SM9103M datasheet(13/14 Pages) NPC

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SM9103M

NIPPON PRECISION CIRCUITS—13

Offset Correction

The SM9103M has built-in offset correction circuits

for tracking and focus. During offset correction, the

internal the device operates in RAM read mode, and

FSUB and TSUB operate at maximum gain

(+14 dB). The outputs on FSUB, FADD and TSUB

are indeterminate. Also, inputs T1, T2, T3, T4 and

F1, F2 may be ignored. After correction is complete,

the FSUB and TSUB gain settings return to their

default values (0 dB).

Offset correction is performed under the following

conditions:

When power is applied.

When the supply drops below 2.8 ± 0.9 V and then

rises to above 3.8 ± 0.6 V.

When sleep mode operation is cancelled.

When the serial interface bit CS1 is 1. Note that if

SL1 is also 1, then SL1 has priority.

If the voltage falls below 2.8 ± 0.9 V during offset

correction, then correction stops and does not restart

until the supply recovers to above 3.8 ± 0.6 V.

During offset correction, the CALREQ output is held

HIGH. CALREQ goes LOW after correction stops.

The SM9103M also incorporates a temperature

detect function which detects temperature changes of

20 ± 5

°C from the time the initial correction is per-

formed. If a temperature change is detected, CAL-

REQ goes HIGH and the device waits for an offset

correction instruction.

Note that when both WRITE and MODE are HIGH,

offset correction is inactive and the output appears

uncorrected. However, if a correction start condition

occurs when correction is inactive, such as the cor-

rection ﬂag CS1 set to 1, then correction operation is

initiated internally but does not appear at the output

unless correction is activated prior to correction

operation ﬁnishing.

Once correction has been made inactive, the output

remains uncorrected even if correction is subse-

quently reactivated. In this case, the output remains

uncorrected until a valid correction start condition is

detected.

Sleep Mode

The SM9103M features a sleep mode which can be

used when the device is not operating to signiﬁcantly

reduce current consumption. The sleep mode is con-

trolled by serial interface bit SL1.

Preset Function

When power is applied or after offset correction, all

serial interface ﬂags are reset to their default values.

Flags TG3 to TG0 and FG3 to FG0 are also set to

their default values in sleep mode.

Table 4. Offset correction setting

CS1

Offset correction1

1. Default is No correction

No correction

Correction

Table 5. Sleep mode settings

SL1

Sleep mode1

Mode description

LOW

OFF

Normal operation

HIGH

Sleep condition

1. Default is OFF

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