MAX11162 datasheet(21/28 Pages) MAXIM

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MAX11162

16-Bit, 500ksps, +5V Unipolar Input,

SAR ADC, in Tiny 10-Pin µMAX

www.maximintegrated.com

Daisy-Chain Mode, No-Busy Indicator

The daisy-chain mode with no-busy indicator is ideally

suited for multichannel isolated applications that require

minimal wiring complexity. Simultaneous sampling of

multiple ADC channels is realized on a 3-wire serial interface

where data readback is analogous to clocking a shift

compatible digital host with corresponding timing given in

Figure 14.

The daisy-chain mode is engaged when the MAX11162

detects the low state on SDI at the rising edge of CNVST.

In this mode, CNVST is brought low and then high to trigger

the completion of the acquisition phase and the start of a

conversion. A low SCLK state on the rising edge of CNVST

signals to the internal controller that the no-busy indicator

will be output. When in chain mode, the SDO output is

driven active at all times.

When SDI and CNVST are both low, SDO is driven low,

thus engaging the daisy-chain mode of operations on the

downstream MAX11162 parts. For example, in Figure 13

part A has its SDI tied low so the chain mode of operation will

be selected on every conversion. When CNVST goes

low to trigger another conversion, part A’s SDO and

consequently part B’s SDI go low as well. On the next

CNVST rising edge both parts A and B will select the daisy-

chain mode interface.

When a conversion is complete, the MSB is presented onto

SDO, and the MAX11162 returns to the acquisition phase.

The remaining data bits, stored within the internal shift

edge. The SDI input of each ADC in the chain is used to

transfer conversion data from the previous ADC into the

internal shift register of the next ADC, thus allowing for data

to be clocked through the multichip chain on each SCLK

falling edge. Each ADC in the chain outputs its MSB data

first requiring 16 × N clocks to read back N ADCs.

In daisy-chain mode, the maximum conversion rate is

reduced due to the increased readback time. For instance,

with a 6ns digital host setup time and 3V interface, up to

Figure 13. Daisy-Chain Mode, No-Busy Indicator Connection Diagram

Figure 14. Daisy-Chain Mode, No-Busy Indicator Serial Interface Timing

DAISY-CHAIN MODE, NO BUSY INDICATOR SERIAL INTERFACE TIMING

DA15

SCLK

SDOA = SDIB

CNVST

tCONV

CONVERSION

ACQUISITION

DA14

DA13

DA1

DA0

tSCLKL

tSCLKH

tDSDO

tHSCKCNV

tSSCKCNV

SDOB

DB15

DB14

DB13

DB1

DB0

DA15

DA14

DA1

DA0

tSSDISCK

tHSDISCK

tCNVPW

SELECT NO

BUSY

OUTPUT

SELECT

CHAIN MODE

tCYC

tACQ

tSCLK

SDO

SDI

SCLK

CLK

DATA IN

DIGITAL HOST

CNVST

CONVERT

SDO

SDI

SCLK

CNVST

MAX11162

Device A

Device B

SDOA

SDOB

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