SPC21A1 View Datasheet(PDF) - Unspecified

Part Name

Description

Manufacturer

SPC21A1

20KB SOUND CONTROLLER

Unspecified 

SPC21A1

POWER SAVINGS MODE

The SPC21A1 provides a power savings mode (Standby mode) for those applications that require very low

stand-by current. To enter standby mode, the Wake-Up Register should be enabled and then stop the CPU

clock by writing the STOP CLOCK Register. The CPU will then go to the stand-by mode. In such a mode,

RAM and I/Os will remain in their previous states until being awakened. Port IOD7-0 is the only wake-up

source in the SPC21A1. After the SPC21A1 is awakened, the internal CPU will go to the RESET State (Tw

65536 x T1) and then continue processing the program. Wakeup Reset will not affect RAM or I/Os (FIG.1).

Sleep

CPU

CLK

Reset

Wake-up

T1

Tw

FIG. 1

T1 = 1 / ( FCPU ), Tw 65536 x T1

LOW VOLTAGE RESET

The SPC21A1 includes a Low Voltage Reset (LVR) function. Below the minimum power-supply voltage of 2.2V,

the CPU system will become unstable and malfunction. Low Voltage Reset will reset all functions into the initial

operational (stable) state if the VDD power-supply voltage drops below 2.2V (FIG.2).

T1

CPU CLK

VDD

2.2V

T2

RESET

TW

Á T2 2 * T1

(The LVR function is the same as Power ON Reset or External Reset.)

FIG. 2

Sunplus Technology Co., Ltd.

4

Rev.: 1.1 1999.11.19

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