MSM6575 Ver la hoja de datos (PDF) - Oki Electric Industry

Número de pieza

componentes Descripción

Fabricante

MSM6575

Operatable at 0.9 V and Built-in Buzzer Circuit 4-Bit Microcontroller

Oki Electric Industry 

¡ Semiconductor

MSM6545/6575/6545L/6575L

NOTES ON USE

Power Supply for 0.9 V Microcontroller Series (Backup Flag and Constant-Voltage Circuit)

The 0.9 V devices have a built-in constant-voltage circuit. The output of this constant-voltage

circuit powers the microcontroller's internal logic circuits. Setting a backup flag (BUF) allows

the input of the constant voltage circuit to be switched to either the battery or the output

generated in the voltage converter, based on the battery voltage. A battery voltage of 1.5 V or

3.0 V can be selected.

VDD

(0 V)

VSS1

(–1.5 V)

VSS2

(–3.0 V)

VSS3*

(–4.5 V)

Voltage converter

Backup flag

(BUF)

Internal logic XT

XTB

Constant voltage circuit

VR

XTAL

VEE

(About–1.3 V)

LCD driver* * The VSS3 pin is provided for the devices that contain an

LCD driver.

The output (VEE) of the constant-voltage circuit is set at approximately –1.3 V. This allows the

current consumed by the internal logic to be limited, irrespective of the battery voltage.

However, if the input of the constant voltage circuit is below this set value (approximately –

1.3V), the output (VEE) is equal to the input. The 0.9 V microcontroller can be operated even if

the internal voltage (output from the constant voltage circuit) falls to 0.9 V. Setting the backup

flag allows a larger operating voltage margin despite changes in internal voltage due to noise.

For example, for the 1.5 V specification, setting the backup flag at "0" supplies twice the battery

voltage to the constant voltage circuit. Thus, even if the battery voltage falls to 0.9 V, the output

voltage (VEE) is maintained at –1.3 V, providing a larger margin of operating voltage of the

internal logic circuits, because 1.8 V is applied to the input of the constant-voltage circuit.

Figures 1 to 4 show the internal status depending on the backup flag settings for the battery, as

well as status features.

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