Restrictions on the Voltage Detection Circuit

Oct,2009

This is to inform you of restrictions on the voltage detection circuit in the TLCS-870/C1 Series, TLCS-870/X Series and TLCS-870/C Series of microcontrollers.
If you need any further information, please contact your local Toshiba sales representative.

Restrictions

1. INTVLTD Interrupt Request

When interrupt generation is enabled in the voltage detection circuit, an INTVLTD interrupt request may be generated not only when the supply voltage falls to the detection voltage level, but also when it rises to the detection voltage level.
In ICE mode of the In-Circuit Emulator (TMP89C900), no interrupt request is generated when the supply voltage rises to the detection voltage level. Therefore, with products supporting the In-Circuit Emulator (TMP89C900), the interrupt generation operation may differ between the development tool and the actual product.

2. Releasing STOP Mode by Voltage Detection

The SRSS bit in the voltage detection control register 2 (VDCR2) provided for releasing STOP mode by voltage detection cannot be used because it does not function as expected.

Workarounds

1. INTVLTD Interrupt Request

Do not use the INTVLTD interrupt for voltage detection. The voltage level should be regularly checked using other timing such as the execution cycle of the main program. VDCR1<VDxSF> (x=1, 2) can be used to check the voltage level. However, if the operating voltage is near the detection voltage, the VDCR1<VDxSF> value may become unstable. It is recommended that VDCR1<VDxSF> be tested multiple times to determine the voltage level.

2. Releasing STOP Mode by Voltage Detection

Always set VDCR2<SRSS> to "00". Use the STOP pin to release STOP mode.

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Restrictions

INTVLTD Interrupt Request

When interrupt generation is enabled in the voltage detection circuit, an INTVLTD interrupt request may be generated not only when the supply voltage falls to the detection voltage level, but also when it rises to the detection voltage level.

Workarounds

INTVLTD Interrupt Request

Do not use the INTVLTD interrupt for voltage detection. The voltage level should be regularly checked using other timing such as the execution cycle of the main program. VDCR1<VD1SF> can be used to check the voltage level. However, if the operating voltage is near the detection voltage, the VDCR1<VD1SF> value may become unstable. It is recommended that VDCR1<VD1SF> be tested multiple times to determine the voltage level.

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Important Notices top

Restrictions

INTVLTD Interrupt Request

When interrupt generation is enabled in the voltage detection circuit, an INTVLTD interrupt request may be generated not only when the supply voltage falls to the detection voltage level, but also when it rises to the detection voltage level.

Workarounds

INTVLTD Interrupt Request

Do not use the INTVLTD interrupt for voltage detection. The voltage level should be regularly checked using other timing such as the execution cycle of the main program. VDCR1<VDxSF> (x=1, 2) can be used to check the voltage level. However, if the operating voltage is near the detection voltage, the VDCR1<VDxSF> value may become unstable. It is recommended that VDCR1<VDxSF> be tested multiple times to determine the voltage level.

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