Rainbow-electronics MAX159 Bedienungsanleitung PDF herunterladen (Seite 13)

star-point (Figure 11) connecting the two ground sys-

tems (analog and digital). For lowest-noise operation,

ensure the ground return to the star ground’s power

supply is low impedance and as short as possible.

Route digital signals far away from sensitive analog and

reference inputs.

High-frequency noise in the power supply (V

) could

influence the proper operation of the ADC’s fast com-

parator. Bypass V

to the star ground with a network

of two parallel capacitors, 0.1µF and 1µF, located as

close as possible to the power supply pin of the

MAX157/MAX159. Minimize capacitor lead length for

best supply-noise rejection and add an attenuation

resistor (10Ω) if the power supply is extremely noisy.

MAX157/MAX159

+2.7V, Low-Power, 2-Channel,

108ksps, Serial 10-Bit ADCs in 8-Pin µMAX

______________________________________________________________________________________ 13

SCK

SDI

GND GND

I/O

SCLK

DOUT

CS/SHDN

MAX157

MAX159

PIC16/PIC17

CHID D9 D8 D7 D6

1 2 3 4 5 6 7 8 9 10111213141516

D5 D4 D3 D2 D1

HIGH-Z

DOUT*

CS/SHDN

SCLK

1ST BYTE READ 2ND BYTE READ

SAMPLING INSTANT

*WHEN CS/SHDN IS HIGH, DOUT = HIGH - Z

MSB

LSB

D0 S1 S0

Figure 10b. SPI Interface Timing Sequence with PIC16/17 in Master Mode (CKE = 1, CKP = 0, SMP = 0, SSPM3–SSPM0 = 0001)

Figure 10a. SPI Interface Connection for a PIC16/PIC17

Controller

CHID D9 D8 D7 D6

1 2 3 4 5 6 7 8 9 10111213141516

D5 D4 D3 D2 D1

HIGH-Z

DOUT

CS/SHDN

SCLK

SAMPLING INSTANT

*WHEN CS/SHDN IS HIGH, DOUT = HIGH - Z

MSB LSB

D0 S1 S0

Figure 9b. QSPI Interface Timing Sequence (CPOL = CPHA = 0)

+3V

GND+3V

POWER SUPPLIES

DGND+3V

GNDV

DIGITAL

CIRCUITRY

MAX157

MAX159

R* = 10Ω

1µF

0.1µF

* OPTIONAL FILTER RESISTOR

Figure 11. Power-Supply Bypassing and Grounding

1 2 ... 8 9 10 11 12 13 14 15 16

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