SM9403BM Datasheet, PDF (17/18 Pages) Nippon Precision Circuits Inc – DVDRAM Servo-amplifier LSI

SM9403BM
Track Count Pulse Generator (TSUB → TRP, TROFF)
This stage filters the tracking error signal through a
6th-order Butterworth low-pass filter which effec-
tively filters off header signal leakage effects. An off-
set voltage is added and the signal passes through a
comparator with hysteresis to generate a track count
pulse signal output on TRP. Simultaneously, the win-
dow comparator corresponding to the tracking error
signal is output as the off-track signal on TROFF
(LOW for off-track).
The offset voltage, hysteresis level and window
width are controlled by serial interface bits.
Table 16. TRP comparator hysteresis
HS3
HS2
HS1
Hysteresis (mV)¹
LOW
LOW
LOW
±100
LOW
LOW
HIGH
±200
LOW
HIGH
LOW
±300
LOW
HIGH
HIGH
±400
HIGH
LOW
LOW
±500
HIGH
LOW
HIGH
≥ 500
Table 15. Offset voltage setting
HIGH
HIGH
LOW
≥ 500
OF3
OF2
OF1
Offset voltage (mV)¹
LOW
LOW
LOW
0
HIGH
HIGH
1. Default is ±100 mV
HIGH
≥ 500
LOW
LOW
HIGH
−2 0 0
Table 17. TROFF comparator window
LOW
HIGH
LOW
−4 0 0
LOW
HIGH
HIGH
−6 0 0
HIGH
LOW
LOW
+800
HIGH
LOW
HIGH
+600
HIGH
HIGH
LOW
+400
HIGH
HIGH
HIGH
+200
1. Default is 0 mV
WD2
LOW
LOW
HIGH
HIGH
1. Default is ±125 mV
WD1
LOW
HIGH
LOW
HIGH
Comparator
window (mV)¹
±125
±250
±375
±475
Sleep Mode
The SM9403BM features 3 sleep modes which can
be used when the device is not operating to signifi-
cantly reduce current consumption. The sleep modes
are controlled by serial interface bits.
Table 18. Sleep mode settings
SL2
SL1
Mode description¹
LOW
LOW
Sleep mode OFF (normal operation)
LOW
HIGH DPD in sleep condition
HIGH
LOW
All except reference voltage supply in
sleep condition
HIGH
HIGH All blocks in sleep condition
1. Default is OFF (SL2 = SL1 = LOW)
Preset Function
When power is applied or in sleep modes 2 and 3, all
serial interface flags are reset to their default values
with the exception of the sleep mode flags SL2 and
SL1 (see the section “Serial Interface”). However,
when writing data to SL2 and SL1 to cancel sleep
mode, other flags in the same data word have prece-
dence when writing to the port.
NIPPON PRECISION CIRCUITS—17