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参数资料
| 型号： | DS1390U-3 |
| 厂商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分类： | XO, clock |
| 英文描述： | Low-Voltage SPI/3-Wire RTCs with Trickle Charger |
| 中文描述： | 1 TIMER(S), REAL TIME CLOCK, PDSO10 |
| 封装： | MO-187CBA, MICRO, SOP-10 |
| 文件页数： | 12/24页 |
| 文件大小： | 742K |
| 代理商： | DS1390U-3 |
D
However, when V
CC
falls below V
PF
, the internal clock
registers are blocked from any access. If V
PF
is less
than V
BACKUP
, the device power is switched from V
CC
to V
BACKUP
when V
CC
drops below V
PF
. If V
PF
is
greater than V
BACKUP
, the device power is switched
from V
CC
to V
BACKUP
when V
CC
drops below
V
BACKUP
. The registers are maintained from the
V
BACKUP
source until V
CC
is returned to nominal levels.
See the
Functional Diagram
for the main elements of
these serial RTCs.
Oscillator Circuit
All four devices use an external 32.768kHz crystal. The
oscillator circuit does not require any external resistors
or capacitors to operate. Table 1 specifies several crys-
tal parameters for the external crystal, and Figure 7
shows a functional schematic of the oscillator circuit. If
a crystal is used with the specified characteristics, the
startup time is usually less than one second.
Clock Accuracy
The accuracy of the clock is dependent upon the accu-
racy of the crystal and the accuracy of the match
between the capacitive load of the oscillator circuit and
the capacitive load for which the crystal was trimmed.
Additional error is added by crystal frequency drift
caused by temperature shifts. External circuit noise
coupled into the oscillator circuit can result in the clock
running fast. Figure 8 shows a typical PC board layout
for isolation of the crystal and oscillator from noise.
Refer to
Application Note 58: Crystal Considerations
with Dallas Real-Time Clocks
for detailed information.
Low-Voltage SPI/3-Wire RTCs with
Trickle Charger
12
____________________________________________________________________
PARAMETER
Nominal Frequency
Series Resistance
Load Capacitance
SYMBOL
f
O
ESR
C
L
MIN
TYP
32.768
MAX
UNITS
kHz
k
pF
55
6
COUNTDOWN
CHAIN
X1
X2
CRYSTAL
C
L
1
C
L
2
RTC REGISTERS
DS139x
Table 1. Crystal Specifications*
*
The crystal, traces, and crystal input pins should be isolated
from RF generating signals. Refer to
Application Note 58:
Crystal Considerations for Dallas Real-Time Clocks
for addi-
tional specifications.
Figure 7. Oscillator Circuit Showing Internal Bias Network
LOCAL GROUND PLANE (LAYER 2)
CRYSTAL
GND
X2
X1
NOTE:
AVOID ROUTING SIGNAL LINES
IN THE CROSSHATCHED AREA
(UPPER LEFT QUADRANT) OF
THE PACKAGE UNLESS THERE IS
A GROUND PLANE BETWEEN THE
SIGNAL LINE AND THE DEVICE PACKAGE.
Figure 8. Layout Example
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相关代理商/技术参数 |
参数描述 |
|---|---|
| DS1390U-3+ | 功能描述:实时时钟 Low-V SPI/3-Wire With Trickle Charger RoHS:否 制造商:Microchip Technology 功能:Clock, Calendar. Alarm RTC 总线接口:I2C 日期格式:DW:DM:M:Y 时间格式:HH:MM:SS RTC 存储容量:64 B 电源电压-最大:5.5 V 电源电压-最小:1.8 V 最大工作温度:+ 85 C 最小工作温度: 安装风格:Through Hole 封装 / 箱体:PDIP-8 封装:Tube |
| DS1390U-3+T&R | 制造商:Maxim Integrated Products 功能描述:DS1390U-3 RTC 3V USOP T&R PB-FRE - Tape and Reel 制造商:Maxim Integrated Products 功能描述:IC RTC SPI 3WIRE W/CHRGR 10-MSOP |
| DS1390U-3+T&R | 功能描述:实时时钟 Low-V SPI/3-Wire With Trickle Charger RoHS:否 制造商:Microchip Technology 功能:Clock, Calendar. Alarm RTC 总线接口:I2C 日期格式:DW:DM:M:Y 时间格式:HH:MM:SS RTC 存储容量:64 B 电源电压-最大:5.5 V 电源电压-最小:1.8 V 最大工作温度:+ 85 C 最小工作温度: 安装风格:Through Hole 封装 / 箱体:PDIP-8 封装:Tube |
| DS1390U-33 | 功能描述:实时时钟 RoHS:否 制造商:Microchip Technology 功能:Clock, Calendar. Alarm RTC 总线接口:I2C 日期格式:DW:DM:M:Y 时间格式:HH:MM:SS RTC 存储容量:64 B 电源电压-最大:5.5 V 电源电压-最小:1.8 V 最大工作温度:+ 85 C 最小工作温度: 安装风格:Through Hole 封装 / 箱体:PDIP-8 封装:Tube |
| DS1390U-33/V+ | 制造商:MAXIM 制造商全称:Maxim Integrated Products 功能描述:Low-Voltage SPI/3-Wire RTCs with Trickle Charger |
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