Document: LT0273

MX4428 MXP Engineering / Technical Manual

 

 

MXP Technical Description

(i)

+VS

This is a switched version of "+V", which is switched OFF

 

 

when the loop supply falls below the voltage required for

 

 

correct operation of the MXP.

(ii)

40V ISO

A regulated, isolated 40V supply used to drive the Analogue

 

 

Loop circuitry and addressable devices.

(iii)

24V ISO

Derived from 40V ISO to power 24V relays.

(iv)

5V

Used to power the CPU and logic circuitry.

(v)

5VB

Used to power the RAM and PAL. Backed up by supercap

 

 

(C68).

Descriptions of the circuitry required to generate these power supplies follow.

7.2.3.1+VS Circuitry

The MXP is specified to operate over an MX4428 loop supply range of 17.0V to 30.0V. The MX4428 loop fault clearing technique relies on the fact that responders that are not powered up "look like" a high impedance (see Section 7.2.4 for details). The circuitry is therefore divided up into two sections, a (relatively) high current portion which becomes active only when adequate voltage is available, and a low current portion that is continuously powered up and whose sole purpose is to sense the loop voltage and control the enabling/disabling of the high current circuitry. Loop voltage sensing is performed by comparator U7:C and associated components which, in turn, operate power switch Q22 to feed +VS. Since the voltage regulator draws peak currents up to around 5A, a FET is used for Q22, which gives a low voltage drop for minimal control (gate) current.

D39, R12, R35, R113 ensure that +VS becomes active if the loop supply exceeds 17.0V, with R28, R110, D38 providing about 4V of hysteresis (i.e. once switched on +VS will stay switched on until the supply voltage drops below 13V).

7.2.3.240V ISO

The 40V ISO and 5V ISO supplies are produced using the switch mode power supply controller IC U10, FET Q17, and associated components. The circuit configuration is such that the circuit operates in flyback mode, energy being stored in L1 primary during Q17's ON period and transferred to the two secondary windings during the OFF period.

The current into the diode of optocoupler OC6 increases rapidly as the 40V ISO voltage passes through 40V (adjustable by means of VR1). The optocoupler OC6 controls the feedback to U10 pin 2 which adjusts the duty cycle of the current pulses into L1's primary and maintains regulation of 40V ISO.

R6 and C63 provide stability, essentially coupling the sawtooth from the internal oscillator to the comparator – input, thereby making the + input a much lower gain pulse width control than it would otherwise be. R107, R65, C38 provide over-current protection, while C34 defines the frequency of oscillation (approximately 80KHz). D41 and C77 provide a “soft start” circuit to reduce the current taken during the startup time.

7.2.3.324V ISO

The 40V ISO voltage is regulated by a linear regulator consisting of Q23, D40 and associated components. This supply is only required to supply a low current (about 30mA max) to drive relays. The reference diode (D40) used for the 24V supply is also used as the reference for the 40V supply.

Issue 1.5

24 March 2006

Page 7-5

Page 88 Page 90
Page 89
Image 89
Tyco MX4428 technical manual 3.1 +VS Circuitry, 3.2 40V ISO, 3.3 24V ISO
Page 88 Page 90

MX4428 specifications

The Tyco MX4428 is a cutting-edge device known for its robust performance in the realm of wireless communication and sensor acquisition. Tailored for applications in various sectors, the MX4428 is particularly well-suited for industrial automation, environmental monitoring, and smart city initiatives. With its advanced features, the device has gained tremendous popularity among engineers and developers looking for reliability and efficiency in data transmission.

One of the standout features of the MX4428 is its exceptional range, which can extend up to several kilometers under optimal conditions. This long-range capability ensures that data can be transmitted over vast distances without degradation in quality, making it ideal for remote monitoring applications. Additionally, the device operates on multiple frequency bands, providing flexibility in deployment based on specific regional requirements and regulatory guidelines.

The MX4428 utilizes a highly efficient radio protocol that enhances data throughput while reducing power consumption. This asymmetric data transmission method allows for low-duty cycle operation, extending battery life and autonomy. The device's energy efficiency is particularly beneficial in applications where frequent battery replacement would be impractical, such as in environmental sensors and agricultural monitoring systems.

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In summary, the Tyco MX4428 is a powerful and versatile device that boasts a combination of long-range communication, low power consumption, and comprehensive sensor integration capabilities. Its robust security features further enhance its appeal for critical applications across various industries. Whether for industrial, environmental, or smart city use cases, the MX4428 stands out as a reliable solution that meets the demands of modern wireless communication landscapes.
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