EM6517 datasheet(38/64 Pages) EMMICRO

38 / 64 page

EM6517

03/02 REV. C/448

 2002, EM Microelectronic-Marin SA

www.emmicroelectronic.com

12 Supply Voltage Level Detector

The EM6517 has a built-in Supply Voltage Level Detector (SVLD) circuitry, such that the CPU can compare the

supply voltage against a pre-selected value. During sleep mode this function is inhibited.

The CPU activates the supply voltage level

detector by writing VldStart = 1 in the register

RegVldCntl

. The actual measurement starts on

the next Ck[9] rising edge and lasts during the

Ck[9] high period (2 ms at 32 KHz). The busy

flag VldBusy stays high from VldStart set until

the measurement is finished. The worst case

time until the result is available is 1.5 Ck[9]

prescaler clock periods (32 KHz -> 6 ms). The

detection level must be defined in register

RegVldLevel

before the VldStart bit is set.

During the actual measurement (2 ms) the

device will draw an additional 5 µA of IVDD

current. After the end of the measure the result

is available by inspection of the bit VldResult.

An interrupt IRQVLD is send to indicate the end

of measure. If the result is read 0, then the

power supply voltage was greater than the detection level value. If read 1, the power supply voltage was lower

than the detection level value. During each read while Busy=1 the VldResult is not guaranteed. The interrupt

request can be masked (default) (MaskIRQVLD bit).

12.1 SVLD Register

Table 12.1.1 register RegVldCntl

Bit

Name

Reset

R/W

Description

VLDResult

Vld result flag

VLDStart

Vld start

VLDBusy

Vld busy flag

VLDlevel1

R/W

Vld level selection

VLDlevel0

R/W

Vld level selection

R*; VLDResult is not guaranteed while VLDBusy=1

Table 12.1.2 Voltage level detector value selecting

Level

VldLevel1

VldLevel0

Typical voltage level

Level1

2.2

Level2

2.5

Level3

3.0

Level3

3.0

Figure 28. SVLD Timing Diagram

VBAT =VDD

Compare Level

Ck[9] (256 Hz)

CPU starts

measure

Busy Flag

Measure

Result

Read Result

SVLD > VBAT

SVLD < VBAT

CPU starts

measure

EM6517 Datasheet(PDF) 38 Page - EM Microelectronic - MARIN SA

EM6517 Datasheet(HTML) 38 Page - EM Microelectronic - MARIN SA

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 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64

Datasheet Download

Link URL