IC-MQF_15 Datasheet, PDF (29/38 Pages) IC-Haus GmbH – Sin/Cos INTERPOLATION IC WITH RS422 DRIVER

iC-MQF PROGRAMMABLE 12-BIT ^preliminary
Sin/Cos INTERPOLATION IC WITH RS422 DRIVER
Rev C1, Page 29/38
Output Driver Configuration
The output drivers can be used as push-pull, lowside or
highside drivers; the mode of operation is determined
by TRIHL(1:0).
The slew rate can be set using SSR to suit the length
of the cable. Lower slew rates are used to avoid steep
edges when transmitting via short wires, but can re-
sult in a limiting of the maximum permissible output
frequency. (For example, this frequency is 300 kHz at a
slew rate of 300 ns if the RS422 specification is to be
adhered to. (the tolerances in Electrical Characteristics,
numbers 506/507, must be observed)).
The short-circuit current can be set by SIK and can
be minimized when connecting to on board logic or to
an external 24 V line driver. If the outputs are used as
RS422-compatible 5 V drivers, it is recommended that
SIK = 11 to keep the power dissipation of iC-MQF low.
TRIHL
Code
00
01
10
11
Addr 0x22, bit 1:0
Function
Push-pull operation
Highside driver mode (P channel open drain)
Lowside driver mode (N channel open drain)
Not permitted
Table 44: Output Drive Mode
SSR
Code
00
01
10
11
Note
Addr 0x22, bit 3:2
Function
Nominal value 12 ns
Nominal value 25 ns
Nominal value 80 ns
Nominal value 220 ns
See Elec. Char. 505/ 506
CFGOSZ
Code k
0x0
0x1
0x2
0x3
Addr 0x25, bit 2:0
140 %
130 %
120 %
110 %
Code k
0x4
0x5
0x6
0x7
105 %
100 %
92 %
n/a
Table 47: Calibration of MTD Oscillator
The calibration must be executed in Mode 191/193 with
register MTD(3:0) = 0x0F. Apply a sine signal at the in-
puts X3 to X6 and observe the length of the low pulses
at pin PB. The setting of CFGOSZ is correct if the ob-
served tclk()lo is close to the nominal value of Elec.
Char. no. 511.
MTD
Code
0x0
0x1
0x2
0x3
0x4
0x5
0x6
0x7
0x8
0x9
0xA
0xB
0xC
0xD
0xE
0xF
Note
Addr 0x1F, bit 7:4
Mode ABZ: t_MTD
not available
Mode 191/193: tclk()lo
not available
50 ns
not available
75 ns
not available
100 ns
50 ns
125 ns
62.5 ns
150 ns
75 ns
175 ns
87.5 ns
200 ns
100 ns
300 ns
150 ns
400 ns
200 ns
600 ns
300 ns
800 ns
400 ns
1.0 µs
500 ns
1.2 µs
600 ns
1.4 µs
700 ns
1.6 µs
800 ns
All timing specifications are nominal values, see
Elec. Char. 514 for tolerances.
Table 48: Minimum Transition Distance
SIK
Code
00
01
10
11
Note
Table 45: Output Slew Rate
Addr 0x22, bit 5:4
Function
typ. 2 mA, linking logic or driver ICs
typ. 8 mA
typ. 40 mA
typ. 100 mA, recommended for RS422
See Elec. Char. 503/ 504
If CFGOSZ(2:0) is set correctly, the minimum transi-
tion distance of the output signals can be preset by
MTD(3:0). This setting limits the maximum possible out-
put frequency to ensure a safe transmission to counters,
which permit only a low input frequency and thus can-
not debounce spikes. The configuration of the RS422
output drivers (with regard to the driver current and slew
rate) and the cable length must be taken into account
when choosing the minimum edge distance.
Table 46: Output Short-Circuit Current
Signal Filter
Minimum Transition Distance
ENF
Register CFGOSZ(2:0) calibrates the timing of t_MTD, the ^Code
minimum transition distance in Mode ABZ, and tclk()lo, 0
the low pulse duration of the clock signals in Mode 1
191/193 (see Elec.Char., no. 511 and no. 514).
Addr 0x03, bit 7
Function
Disabled
Noise limiting signal filter enabled (default)
Table 49: Noise Filter