参数资料
型号: DS1374C-3#
厂商: Maxim Integrated Products
文件页数: 18/18页
文件大小: 0K
描述: IC RTC I2C W/CHARGER 16-SOIC
产品培训模块: Lead (SnPb) Finish for COTS
Obsolescence Mitigation Program
标准包装: 45
类型: 二进制计数器
特点: 警报器,方波输出,涓流充电器,监视计时器
时间格式: 二进制
数据格式: 二进制
接口: I²C,2 线串口
电源电压: 2.7 V ~ 3.3 V
电压 - 电源,电池: 1.3 V ~ 3.7 V
工作温度: -40°C ~ 85°C
安装类型: 表面贴装
封装/外壳: 16-SOIC(0.295",7.50mm 宽)
供应商设备封装: 16-SOIC W
包装: 管件
Detailed Description
The DS1374 is a real-time clock with an I2C serial inter-
face. It provides elapsed seconds from a user-defined
starting point in a 32-bit counter (Figure 4). A 24-bit
counter can be configured as either a watchdog
counter or an alarm counter. An on-chip oscillator cir-
cuit uses a customer-supplied 32.768kHz crystal to
keep time. A power-control circuit switches operation
from VCC to VBACKUP and back when power on VCC is
cycled. The oscillator and counters continue to operate
when powered by either supply. If a rechargeable
backup supply is used, a trickle charger can be
enabled to charge the backup supply while VCC is on.
Oscillator Circuit
The DS1374 uses 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. Figure 5 shows a
functional schematic of the oscillator circuit. The startup
time is usually less than 1 second when using a crystal
with the specified characteristics.
Clock Accuracy
Clock accuracy is dependent upon the accuracy 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 tempera-
ture shifts. External circuit noise coupled into the oscilla-
tor circuit can result in the clock running fast. Figure 6
shows a typical PC board layout for isolating the crystal
and oscillator from noise. Refer to
Application Note 58:
Crystal Considerations with Dallas Real-Time Clocks for
detailed information.
DS1374C Only
The DS1374C integrates a standard 32,768Hz crystal
into the package. Typical accuracy at nominal VCC and
25°C is approximately 10ppm. See
Application Note 58
for information about crystal accuracy vs. temperature.
DS1374
I2C, 32-Bit Binary Counter Watchdog RTC with
Trickle Charger and Reset Input/Output
_____________________________________________________________________
9
COUNTDOWN
CHAIN
X1
X2
CL1
CL2
CRYSTAL
RTC
REGISTERS
DS1374
Figure 5. Oscillator Circuit Showing Internal Bias Network
LOCAL GROUND PLANE (LAYER 2)
NOTE: AVOID ROUTING SIGNALS IN THE CROSSHATCHED AREA (UPPER LEFT-HAND
QUADRANT) OF THE PACKAGE UNLESS THERE IS A GROUND PLANE BETWEEN THE
SIGNAL LINE AND THE PACKAGE.
CRYSTAL
GND
X2
X1
Figure 6. Layout Example
PARAMETER
SYMBOL
MIN
TYP
MAX
UNITS
Nominal
Frequency
fO
32.768
kHz
Series
Resistance
ESR
45
k
Ω
Load
Capacitance
CL
6pF
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.
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DS1374C-33- 制造商:MAXIM 制造商全称:Maxim Integrated Products 功能描述:I2C, 32-Bit Binary Counter Watchdog RTC with Trickle Charger and Reset Input/Output