Rainbow-electronics MAX1249 Uživatelský manuál stáhnout pdf (Strana 7)

MAX1248/MAX1249

+2.7V to +5.25V, Low-Power, 4-Channel,

Serial 10-Bit ADCs in QSOP-16

_______________________________________________________________________________________ 7

NAME FUNCTION

1 V

Positive Supply Voltage

2–5 CH0–CH3 Sampling Analog Inputs

6 COM

Ground reference for analog inputs. Sets zero-code voltage in single-ended mode. Must be stable to

±0.5LSB.

SHDN

Three-Level Shutdown Input. Pulling SHDN low shuts the MAX1248/MAX1249 down; otherwise, the

devices are fully operational. Pulling SHDN high puts the reference-buffer amplifier in internal compen-

sation mode. Letting SHDN float puts the reference-buffer amplifier in external compensation mode.

12 DOUT

Serial Data Output. Data is clocked out at SCLK’s falling edge. High impedance when CS is high.

11 DGND Digital Ground

9 REFADJ Input to the Reference-Buffer Amplifier. To disable the reference-buffer amplifier, tie REFADJ to V

8 VREF

Reference-Buffer Output/ADC Reference Input. Reference voltage for analog-to-digital conversion. In

internal reference mode (MAX1248 only), the reference buffer provides a 2.500V nominal output,

externally adjustable at REFADJ. In external reference mode, disable the internal buffer by pulling

REFADJ to V

16 SCLK

Serial Clock Input. Clocks data in and out of serial interface. In external clock mode, SCLK also sets

the conversion speed. (Duty cycle must be 40% to 60%.)

Active-Low Chip Select. Data will not be clocked into DIN unless CS is low. When CS is high, DOUT is

high impedance.

14 DIN Serial Data Input. Data is clocked in at SCLK’s rising edge.

13 SSTRB

Serial Strobe Output. In internal clock mode, SSTRB goes low when the MAX1248/MAX1249 begin the

A/D conversion and goes high when the conversion is completed. In external clock mode, SSTRB

pulses high for one clock period before the MSB decision. High impedance when CS is high (external

clock mode).

______________________________________________________________Pin Description

DGND

DOUT

LOAD

50pF

LOAD

50pF

DGND

DOUT

a) High-Z to V

and V

to V

b) High-Z to V

and V

to V

DGND

DOUT

LOAD

50pF

LOAD

50pF

DGND

DOUT

a) V

to High-Z b) V

to High-Z

Figure 1. Load Circuits for Enable Time Figure 2. Load Circuits for Disable Time

10 AGND Analog Ground

1 2 3 4 5 6 7 8 9 10 11 12 ... 23 24

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