ISL12020 datasheet(9/25 Pages) INTERSIL

Teilenummer	ISL12020

Bauteilbeschribung	Low Power RTC with VDD Battery Backed SRAM and Embedded Temp Compensation 짹5ppm with Auto Day Light Saving

Download	25 Pages

Scroll/Zoom	100%

Hersteller	INTERSIL [Intersil Corporation]

Direct Link	http://www.intersil.com/cda/home

Logo

9 / 25 page

9

FN6450.0

March 29, 2007

Battery Level Monitor

The ISL12020 have a built in warning feature once the Back

Up battery level drops first to 85% and then to 75% of the

battery’s nominal VBAT level. When the battery voltage

drops to between 85% and 75%, the LBAT85 bit is set in the

status register. When the level drops below 75%, both

LBAT85 and LBAT75 bits are set in the status register.

There is a Battery Timestamp Function available. Once the

VDD is low enough to enable switchover to the battery, the

RTC time/date are written into the TSVTB register. This

information can be read from the TSVTB registers to

discover the point in time of the VDD powerdown. If there are

multiple powerdown cycles before reading these registers,

the first values stored in these registers will be retained.

These registers will hold the original powerdown value until

they are cleared by writing “00h” to each register.

Low Power Mode

The normal power switching of the ISL12020 is designed to

switch into battery backup mode only if the VDD power is

lost. This will ensure that the device can accept a wide range

of backup voltages from many types of sources while reliably

switching into backup mode. Another mode (called Low

Power Mode) is available to allow direct switching from VDD

to VBAT without requiring VDD to drop below VTRIP. Since

the additional monitoring of VDD vs VTRIP is no longer

needed, that circuitry is shut down and less power is used

while operating from VDD. Power savings are typically

600nA at VDD = 5V. Low Power Mode is activated via the

BSW bit in the control and status registers.

Low Power Mode is useful in systems where VDD is normally

higher than VBAT at all times. The device will switch from

VDD to VBAT when VDD drops below VBAT, with about 50mV

of hysteresis to prevent any switchback of VDD after

switchover. In a system with VDD = 5V and backup lithium

battery of VBAT = 3V, Low Power Mode can be used.

However, it is not recommended to use Low Power Mode in

a system with VDD = 3.3V ±10%, VBAT ≥ 3.0V, and when

there is a finite I-R voltage drop in the VDD line.

Real Time Clock Operation

The Real Time Clock (RTC) uses an external 32.768kHz

quartz crystal to maintain an accurate internal representation

of second, minute, hour, day of week, date, month, and year.

The RTC also has leap-year correction. The clock also

corrects for months having fewer than 31 days and has a bit

that controls 24 hour or AM/PM format. When the ISL12020

powers up after the loss of both VDD and VBAT, the clock will

not begin incrementing until at least one byte is written to the

clock register.

Single Event and Interrupt

The alarm mode is enabled via the MSB bit. Choosing single

event or interrupt alarm mode is selected via the IM bit. Note

that when the frequency output function is enabled, the

alarm function is disabled.

The standard alarm allows for alarms of time, date, day of

the week, month, and year. When a time alarm occurs in

single event mode, an IRQ pin will be pulled low and the

alarm status bit (ALM) will be set to “1”.

The pulsed interrupt mode allows for repetitive or recurring

alarm functionality. Hence, once the alarm is set, the device

will continue to alarm for each occurring match of the alarm

and present time. Thus, it will alarm as often as every minute

(if only the nth second is set) or as infrequently as once a

year (if at least the nth month is set). During pulsed interrupt

mode, the IRQ pin will be pulled low for 250ms and the alarm

status bit (ALM) will be set to “1”.

The ALM bit can be reset by the user or cleared

automatically using the auto reset mode (see ARST bit). The

alarm function can be enabled/disabled during battery

backup mode using the FOBATB bit. For more information

on the alarm, please see “ALARM Registers (10h to 15h)” on

page 17.

Frequency Output Mode

The ISL12020 has the option to provide a clock output signal

using the IRQ/FOUT open drain output pin. The frequency

output mode is set by using the FO bits to select 15 possible

output frequency values from 1/32Hz to 32kHz. The

frequency output can be enabled/disabled during battery

backup mode using the FOBATB bit.

General Purpose User SRAM

The ISL12020 provides 128 bytes of user SRAM. The SRAM

will continue to operate in battery backup mode. However, it

should be noted that the I2C bus is disabled in battery

backup mode.

I2C Serial Interface

The ISL12020 has an I2C serial bus interface that provides

access to the control and status registers and the user

SRAM. The I2C serial interface is compatible with other

industry I2C serial bus protocols using a bi-directional data

signal (SDA) and a clock signal (SCL).

Oscillator Compensation

The ISL12020 provides both initial timing correction and

temperature correction due to variation of the crystal

oscillator. Analog and Digital trimming control is provided for

initial adjustment, and a temperature compensation function

is provided to automatically correct for temperature drift of

the crystal. Initial values for the temperature coefficient

(ALPHA) and crystal capacitance (BETA) are required for

best accuracy. The function can be enabled/disabled at any

time and can be used in battery mode as well.

ISL12020

Ähnliche Beschreibung - ISL12020

Hersteller	Teilenummer	Datenblatt	Bauteilbeschribung
Renesas Technology Corp	ISL12023	1Mb / 29P	Low Power RTC with Battery-Backed SRAM and Embedded Temp Compensation 짹5ppm with Auto Daylight Saving
Intersil Corporation	ISL12023	389Kb / 28P	Low Power RTC with Battery-Backed SRAM and Embedded Temp Compensation 짹5ppm with Auto Daylight Saving
Renesas Technology Corp	ISL12022	1Mb / 29P	Low Power RTC with Battery-Backed SRAM and Embedded Temp Compensation 짹5ppm with Auto Daylight Saving
Intersil Corporation	ISL12022MIBZ-T7A	900Kb / 31P	Low Power RTC with Battery Backed SRAM, Integrated 짹5ppm Temperature Compensation and Auto Daylight Saving
Intersil Corporation	ISL12020M	476Kb / 32P	Low Power RTC with Battery Backed SRAM, Integrated 짹5ppm Temperature Compensation and Auto Daylight Saving
Renesas Technology Corp	ISL12022MA	1Mb / 31P	Low Power RTC with Battery Backed SRAM, Integrated 짹5ppm Temperature Compensation and Auto Daylight Saving
	ISL12022MR5421	1Mb / 31P	Low Power RTC with Battery Backed SRAM, Integrated 짹5ppm Temperature Compensation and Auto Daylight Saving
	ISL12020M	1Mb / 34P	Low Power RTC with Battery Backed SRAM, Integrated 짹5ppm Temperature Compensation and Auto Daylight Saving
Intersil Corporation	ISL12022M	620Kb / 31P	Low Power RTC with Battery Backed SRAM,Integrated 짹5ppm Temperature Compensation and Auto Daylight Saving
Intersil Corporation	ISL12022MA	866Kb / 29P	Low Power RTC with Battery Backed SRAM, Integrated 짹5ppm Temperature Compensation and Auto Daylight Saving

More results

ISL12020 Datenblatt(PDF) 9 Page - Intersil Corporation

ISL12020 Datenblatt(HTML) 9 Page - Intersil Corporation

Ähnliche Teilenummer - ISL12020

Ähnliche Beschreibung - ISL12020

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

Datenblatt Download

Link URL