DS1830AS datasheet(2/7 Pages) DALLAS

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D1830/A

2 of 7

OPERATION — POWER MONITOR

The DS1830 provides the functions of detecting out-of-tolerance conditions on a power supply and

warning a processor based system of impending power failure. When VCC is detected as out-of-tolerance

all reset outputs will be forced active. When VCC returns to a valid state, RST1 will remain active for

period of time based on the condition of the TD input. Reset outputs RST2 and RST3 follow RST1 , each

one at the proper delays for the condition of the TD input. All resets will remain in the inactive state

(high) until the next VCC out-of-tolerance condition or pushbutton reset. On power-up all resets are kept

active for an appropriate period determined by the status of the TD input after the power supply inputs

have reached the selected tolerance. This allows the power supply and system power to stabilize before

the reset sequences are released.

BLOCK DIAGRAM Figure 1

OPERATION — TOLERANCE SELECT

The DS1830/A provides a TOL input for individual customization of the DS1830x to specific application

requirements (see Table 1). For the tolerance selection, see Table 1 below. The TOL input is only

sampled while VCC is below the lowest potential trip value and can not be changed after the VCC voltage

exceeds the lowest potential trip value.

TOL — TOLERANCE SELECT Table 1

TOL

5V (DS1830)

3.3V (DS1830A)

VCC

GND

10%

OPEN

(N.C.)

15%

20%

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