參數(shù)資料
型號: DS83C530-QCL
廠商: MAXIM INTEGRATED PRODUCTS INC
元件分類: Microcontroller
英文描述: 8-BIT, MROM, 33 MHz, MICROCONTROLLER, PQCC52
封裝: PLASTIC, LCC-52
文件頁數(shù): 4/45頁
文件大小: 649K
代理商: DS83C530-QCL
DS87C530/DS83C530 EPROM/ROM Microcontrollers with Real-Time Clock
12 of 45
12.5pF crystal uses more power, giving a shorter battery backed life, but produces a more robust
oscillator. Bit 6 in the RTC Trim register (TRIM; 96h) must be programmed to specify the crystal type
for the oscillator. When TRIM.6 = 1, the circuit expects a 12.5pF crystal. When TRIM.6 = 0, it expects a
6pF crystal. This bit will be nonvolatile so these choices will remain while the backup source is present.
A guard ring (connected to the RTC ground) should encircle the RTCX1 and RTCX2 pins.
Backup Energy Source
The DS87C530/DS83C530 use an external energy source to maintain timekeeping and SRAM data
without VCC. This source can be either a battery or 0.47F super cap and should be connected to the VBAT
pin. The nominal battery voltage is 3V. The VBAT pin will not source current. Therefore, a super cap
requires an external resistor and diode to supply charge.
The backup lifetime is a function of the battery capacity and the data retention current drain. This drain is
specified in the electrical specifications. The circuit loads the VBAT only when VCC has fallen below VBAT.
Thus the actual lifetime depends not only on the current and battery capacity, but also on the portion of
time without power. A very small lithium cell provides a lifetime of more than 10 years.
Figure 3. Internal Backup Circuit
IMPORTANT APPLICATION NOTE
The pins on the DS87C530/DS83C530 are generally as resilient as other CMOS circuits. They have no
unusual susceptibility to electrostatic discharge (ESD) or other electrical transients. However, no pin on
the DS87C530/DS83C530 should ever be taken to a voltage below ground. Negative voltages on any
pin can turn on internal parasitic diodes that draw current directly from the battery. If a device pin is
connected to the “outside world” where it may be handled or come in contact with electrical noise,
protection should be added to prevent the device pin from going below -0.3V. Some power supplies can
give a small undershoot on power-up, which should be prevented. Application Note 93: Design
Guidelines
for
Microcontrollers
Incorporating
NV
RAM
discusses
how
to
protect
the
DS87C530/DS83C530 against these conditions.
MEMORY RESOURCES
Like the 8051, the DS87C530/DS83C530 use three memory areas. The total memory configuration of the
device is 16kB of ROM, 1kB of data SRAM and 256 bytes of scratchpad or direct RAM. The 1kB of data
相關(guān)PDF資料
PDF描述
DS87C530-KCL 8-BIT, OTPROM, 33 MHz, MICROCONTROLLER, CQCC52
DTA-03D-1.5-TA-P POSITION, LINEAR SENSOR-AC, -3-3mm
DTA-01D-3-SA-P POSITION, LINEAR SENSOR-AC, -1-1mm
DTA-03D-1.5-CA-H POSITION, LINEAR SENSOR-AC, -3-3mm
DTA-03D-3-TA-W POSITION, LINEAR SENSOR-AC, -3-3mm
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