Cheap ADC

Adam Wang adam at sharism.cc
Sun Oct 3 21:43:21 EDT 2010


Hi,

I don't have clear vendor list of ADC chip from Asia now. So answer this
question is quite hard for me. Surely if anyone have alternatives pls
provide sources without doubts

Before we search other substitutions(same spec.) or similar parts but not
same spec.,
the criteria of choosing need to determine:

Fg.:
Checking the design guide first, like Microchip [1]
    a) a high-speed SAR converter? <= 100us
    b) Voice-Band Recording application? 60-70 dB of dynamic range, a medium
speed (50-200 ksps) SAR or delta-sigma converter would work in this
application.
    c) how many channels? 8 CHs with the same SAR?
        There's a MUX inside chip to work as fast switching that which
channel being chose(fast scanning) and sampled & held. That reflects its
cost.
    d) Resolution? 10 bit, 12 bit?
    e) with Low Temperature Drift? low standby current? (no need this due to
cheap ADC)
    f) Max. INL ± (LSB)? 1 or 2?
    g) SPI or I2C interface?

The facts are:

   More input channels more expensive.
   More resolutions more expensive.
   More Max Sample Rates more expensive.

Here's the comparison: check [2] out, (official volume pricing)

1, MCP3001, 10-bit, 200kSPS, 1 CH, 500 Max. Supply Current (µA), SPI, USD
1.22
2, MCP3008, 10-bit, 200kSPS, 8 CHs, 500 Max. Supply Current (µA), SPI, USD
1.58
3, MCP3021, 10-bit, 22  kSPS, 1 CH, 250 Max. Supply Current (µA), I2C, USD
1.02
4, MCP3201, 12-bit, 100kSPS, 1 CH, 400 Max. Supply Current (µA), SPI, USD
1.63

Currently I don't have an Asia chip vendor with manufacturing diverse ADCs
like Analog, TI or Microchip, so I think you may need to well-defined the
application/target first.

[1] ww1.microchip.com/downloads/en/devicedoc/21841a.pdf
[2]
http://www.microchip.com/ParamChartSearch/chart.aspx?branchID=11021&mid=10&lang=en&pageId=79
-- 
Best Regards
Adam Wang
http://www.nanonote.cc
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