ALD500/ALD523D A/D Chipset FAQ


1. What is the Advanced Linear Devices (ALD) chipset?

The ALD A/D chipset consists of a dual-slope analog processor front-end chip and a digital controller chip. The ALD500 or the ALD500R is the analog chip and the ALD523D is the digital chip. The two CMOS chips are designed to work with multi-line character display modules.

2. Who can use this chipset?

The chipset is primarily intended for precision embedded A/D converter applications, where a digital readout of greater than 4-1/2 digits is required. Engineers can dramatically shorten their design cycle from 1-2 man-years to 1-2 man-weeks with this chip set.

3. In what applications can I best utilize this chipset?

Embedded applications requiring multiline character display readout of precision analog voltages with resolutions down to 1 microvolt. Examples include digital voltmeters, temperature gauges and weigh scales.

4. What are its unique features?

  • High resolution (up to 18-bits with sign and overrange bit), low noise conversions
  • High stability and accuracy - Cost saving (project labor cost, component count, component cost, board space and power)
  • ALD523D is a preprogrammed microprocontroller that works with most multi-line display modules up to 2 lines x 16 characters
  • Simple to use and calibrate

5. Why use the ALD500/ALD523D chipset instead of discrete components?

Much shorter design time. The chip set offers a complete monolithic solution that has undergone many hours of test and evaluation for stability and guaranteed performance. In most cases, the design can be fully implemented in 1-2 weeks.

6. What are the advantages of dual-slope integrating Analog Processors?

The integrating technique inherently filters out external noise signals, especially high voltage spikes and other power line 50/60 cycle related noise. Dual slope integrating A/D converters also offer several key performance advantages:
  • Repeatable results in the presence of high frequency noise (relative to the measurement period).
  • Use of time to quantize the answer, resulting in extremely small non-linearity errors and no possibility of missing output codes
  • Very good rejection of frequencies whose periods are an integral multiple of the measurement period
  • Smaller footprint and more cost-effective

7. Is this development better than the discrete design?

Answer already addressed in question 5.

8. What is the one single key benefit of using this chipset to control multiline character display modules?

The ALD chipset eliminates all the hassle of interfacing an A/D converter with a discrete digital controller whose output is formatted to communicate with conventional LCD and VFD multiline character display modules. ALD's digital controller chip (ALD523D), performs a multitude of microprocessor functions in a single chip, which is already compatible with most industry standard HD44780 display driver chips.

9. Is the chipset more accurate than like products currently available?

The ALD chipset offers higher resolution conversion -- up to 18-bits plus sign and overrange bit. The past chips have a maximum of 4½ digits for display. This chip set can do 4½, 5½ and 6½ digits plus a variety of displays of units in alphanumeric characters.

10. Would I want to use the chipset for portable voltmeter applications?

Yes, considering the resolution and the low power requirements, this chipset may be an excellent choice for a dedicated portable field application.

11. What kind of A/D converter is the ALD500 / ALD500R?

The ALD500 is an 18-bit dual slope integrating analog processor that performs the analog functions of an A/D converter. The ALD500R is an ALD500 with a precision on-chip voltage reference. These converters feature auto-zero and dual polarity (+/-) measurements with automatic polarity detection.

12. What is the full-scale analog input range?

The full-scale analog input range is +/-2.00000VDC with a linearity of 0.005%, when the analog chip is operated from a power supply as low as a 3.8V. With a regulated power supply, an input range up to +/-3.50000VDC is possible. With proper front-end signal conditioning circuitry, the ALD500 / ALD500R can accommodate virtually any input signal that can be converted into a DC voltage within the range specified above.

13. What character display modules have been tested with the chipset to know if it works with more than just one manufacturer?

The digital chip, ALD523D is designed to interface with a variety of LCD/VFD multi-line alphanumeric display modules that have 2 lines x 16 characters displays, and contain industry standard HD44780 or equivalent display controller with column driver.

14. What operating temperature grades are available?

The commercial grade version operates from 0°C to 70°C. There are industrial and military grades available as well.

15. A PC is required for setup and calibration -- is this a one time procedure?

Yes, after completing the necessary calibration and setup process, the computer can be disconnected and the chipset can be operated as a stand-alone component

16. How will the power down be helpful to the operation?

Both IC chips of the chipset can be put into a power-down mode to save power in battery operated applications.

17. What are the different modes used for?

Mode A is used for voltmeters that require a voltage reference. When ordering, you would want to order the ALD500R. (The R designates voltage reference.) Mode B selection would be used for the ratiometric measurement applications, such as in the case of a weigh scale. Here there is no need for a voltage reference so the ALD500 can be used. In Mode C -- display only, you would not have a requirement for the A/D front-end chip assuming that another means is available for inputting a serial data stream that is compatible with the ALD523D

18. If the maximum display range for the character display module is 7 digits and 32 characters. What was the original upper limit before the digital ALD523D chip was introduced?

4½ digits only and no character display.

19. How do I get started?

We suggest our Design Starter Kit that gives you several chip sets and a full array of other electronic support components -- everything you need to evaluate the chip set. The only thing you need to supply is the power supply, PC and character display module.

20. What is included in the kit?

Download the attachment MB203Kit for details.

21. How do I obtain samples for evaluation purposes?

We strongly recommend purchasing a Design Starter Kit, which includes PC software, schematics and documentation. These are available by contacting the manufacturer directly.

22. How much does the Design Kit cost?

For price and availability, please e-mail

23. Once I invest in parts and shipping for the Design Kit, and then want to build a second unit, how much do I have to spend in parts?

The Design Starter Kit contains sufficient quantities to build up 2 prototypes. You will have the software and instructions from your starter kit. The rest of the other hardware parts can be purchased from any electronics distributor or outlet. They are generic parts available from a number of well-known manufacturers.
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