STM6779 datasheet(4/25 Pages) STMICROELECTRONICS

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STM6717/6718/6719/6720/6777/6778/6779*/6780*

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SUMMARY DESCRIPTION

The STM6717/18/19/20 and STM6777/78/79/80

Supervisors are a family of low voltage/low supply

current processor (Micro or DSP) Supervisors, de-

signed to monitor two (or three) system power

supply voltages. They are targeted at applications

such as Set-Top Boxes (STBs), portable, battery-

powered systems, networking, and communica-

tion systems.

All device options have a push-button-type manu-

al reset input (MR). The STM6777/78/79/80 also

includes an option which enables the user to delay

the start of the Manual Reset process from 6µs

(MRC pin left open) or more with external capaci-

tor. The delay is implemented by connecting the

appropriately sized capacitor between the MRC

pin and VSS (typical 4s delay with a 3.3µF capaci-

tor, see Table 7., page 19).

Two of the three supplies monitored (VCC1 and

VCC2) have fixed (customer-selectable, factory-

trimmed) thresholds (VRST1 and VRST2). The third

voltage is monitored using an externally adjust-

able RSTIN threshold (0.626V internal reference).

If any of the three monitored voltages drop below

its factory-trimmed or adjustable thresholds, or if

MR is asserted to logic low, a RST is asserted

(driven low). Once asserted, RST is maintained at

Low for a minimum delay period (trec) after ALL

supplies rise above their respective thresholds

and MR returns to High. These devices are guar-

anteed to be in the correct reset output logic state

when VCC1 and/or VCC2 is greater than 0.8V.

These devices are available in a standard 5-pin or

6-pin SOT23 packages (see Table 1., page 1).

Figure 2. Logic Diagram (STM6717/18)

Figure 3. Logic Diagram (STM6719/20)

Figure 4. Logic Diagram (STM6777/78)

Figure 5. Logic Diagram (STM6779/80)

AI10413

VCC1

STM6717

STM6718

VSS

VCC2

RST

AI10414

VCC1

STM6719

STM6720

VSS

VCC2

RST

RSTIN

AI10415

VCC1

STM6777

STM6778

VSS

VCC2

RST

MRC

AI10416

VCC

STM6779

STM6780

VSS

RST

MRC

RSTIN

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