Microchip ATmegaS64M1 Handleiding


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 2020 Microchip Technology Inc. DS00003657A-page 1
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INTRODUCTION
This application note lists the Vectron high-reliability oscillator model numbers that have been characterized for use as
the External Clock of the ATmegaS64M1 series radiation tolerant microcontrollers. These oscillators are the only rec-
ommended external frequency sources for use as the ATmegaS64M1 External Clock. While other suppliers may offer
clocks that meet the specifications, they are not approved reference designs by Microchip, and, as such, the user must
complete his or her own qualification and analysis for fitness of use.
RECOMMENDED OSCILLATORS
The ATmegaS64M1 has three clock source options. This application note specifically addresses the external crystal
oscillators that are recommended for use with the External Clock. Two oscillator frequencies, 4 MHz and 8 MHz, are
recommended in the application note, though any frequency below 8 MHz may be used per Table 30-4 of the
ATmegaS64M1 data sheet. Four different reliability levels of the microcontroller are available. For each of these reliabil-
ity levels, the customer needs to ensure that the corresponding reliability level of the crystal oscillator is correctly spec-
ified to match the application. model numbers are defined in Eight individual oscillator Table 1 (one for each combination
of frequency and reliability level). These oscillators are directly coupled to the XTAL1 pad.
The models chosen are the most cost-effective solutions that meet the requirements of ATmegaS64M1 and the required
reliability level. The 1157 series oscillators recommended are from the Vectron Hi-Rel Oscillator standard OS-68338. All
the devices listed are 3.3V, CMOS, surface mount, 7 mm x 5 mm, ceramic leadless chip carrier oscillators. The subse-
quent paragraphs after Table 1 are provided for reference and compliance purposes.
TABLE 1: RECOMMENDED VECTRON HIGH-RELIABILITY OSCILLATOR MODELS AT TWO
EXTERNAL CLOCK FREQUENCIES
MCU Model Reliability Level External Clock Frequency Oscillator Model Number
ATmegaS64M1-KH-E Prototype (-E) 4 MHz 1157D4M00000BX
ATmegaS64M1-KH-MQ QML-Q equivalent 4 MHz 1157B4M00000BE
ATmegaS64M1-KH-SV QML-V equivalent 4 MHz 1157R4M00000BS
ATmegaS64M1-MA-HP HiREL Plastic 4 MHz 1157C4M00000BB
ATmegaS64M1-KH-E Prototype (-E) 8 MHz 1157D8M00000BX
ATmegaS64M1-KH-MQ QML-Q equivalent 8 MHz 1157B8M00000BE
ATmegaS64M1-KH-SV QML-V equivalent 8 MHz 1157R8M00000BS
ATmegaS64M1-MA-HP HiREL Plastic 8 MHz 1157C8M00000BB
Crystal Oscillators for ATmegaS64M1 Radiation Tolerant
Microcontroller External Clock Input
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DS00003657A-page 2  2020 Microchip Technology Inc.
COMPARISON OF ATMEGAS64M1 QUALITY FLOW REQUIREMENTS VS. OS-68338
SCREENING AND PEDIGREES
Due to differences in the requirements listed in MIL-PRF-38535 (for radiation hardened electronics) and MIL-PRF-
55310 (for crystal oscillators), exact matches in quality flow vs. screening levels and component pedigrees are not avail-
able. Table 2 summarizes available quality flows for the ATmegaS64M1 radiation tolerant microcontroller, and the rec-
ommended corresponding screening and pedigree levels for OS-68338 oscillators. Customers are encouraged to
review applicable specifications for mission critical applications to ensure full compliance.
COMPARISON OF ATMEGAS64M1 ELECTRICAL REQUIREMENTS VS. OS-68338
ELECTRICAL SPECIFICATIONS
Electrical performance requirements for the External Clock oscillator are defined in Table 30-2 and Table 30-3 of the
ATmegaS64M1 data sheet. Additional requirements have been derived from customer use cases. These requirements
are listed in Table 3, along with the corresponding electrical parameter specification from OS-68338.
TABLE 2: ATMEGAS64M1 QUALITY FLOW REQUIREMENTS VS. OS-68338 OSCILLATOR
SCREENING AND PEDIGREES
MCU Quality Flow Oscillator
Screening
Oscillator Component
Pedigree Description
Prototype (-E) X D
Engineering Model Hardware using high reliability
design with commercial grade components and non-
swept quartz.
QML-Q equivalent E B Military Grade Hardware using high reliability design
with military grade components and swept quartz.
QML-V equivalent S R Space Grade Hardware with 100 kRad die, space
grade components, and swept quartz.
Hirel Plastic (-HP) B C Military grade die and plastic packaging. Oscillator
uses military grade components and non-swept quartz.
TABLE 3: ELECTRICAL COMPLIANCE MATRIX FOR THE EXTERNAL CLOCK OSCILLATOR
Specification ATmegaS64M1 Microcontroller
Requirement OS-68338 Oscillator Specification
Operating Temperature –55°C to +125°C –55°C to +125°C
20-year Total Stability (Note 1) Not Defined ±100 ppm
Supply Voltage (VS) 3.3VDC 3.3VDC
Supply Voltage Tolerance ±0.3VDC ±0.33VDC
Voltage Low Logic Min. –0.5V 0V
Voltage Low Logic Max. VS x 0.1 VS x 0.1
Voltage High Logic Min. VS x 0.8 VS x 0.9
Voltage High Logic Max. VS + 0.5V VS
Duty Cycle 40% to 60% 45% to 55%
Rise and Fall Time Max. 1600 ns 5 ns
Total Ionized Dose 30 kRad 100 kRad
Single Event Latch-Up 62.5 MeV-cm2/mg 120 MeV-cm2/mg
Note 1: The ATmegaS64M1 data sheet does not specify a frequency stability requirement for the reference oscil-
lators. The recommended oscillators in this application note will maintain a fractional frequency error of
±100 ppm under all conditions for a 20 year operational life. Table 4 provides details on the frequency
budget. Note that while OS-68338 specification lists ±5 ppm for first-year aging, and ±2 ppm/year after
year one, due to the logarithmic nature of the aging curves, oscillators will comply with ±31 ppm total
aging over 20 years.
 2020 Microchip Technology Inc. DS00003657A-page 3
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ENCLOSURE OPTIONS
OS-68338 offers multiple enclosure options. The 1157 enclosure chosen for this application note, a surface mountable,
7 mm x 5 mm, ceramic leadless chip carrier, is the lowest cost solution in OS-68338. Other enclosures may be chosen
based on mission profiles, customer assembly and manufacturing guidelines, and customer quality requirements.
SUMMARY
The OS-68338 oscillators listed in Table 1 have been characterized and are recommended for use as the External Clock
for the ATmegaS64M1 radiation tolerant microprocessor. The oscillators meet all required performance parameters per
the ATmegaS64M1 data sheet and expected use cases. The oscillators are rated to similar radiation levels as the micro-
controller. Multiple alternate enclosure options are available and alternate frequencies below 8 MHz can be provided.
REFERENCES
OS-68838 Oscillator Specification:
https://www.vectron.com/products/military/xo/os68338.pdf
ATmegaS64M1 Radiation Tolerant Microcontroller Data Sheet:
http://ww1.microchip.com/downloads/en/DeviceDoc/ATmegaS64M1_datasheet_ds60001506b.pdf
TABLE 4: FREQUENCY STABILITY OF OS-68338 OSCILLATORS
Parameter Specification Maximum
Initial accuracy at +23°C ±15 ppm
Frequency Temperature Stability from +23°C reference ±50 ppm
Frequency vs. Voltage Tolerance ±4 ppm
20-year aging (including 100 kRad TID effects) ±31 ppm
Total cumulative frequency error for 20-year life ±100 ppm


Product specificaties

Merk: Microchip
Categorie: Niet gecategoriseerd
Model: ATmegaS64M1

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