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MAC-SA5X USER’S GUIDE
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2019 Microchip Technology Inc. DS50002938A-page 9
Chapter 1. Product Overview
1.1 MAC-SA5X OVERVIEW
The MAC is a source of stable output frequency. Because it relies on the Atomic reso-
nance of Rubidium Isotope 87 (87Rb) gas to generate the RF output, it is less suscep-
tible to instabilities produced from the mechanical and thermal stresses inherent in
Quartz oscillators, enabling superior mid- to long-term accuracy. This stability makes it
suitable as a holdover reference in GPS denied environments. Frequency errors can
be corrected by applying a digital command or external correction voltage to the MAC.
(See Frequency steering and
Section 3.2 “Analog Tuning” ). Frequency drift (Aging
rate) can also be corrected by implementing the 1PPS disciplining feature of the MAC.
When combined with a GNSS receiver, this feature allows the system designer to com-
bine the short-term stability of a Rb reference with the long-term stability of the GNSS,
approaching the performance of laboratory-grade Cesium Beam Tube frequency stan-
dards (see
Section 3.4 “1PPS Disciplining” ).
The Miniature Atomic Clock (MAC) SA5X is Microchip's seventh generation gas cell
atomic oscillator technology product. It was designed to accommodate a variety of tim-
ing applications as well as to replace several legacy Rubidium products (SA.22c, x72
and MAC-SA.3Xm). The footprint is compatible with the SA.3Xm, but with several
advancements in technology and features. Users of the previous generation (SA.3Xm)
can now expect improvements to frequency stability, warm-up time, input voltage
range, and operational temperature range. Additionally, 1PPS disciplining and USB
connections via a new embedded Molex™ connector allow greater design capabilities.
The 1PPS input allows users to quickly calibrate frequency and phase of the MAC to a
primary clock such as GPS, while the RF and 1PPS outputs provide highly stable hold-
over references.
FIGURE 1-1: The Miniature Atomic Clock (MAC) SA5X.