DS87C530-QNL Maxim Integrated Products, DS87C530-QNL Datasheet - Page 23

• Manufacturer Part Number: DS87C530-QNL
• Description: IC MCU EPR/ROM W/RTC 33MZ 52PLCC
• Manufacturer: Maxim Integrated Products
• Series: 87Cr

Specifications of DS87C530-QNL

• Core Processor: 8051
• Core Size: 8-Bit
• Speed: 33MHz
• Connectivity: EBI/EMI, SIO, UART/USART
• Peripherals: Power-Fail Reset, WDT
• Number Of I /o: 32
• Program Memory Size: 16KB (16K x 8)
• Program Memory Type: OTP
• Ram Size: 1K x 8
• Voltage - Supply (vcc/vdd): 4.5 V ~ 5.5 V
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 52-LCC, 52-PLCC
• Processor Series: DS87C530
• Core: 8051
• Data Bus Width: 8 bit
• Data Ram Size: 1 KB
• Interface Type: UART
• Maximum Clock Frequency: 33 MHz
• Number Of Programmable I/os: 32
• Number Of Timers: 3
• Operating Supply Voltage: 4.5 V to 5.5 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: PK51, CA51, A51, ULINK2
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -
• Data Converters: -
• Other names: DS87C530QNL

DS87C530/DS83C530 EPROM/ROM Microcontrollers with Real-Time Clock
IDLE MODE
Setting the lsb of the Power Control register (PCON; 87h) invokes the Idle mode. Idle will leave internal
clocks, serial ports and timers running. Power consumption drops because the CPU is not active. Since
clocks are running, the Idle power consumption is a function of crystal frequency. It should be
approximately one-half the operational power at a given frequency. The CPU can exit the Idle state with
any interrupt or a reset. Idle is available for backward software compatibility. The system can now reduce
power consumption to below Idle levels by using PMM1 or PMM2 and running NOPs.
STOP MODE ENHANCEMENTS
Setting bit 1 of the Power Control register (PCON; 87h) invokes the Stop mode. Stop mode is the lowest
of a standard Stop mode is approximately 1 A
power state since it turns off all internal clocking. The I
CC
but is specified in the Electrical Specifications. The CPU will exit Stop mode from an external interrupt
or a reset condition. Internally generated interrupts (timer, serial port, watchdog) are not useful since they
require clocking activity. One exception is that a RTC interrupt can cause the device to exit Stop mode.
This provides a very power efficient way of performing infrequent yet periodic tasks.
The DS87C530/DS83C530 provide two enhancements to the Stop mode. As documented below, the
device provides a bandgap reference to determine Power-fail Interrupt and Reset thresholds. The default
state is that the bandgap reference is off while in Stop mode. This allows the extremely low-power state
mentioned above. A user can optionally choose to have the bandgap enabled during Stop mode. With the
bandgap reference enabled, PFI and Power-fail Reset are functional and are a valid means for leaving
Stop mode. This allows software to detect and compensate for a brownout or power supply sag, even
when in Stop mode.
In Stop mode with the bandgap enabled, I
will be approximately 50A compared with 1A with the
CC
bandgap off. If a user does not require a Power-fail Reset or Interrupt while in Stop mode, the bandgap
can remain disabled. Only the most power sensitive applications should turn off the bandgap, as this
results in an uncontrolled power-down condition.
The control of the bandgap reference is located in the Extended Interrupt Flag register (EXIF; 91h).
Setting BGS (EXIF.0) to a 1 will keep the bandgap reference enabled during Stop mode. The default or
reset condition is with the bit at a logic 0. This results in the bandgap being off during Stop mode. Note
that this bit has no control of the reference during full power, PMM, or Idle modes.
The second feature allows an additional power saving option while also making Stop easier to use. This is
the ability to start instantly when exiting Stop mode. It is the internal ring oscillator that provides this
feature. This ring can be a clock source when exiting Stop mode in response to an interrupt. The benefit
of the ring oscillator is as follows.
Using Stop mode turns off the crystal oscillator and all internal clocks to save power. This requires that
the oscillator be restarted when exiting Stop mode. Actual startup time is crystal-dependent, but is
normally at least 4ms. A common recommendation is 10ms. In an application that will wake up, perform
a short operation, then return to sleep, the crystal startup can be longer than the real transaction. However,
the ring oscillator will start instantly. Running from the ring, the user can perform a simple operation and
return to sleep before the crystal has even started. If a user selects the ring to provide the startup clock and
the processor remains running, hardware will automatically switch to the crystal once a power-on reset
interval (65,536 clocks) has expired. Hardware uses this value to assure proper crystal start even though
power is not being cycled.
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