mobile | classic
Dataweek Electronics & Communications Technology Magazine

Follow us on:
Follow us on Facebook Share via Twitter Share via LinkedIn


Electronics Buyers' Guide

Electronics Manufacturing & Production Handbook 2019


Must you have that capacitor?
14 February 2001, Passive Components

When demand for the most common types of capacitors is stretching the world's supply, the use of sensible alternatives can avoid difficulties and may even save money. Murata explains further.

By far the most popular capacitors used are the smaller multilayer ceramic chips (MLCCs). There are many variations available and they are increasingly replacing film and tantalum dielectrics. The majority are used in decoupling and bypass applications, although there is a significant use in temperature compensating and other functions.

Recently, the main changes in MLCCs have been in C/V per unit volume so that the designer can now select a given C/V in a smaller package, for example, many of the values traditionally ordered in 1206 and 0805 sizes are now in 0603 or even 0402. Volume users are moving to these sizes so there will be more of them when delivery schedules get tight.

Difficulties can be minimised at the design stage by using the smaller sizes and more flexible definitions of MLCCs for general applications, with particular reference to the dielectric and voltage ratings (VR) chosen. For example, why specify only one VR? Most circuits today run at something under 10 V. It would be reasonable to specify a 10 or 16 V MLCC, but why not specify 10, 16, 25 and 50 V where they are available in the size required?

MLCCs are often specified at unnecessarily high VRs. Unlike many other dielectrics, the VR of an MLCC is the maximum voltage at which it can be run continuously within the operating temperature range. There is no need for a safety margin to avoid punching a hole in the dielectric at RV +5%, because the breakdown voltage of an MLCC is well above the operating voltage.

The same principle applies to a lesser degree to tolerance. High K dielectrics do have temperature, voltage and frequency characteristics and the selection of these materials indicates an application that will tolerate them. This being the case, relaxing or tightening the tolerance to allow use of an alternative may well be acceptable.

In decoupling and bypass applications, the capacitance value is rarely critical. This suggests that similar but different dielectrics could safely be used. For example in a benign environment, why specify only an X7R dielectric (-55 to 125°C)? Why not consider Y5V and Z5U. They have a higher dissipation factor and change more with temperature, but why in signal lines where temperature is not changing very much and the value is not critical?

In applications calling for stability or temperature compensation, the situation is different but there are still opportunities to be more flexible.

The comments above about voltage rating still apply. For absolute stability COG (±030 ppm/°C) has to be the answer but perhaps COH (±060 ppm/°C) would suffice on some occasions?

With tolerance, in stable circuits there is a tendency to select the tightest available. This may be necessary, but in view of all the other variables, is it always the case?

Table 1 shows some of the dielectric alternatives you might consider at the design stage or when a specified part is not readily available. Clearly, changing between X7R, X5R, B and R dielectrics will have a negligible effect unless operating at the extremes of temperature and there is little to choose between Y5V and Z5U.

Table 1. Some dielectric alternatives
Table 1. Some dielectric alternatives

These are just examples of what might be done at the design stage or when there is a problem. Should you require assistance, contact the local Murata distributor.

Some of the alternatives for three popular devices are shown in Table 2. These are not the limits of the size/value ranges, they are just options for these values.

Table 2. Alternatives for three popular devices
Table 2. Alternatives for three popular devices

Supplied By: Avnet South Africa
Tel: +27 11 319 8600
Fax: +27 11 319 8650
Supplied By: Communica
Tel: +27 12 657 3500
Fax: +27 12 657 3550
Supplied By: EBV Electrolink
Tel: +27 11 236 1900
Fax: +27 11 236 1913
  Share on Facebook Share via Twitter Share via LinkedIn    

Further reading:

  • Mixed-signal MCUs for digital power
    26 June 2019, EBV Electrolink, DSP, Micros & Memory
    Targeted at advanced digital power applications and consumer and industrial appliances, the new STM32G4 microcontrollers (MCUs) introduce two new hardware mathematical accelerators to boost processing ...
  • eSPI-to-LPC bridge
    26 June 2019, Avnet South Africa, Computer/Embedded Technology
    Microchip Technology’s new ECE1200 bridge allows developers to implement the eSPI standard in boards with legacy LPC connectors and peripherals. Product longevity is critical in industrial computing ...
  • Designing certified power solutions for LED lighting
    26 June 2019, Avnet South Africa, Power Electronics / Power Management
    LED lighting has become the product of choice in all types of environments, from domestic to industrial through to specialist areas such as stage lighting. The combination of efficiency in terms of lumens ...
  • Automotive smart hub ICs
    26 June 2019, Avnet South Africa, Telecoms, Datacoms, Wireless, IoT
    Microchip Technology has added new single-port USB smart hub ICs to its family of USB automotive products. The USB4912 and the USB4712 can be used to add a single port under the radio, in the centre console ...
  • Consumer grade power inductors
    26 June 2019, Electrocomp, Passive Components
    Bourns is introducing the Model SRP7028C, SRP1038C and SRP1770C high-current shielded power inductor series, designed to meet today’s high current density requirements in various types of consumer electronics ...
  • High-current shielded power inductors
    26 June 2019, Electrocomp, Passive Components
    The inductive components product line at Bourns has created the Model SRP5050FA and Model SRP7030CA high-current shielded power inductor series, designed to meet today’s high current density requirements ...
  • Automotive switching regulator
    26 June 2019, EBV Electrolink, Power Electronics / Power Management
    The STMicroelectronics A7987 automotive switching regulator has a wide input voltage range that allows use in trucks and buses, and an adjustable output voltage that ensures flexibility and stable performance ...
  • Shielded power inductors
    26 June 2019, RF Design, Passive Components
    High-temperature power inductors from Coilcraft are available with inductance values from 22 to 47 µH, current ratings up to 5,5 A, and low direct current resistance (DCR). The inductors in the XAL7050 ...
  • Flash memories with embedded MAC addresses
    26 June 2019, Avnet South Africa, DSP, Micros & Memory
    Microchip Technology’s SST26VF Serial Quad I/O (SQI) 3 V Flash family is the industry’s first NOR Flash devices to offer integrated MAC address options. Pre-programmed with EUI-48 and EUI-64 addresses, ...
  • Three-phase gate driver
    26 June 2019, EBV Electrolink, Power Electronics / Power Management
    The STMicroelectronics STDRIVE601 three-phase gate driver for 600 V N-channel power MOSFETs and IGBTs provides enhanced ruggedness against negative voltage spikes down to -100 V and responds to logic ...
  • Passive RFID using UHF delivers long-range benefits in the IoT
    29 May 2019, Avnet South Africa, This Week's Editor's Pick, Telecoms, Datacoms, Wireless, IoT
    In order to support the use of UHF RFID as an IoT solution, a global alliance was formed in 2014 by Google, Intel, Impinj, Smartrac and AIM.
  • Wi-Fi and Bluetooth module
    29 May 2019, Avnet South Africa, Telecoms, Datacoms, Wireless, IoT
    Murata Manufacturing has collaborated with Cypress Semiconductor to develop the Type 1LV (CYW43012) low-power, small form factor Wi-Fi and Bluetooth module. This product is designed to improve battery ...

Technews Publishing (Pty) Ltd
1st Floor, Stabilitas House
265 Kent Ave, Randburg, 2194
South Africa
Publications by Technews
Dataweek Electronics & Communications Technology
Electronics Buyers’ Guide (EBG)

Hi-Tech Security Solutions
Hi-Tech Security Business Directory

Motion Control in Southern Africa
Motion Control Buyers’ Guide (MCBG)

South African Instrumentation & Control
South African Instrumentation & Control Buyers’ Guide (IBG)
Terms & conditions of use, including privacy policy
PAIA Manual


    Classic | Mobile

Copyright © Technews Publishing (Pty) Ltd. All rights reserved.