STM690 datasheet(12/32 Pages) STMICROELECTRONICS

12 / 32 page

STM690/704/795/802/804/805/806

12/32

Using a SuperCap™ as a Backup Power

Source

SuperCaps™ are capacitors with extremely high

capacitance values (e.g., order of 0.47F) for their

size. Figure 15 shows how to use a SuperCap as

a back-up power source. The SuperCap may be

connected through a diode to the VCC supply.

Since VBAT can exceed VCC while VCC is above

the reset threshold, there are no special precau-

tions when using these supervisors with a Super-

Cap.

Figure 15. Using a SuperCap™

Negative-Going VCC Transients

The STM690/704/795/802/804/805/806 Supervi-

sors are relatively immune to negative-going VCC

transients (glitches). Figure 33., page 21 was gen-

erated using a negative pulse applied to VCC,

starting at VRST + 0.3V and ending below the reset

threshold by the magnitude indicated (comparator

overdrive). The graph indicates the maximum

pulse width a negative VCC transient can have

without causing a reset pulse. As the magnitude of

the transient increases (further below the thresh-

old), the maximum allowable pulse width decreas-

es. Any combination of duration and overdrive

which lies under the curve will NOT generate a re-

set signal. Typically, a VCC transient that goes

100mV below the reset threshold and lasts 40µs or

less will not cause a reset pulse. A 0.1µF bypass

capacitor mounted as close as possible to the VCC

pin provides additional transient immunity.

AI08805

STMXXX

VBAT

VCC

VOUT

GND

RST

To external SRAM

To µP

STM690 数据表(PDF) 12 Page - STMicroelectronics

STM690 数据表(HTML) 12 Page - STMicroelectronics

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

数据表下载