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參數(shù)資料
| 型號： | DS3234S |
| 廠商： | Maxim Integrated Products, Inc. |
| 英文描述： | Extremely Accurate SPI Bus RTC with Integrated Crystal and SRAM |
| 中文描述： | 非常精確的時鐘SPI總線集成晶體和SRAM |
| 文件頁數(shù)： | 10/20頁 |
| 文件大?。?/td> | 328K |
| 代理商： | DS3234S |
D
Extremely Accurate SPI Bus RTC with
Integrated Crystal and SRAM
10
____________________________________________________________________
two programmable time-of-day alarms and a program-
mable square-wave output. The
INT
/SQW provides either
an interrupt signal due to alarm conditions or a square-
wave output. The clock/calendar provides seconds, min-
utes, hours, day, date, month, and year information. The
date at the end of the month is automatically adjusted for
months with fewer than 31 days, including corrections for
leap year. The clock operates in either the 24-hour or 12-
hour format with
AM
/PM indicator. Access to the internal
registers is possible through an SPI bus interface.
A temperature-compensated voltage reference and
comparator circuit monitors the level of V
CC
to detect
power failures and to automatically switch to the backup
supply when necessary. When operating from the back-
up supply, access is inhibited to minimize supply cur-
rent. Oscillator, time and date, and TCXO operations can
continue while the backup supply powers the device.
The
RST
pin provides an external pushbutton function
and acts as an indicator of a power-fail event.
Operation
The block diagram shows the main elements of the
DS3234. The eight blocks can be grouped into four
functional groups: TCXO, power control, pushbutton
function, and RTC. Their operations are described sep-
arately in the following sections.
32kHz TCXO
The temperature sensor, oscillator, and control logic form
the TCXO. The controller reads the output of the on-chip
temperature sensor and uses a lookup table to determine
the capacitance required, adds the aging correction in
the AGE register, and then sets the capacitance selection
registers. New values, including changes to the AGE reg-
ister, are loaded only when a change in the temperature
value occurs. The temperature is read on initial applica-
tion of V
CC
and once every 64 seconds (default, see the
description for CRATE1 and CRATE0 in the
Control/Status
Register
section) afterwards.
Power Control
The power control function is provided by a tempera-
ture-compensated voltage reference and a comparator
circuit that monitors the V
CC
level. The device is fully
accessible and data can be written and read when V
CC
is greater than V
PF
. However, when V
CC
falls below
both V
PF
and V
BAT
, the internal clock registers are
blocked from any access. If V
PF
is less than V
BAT
, the
device power is switched from V
CC
to V
BAT
when V
CC
drops below V
PF
. If V
PF
is greater than V
BAT
, the
device power is switched from V
CC
to V
BAT
when V
CC
drops below V
BAT
. After V
CC
returns above both V
PF
and V
BAT
, read and write access is allowed after
RST
goes high (Table 1).
To preserve the battery, the first time V
BAT
is applied to
the device, the oscillator does not start up until V
CC
crosses V
PF
. After the first time V
CC
is ramped up, the
oscillator starts up and the V
BAT
source powers the
oscillator during power-down and keeps the oscillator
running. When the DS3234 switches to V
BAT
, the oscil-
lator may be disabled by setting the
EOSC
bit.
Pushbutton Reset Function
The DS3234 provides for a pushbutton switch to be con-
nected to the
RST
output pin. When the DS3234 is not in
a reset cycle, it continuously monitors the
RST
signal for a
low going edge. If an edge transition is detected, the
DS3234 debounces the switch by pulling the
RST
low.
After the internal timer has expired (PB
DB
), the DS3234
continues to monitor the
RST
line. If the line is still low, the
DS3234 continuously monitors the line looking for a rising
edge. Upon detecting release, the DS3234 forces the
RST
pin low and holds it low for t
RST
.
The same pin,
RST
, is used to indicate a power-fail con-
dition. When V
CC
is lower than V
PF
, an internal power-fail
signal is generated, which forces the
RST
pin low. When
V
CC
returns to a level above V
PF
, the
RST
pin is held low
for t
REC
to allow the power supply to stabilize. If the
EOSC
bit is set to logic 1 (to disable the oscillator in bat-
tery-backup mode), the reset signal is kept active for
t
REC
plus the startup time of the oscillator (typ 1 second).
SUPPLY CONDITION
READ/WRITE
ACCESS
No
Yes
Yes
Yes
ACTIVE
SUPPLY
V
BAT
V
CC
V
CC
V
CC
RST
V
CC
< V
PF
, V
CC
< V
BAT
V
CC
< V
PF
, V
CC
> V
BAT
V
CC
> V
PF
, V
CC
< V
BAT
V
CC
> V
PF
, V
CC
> V
BAT
Active
Active
Inactive
Inactive
Table 1. Power Control
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相關(guān)代理商/技術(shù)參數(shù) |
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|---|---|
| DS3234S- | 制造商:MAXIM 制造商全稱:Maxim Integrated Products 功能描述:Extremely Accurate SPI Bus RTC with Integrated Crystal and SRAM |
| DS3234S# | 功能描述:實(shí)時時鐘 Integrated RTC/TCXO/Crystal RoHS:否 制造商:Microchip Technology 功能:Clock, Calendar. Alarm RTC 總線接口:I2C 日期格式:DW:DM:M:Y 時間格式:HH:MM:SS RTC 存儲容量:64 B 電源電壓-最大:5.5 V 電源電壓-最小:1.8 V 最大工作溫度:+ 85 C 最小工作溫度: 安裝風(fēng)格:Through Hole 封裝 / 箱體:PDIP-8 封裝:Tube |
| DS3234S# | 制造商:Maxim Integrated Products 功能描述:RTC TCXO CRYSTAL 3.3V 20SOIC 制造商:Maxim Integrated Products 功能描述:RTC, TCXO, CRYSTAL, 3.3V, 20SOIC 制造商:Maxim Integrated Products 功能描述:RTC, TCXO, CRYSTAL, 3.3V, 20SOIC; Date Format:DD:MM:YYYY; Clock Format:HH:MM:SS; Clock IC Type:RTC; Supply Voltage Min:2V; Supply Voltage Max:5.5V; Digital IC Case Style:SOIC; No. of Pins:20; Interface Type:SPI; Operating Temperature;RoHS Compliant: Yes |
| DS3234S#T&R | 制造商:Maxim Integrated Products 功能描述:REAL TIME CLOCK SERL 256BYTE 20SOIC W - Tape and Reel 制造商:Maxim Integrated Products 功能描述:IC RTC W/TCXO 20-SOIC |
| DS3234S#T&R | 功能描述:實(shí)時時鐘 Integrated RTC/TCXO/Crystal RoHS:否 制造商:Microchip Technology 功能:Clock, Calendar. Alarm RTC 總線接口:I2C 日期格式:DW:DM:M:Y 時間格式:HH:MM:SS RTC 存儲容量:64 B 電源電壓-最大:5.5 V 電源電壓-最小:1.8 V 最大工作溫度:+ 85 C 最小工作溫度: 安裝風(fēng)格:Through Hole 封裝 / 箱體:PDIP-8 封裝:Tube |
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