.,
with CFGTA = 0x0 Toff is 155 °C typ.
Table 12: Temperature Monitoring