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PDF DS1689 Data sheet ( Hoja de datos )
| Número de pieza | DS1689 | |
| Descripción | (DS1689 / DS1693) 3-Volt/5-Volt Serialized Real-Time Clock | |
| Fabricantes | Dallas Semiconductor | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de DS1689 (archivo pdf) en la parte inferior de esta página. Total 32 Páginas | ||
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www.maxim-ic.com
DS1689/DS1693
3-Volt/5-Volt Serialized Real-Time Clock
with NV RAM Control
FEATURES
Incorporates industry standard DS1287 PC clock
plus enhanced features:
§ +3- or +5V operation
§ 64-bit silicon serial number
§ 64-bit customer specific ROM or additional
serial number available
§ Power control circuitry supports system
power-on from date/time alarm or key closure
§ Automatic battery backup and write
protection to external SRAM
§ Crystal select bit allows RTC to operate with
6 pF or 12.5 pF crystal
§ 114 bytes user NV RAM
§ Auxiliary battery input
§ RAM clear input
§ Century register
§ 32 kHz output for power management
§ 32-bit VCC powered elapsed time counter
§ 32-bit VBAT powered elapsed time counter
§ 16-bit power cycle counter
§ Compatible with existing BIOS for original
DS1287 functions
§ Available as IC (DS1689) or standalone
module with embedded battery and crystal
(DS1693)
§ IC is available in industrial temperature
version
§ Timekeeping algorithm includes leap year
compensation valid up to 2100
ORDERING INFORMATION
PART #
DS1689S
DS1689SN
DS1693
DESCRIPTION
RTC IC, 28-pin SOIC
RTC IC, 28-pin SOIC IND
RTC Module; 28-pin DIP
PIN ASSIGNMENT
VBAUX
NC
NC
RCLR
AD0
AD1
AD2
AD3
AD4
AD5
AD6
AD7
PWR
GND
1
2
3
4
5
6
7
8
9
10
11
12
13
14
28 CEI
27 CEO
26 VCCI
25 VCCO
24 SQW
23 NC
22 IRQ
21 PSEL
20 RD
19 NC
18 WR
17 ALE
16 CS
15 KS
VBAUX
X1
X2
RCLR
AD0
AD1
AD2
AD3
AD4
AD5
AD6
AD7
PWR
GND
1
2
3
4
5
6
7
8
9
10
11
12
13
14
28 CEI
27 CEO
26
25
VCCI
VCCO
24 SQW
23 VBAT
22 IRQ
21 PSEL
20 RD
19 GND
18 WR
17 ALE
16 CS
15 KS
DS1693 28-Pin Encapsulated Package DS1689S 28-Pin SOIC
(740-mil)
(330-mil)
PIN DESCRIPTION
X1 - Crystal Input
X2 - Crystal Output
RCLR
- RAM Clear Input
AD0-AD7 - Mux’ed Address/Data Bus
PWR - Power-on Interrupt Output
(Open drain)
KS - Kickstart Input
CS - RTC Chip Select Input
ALE - RTC Address Strobe
WR - RTC Write Data Strobe
RD
VCCO
IRQ
SQW
VCCI
GND
VBAT
VBAUX
PSEL
- RTC Read Data Strobe
- RAM Power Supply Output
- Interrupt Request Output
(Open drain)
- Square Wave Output
- +3- or +5V Main Supply
- Ground
- Battery + Supply
- Auxiliary Battery Supply
- +3- or +5V Power Select
CEI - RAM Chip Enable In
CEO - RAM Chip Enable Out
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DS1689/DS1693
KS (Kickstart Input; active low) - When VCC is removed from the DS1689/DS1693, the system can be
powered on in response to an active low transition on the KS pin, as might be generated from a key
closure. VBAUX must be present and Auxiliary Battery Enable bit (ABE) must be set to 1 if the kickstart
function is used, and the KS pin must be pulled up to the VBAUX supply. While VCC is applied, the KS pin
can be used as an interrupt input.
RCLR (RAM Clear Input; active low) - If enabled by software, taking RCLR low will result in the
clearing of the 114 bytes of user RAM. When enabled, RCLR can be activated whether or not VCC is
present.
VBAUX - Auxiliary battery input required for kickstart and wake-up features. This input also supports
clock/calendar and External NVRAM if VBAT is at lower voltage or is not present. A standard +3-volt
lithium cell or other energy source can be used. Battery voltage must be held between +2.5 and +3.7 volts
for proper operation. If VBAUX is not going to be used it should be grounded and auxiliary battery enable
bit bank 1, register 4BH, should=0.
DS1689 ONLY
X1, X2 - Connections for a standard 32.768 kHz quartz crystal. For greatest accuracy, the DS1689 must
be used with a crystal that has a specified load capacitance of either 6 pF or 12.5 pF. The Crystal Select
(CS) bit in Extended Control Register 4B is used to select operation with a 6 pF or 12.5 pF crystal. The
crystal is attached directly to the X1 and X2 pins. There is no need for external capacitors or resistors.
Note: X1 and X2 are very high impedance nodes. It is recommended that they and the crystal by guard-
ringed with ground and that high frequency signals be kept away from the crystal area.
For more information on crystal selection and crystal layout considerations, please consult Application
Note 58, “Crystal Considerations with Dallas Real Time Clocks.” The DS1689 can also be driven by an
external 32.768 kHz oscillator. In this configuration, the X1 pin is connected to the external oscillator
signal and the X2 pin is floated.
VBAT - Battery input for any standard 3-Volt lithium cell or other energy source. Battery voltage must be
held between 2.5 and 3.7 volts for proper operation.
POWER-DOWN/POWER-UP CONSIDERATIONS
The real-time clock function will continue to operate and all of the RAM, time, calendar, and alarm
memory locations remain nonvolatile regardless of the level of the VCCI input. When VCCI is applied to
the DS1689/DS1693 and reaches a level of greater than VPF (power fail trip point), the device becomes
accessible after tREC, provided that the oscillator is running and the oscillator countdown chain is not in
reset (see Register A). This time period allows the system to stabilize after power is applied.
When PSEL is floating or logic 0, the DS1689 is in autosense mode and 3-volt or 5-volt operation is
determined based on the voltage on VCCI. Selection of 5-volt operation is automatically invoked when
VCCI rises above 4.5 volts for a minimum of tREC. However, 3-volt operation is automatically selected if
VCCI does not rise above the level of 4.25 volts. Selection of the power supply input levels requires
150 ms of input stability before operation can commence.
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PERIODIC INTERRUPT RATE AND
SQUARE WAVE OUTPUT FREQUENCY Table 2
EXT. REG. B SELECT BITS REGISTER A
E32K
RS3 RS2 RS1 RS0
tPI PERIODIC
INTERRUPT RATE
0 0 0 0 0 None
0 0 0 0 1 3.90625 ms
0 0 0 1 0 7.8125 ms
0 0 0 1 1 122.070 ms
0 0 1 0 0 244.141 ms
0 0 1 0 1 488.281 ms
0 0 1 1 0 976.5625 ms
0 0 1 1 1 1.953125 ms
0 1 0 0 0 3.90625 ms
0 1 0 0 1 7.8125 ms
0 1 0 1 0 15.625 ms
0 1 0 1 1 31.25 ms
0 1 1 0 0 62.5 ms
0 1 1 0 1 125 ms
0 1 1 1 0 250 ms
0 1 1 1 1 500 ms
1 X X X X*
*RS3-RS0 determine periodic interrupt rates as listed for E32K=0.
DS1689/DS1693
SQW OUTPUT
FREQUENCY
None
256 Hz
128 Hz
8.192 kHz
4.096 kHz
2.048 kHz
1.024 kHz
512 Hz
256 Hz
128 Hz
64 Hz
32 Hz
16 Hz
8 Hz
4 Hz
2 Hz
32.768 kHz
The third method uses a periodic interrupt to determine if an update cycle is in progress. The UIP bit in
Register A is set high between the setting of the PF bit in Register C (see Figure 3). Periodic interrupts
that occur at a rate of greater than tBUC allow valid time and date information to be reached at each
occurrence of the periodic interrupt. The reads should be complete within (tPI / 2+tBUC) to ensure that data
is not read during the update cycle.
UPDATE-ENDED AND PERIODIC INTERRUPT RELATIONSHIP Figure 3
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11 Page | ||
| Páginas | Total 32 Páginas | |
| PDF Descargar | [ Datasheet DS1689.PDF ] | |
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