TC35680FSG datasheet(64/91 Pages) TOSHIBA

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TC35680FSG-002/TC35681FSG-002

2019-04-04

Adjustment of Oscillation Frequency of Sleep Clock

The adjustment of the oscillation frequency is done by the modification of the capacitance of the variable capacitor. It is done by the

setting of the 5-bit FREQTUNE_OSC32K field in the PMU_OSC32K_TRIMIN register. When a value between 0x00 and 0x1F (2’s

complement) is set, the capacitance of the variable capacitors on the input and output pins changes with a step of about 0.5 pF. Then,

the value 0x0F gives the minimum frequency and 0x10, the maximum frequency.

The value in the FREQTUNE_OSC32K field is 0x00 just after the reset is deasserted or while the cold boot is done. It is set to 0x18

after the oscillation becomes stable. Then the value can be modified by a software procedure.

The oscillation of the sleep clock stops at the transition to the Deep Sleep mode.

Table 4-16 Oscillation condition of Sleep clock and FREQTUNE_OSC32K field value

Connection of Crystal Resonator

Figure 4-21 Connection of Crystal resonator

Use of External Crystal Oscillator

An external clock should be supplied to the SLPXOIN pin after the clock source is assigned to “Direct Input mode” by the command

or the API in Table 4-15. The voltage range of the supplied clock is 0 to VDDIO (V).

A clock should not be supplied to the SLPXOIN pin before “Input from external” is set. The SLPXOOUT pin should be open or be

connected to GND.

In order to supply the clock, the output of the external crystal oscillator should be controlled by the general-purpose output function

of GPIO after the clock change procedure is done.

The external crystal oscillator can be used in Sleep mode and Backup mode. It cannot be used in Deep Sleep mode.

Oscillation condition

Value in FREQTUNE_OSC32K field

J Just after hardware reset is deasserted or wake-up from the Deep

Sleep mode.

0x00 (the initial value at start-up)

0x18 (the initial value after the

oscillation becomes stable)

Input signal

Oscillation control

Trimming control

Input select

SLPXOIN

SLPXOOUT

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