Rainbow-electronics MAX1083 Uživatelský manuál stáhnout pdf (Strana 18)

MAX1082/MAX1083

300ksps/400ksps, Single-Supply, 4-Channel,

Serial 10-Bit ADCs with Internal Reference

18 ______________________________________________________________________________________

Figure 11a. Full Power-Down Timing

REFADJ

1.22V

2.5mA

1.3mA OR 0.9mA

DIN

DD1

+ IV

DD2

REF

FULLPD

REDP

WAIT 1.2ms (7 x RC)

FULLPD

γ = RC = 17kΩ x 0.01µF

DUMMY CONVERSION

2.5V

2.5mA

0mA

2.5V

Figure 11b. FASTPD and REDP Timing

2.5V (ALWAYS ON)

2.5mA

DIN

DD1

+ IV

DD2

REF

REDP

REDP FASTPD

2.5mA

0.9mA

1.3mA

unipolar operation, and 1LSB = 2.44mV [(2.500V / 2) /

1024] for bipolar operation.

Layout, Grounding, and Bypassing

For best performance, use printed circuit (PC) boards;

wire-wrap boards are not recommended. Board layout

should ensure that digital and analog signal lines are

separated from each other. Do not run analog and digi-

tal (especially clock) lines parallel to one another, or

digital lines underneath the ADC package.

Figure 15 shows the recommended system ground

connections. Establish a single-point analog ground

(star ground point) at GND. Connect all other analog

grounds to the star ground. Connect the digital system

ground to this ground only at this point. For lowest-

noise operation, the ground return to the star ground’s

power supply should be low impedance and as short

as possible.

High-frequency noise in the V

DD1

power supply may

affect the high-speed comparator in the ADC. Bypass

the supply to the star ground with 0.1µF and 10µF

capacitors close to V

DD1

of the MAX1082/MAX1083.

Minimize capacitor lead lengths for best supply-noise

rejection. If the power supply is very noisy, a 10Ω resis-

tor can be connected as a lowpass filter (Figure 15).

High-Speed Digital Interfacing with QSPI

The MAX1082/MAX1083 can interface with QSPI using

the circuit in Figure 16 (CPOL = 0, CPHA = 0). This QSPI

circuit can be programmed to do a conversion on each of

the four channels. The result is stored in memory without

taxing the CPU, since QSPI incorporates its own microse-

quencer.

TMS320LC3x Interface

Figure 17 shows an application circuit to interface the

MAX1082/MAX1083 to the TMS320 in external clock

mode. The timing diagram for this interface circuit is

shown in Figure 18.

Use the following steps to initiate a conversion in the

MAX1082/MAX1083 and to read the results:

1) The TMS320 should be configured with CLKX

(transmit clock) as an active-high output clock and

1 2 ... 13 14 15 16 17 18 19 20 21 22 23 24

MAX1082/MAX1083 1

Komentáře k této Příručce

Žádné komentáře

Rainbow-electronics MAX1083 Uživatelský manuál Strana 18

Komentáře k této Příručce

Související produkty a manuály pro Senzory Rainbow-electronics MAX1083