Rainbow-electronics MAX1314 Bedienungsanleitung PDF herunterladen (Seite 21)

MAX1304–MAX1306/MAX1308–MAX1310/MAX1312–MAX1314

8-/4-/2-Channel, 12-Bit, Simultaneous-Sampling ADCs

with ±10V, ±5V, and 0 to +5V Analog Input Ranges

______________________________________________________________________________________ 21

Applications Information

Digital Interface

The bidirectional parallel digital interface allows for setting

the 8-bit configuration register (see the Configuration

result. The interface includes the following control signals:

chip select (CS), read (RD), write (WR), end of conversion

(EOC), end of last conversion (EOLC), conversion start

(CONVST), shutdown (SHDN), channel shutdown

(CHSHDN), internal clock select (INTCLK/EXTCLK), and

external clock input (CLK). Figures 6, 7, 8, 9, Table 2, and

the Timing Characteristics show the operation of the inter-

face. D0–D7 are bidirectional, and D8–D11 are output

only. D0–D11 go high impedance when RD = 1 or CS = 1.

Configuration Register

Enable channels as active by writing to the configura-

tion register through I/O lines D0–D7 (Table 2). The bits

in the configuration register map directly to the chan-

nels, with D0 controlling channel zero, and D7 control-

ling channel seven. Setting any bit high activates the

corresponding input channel, while resetting any bit

low deactivates the corresponding channel. On the

devices with less than eight channels, some of the bits

have no function (Table 2).

To write to the configuration register, pull CS and WR

low, load bits D0 through D7 onto the parallel bus, and

force WR high. The data are latched on the rising edge

of WR (Figure 6). Write to the configuration register at

any point during the conversion sequence. At power-

up, write to the configuration register to select the

active channels before beginning a conversion.

However, the new configuration does not take effect

until the next CONVST falling edge. At power-up all

channels default active. Shutdown does not change the

configuration register. The configuration register may

be written to in shutdown. See the Channel Shutdown

(CHSHDN) section for information about using the con-

figuration register for power saving.

Table 2. Configuration Register

BIT/CHANNEL

PART

NUMBER

STATE

D0/CH0 D1/CH1 D2/CH2 D3/CH3 D4/CH4 D5/CH5 D6/CH6

D7/CH7

ON 1 1111111

MAX1304

MAX1308

MAX1312

OFF 0 0 0 0 0000

ON 1 111XXXX

MAX1305

MAX1309

MAX1313

OFF 0 000XXXX

ON 1 1 X X XXXX

MAX1306

MAX1310

MAX1314

OFF 0 0 X X XXXX

X = Don’t care (must be 1 or 0).

D0–D7

DATA-IN

CONVST

CONFIGURATION

WRL

CTW

DTW

WTD

WTC

Figure 6. Write Timing

1 2 ... 16 17 18 19 20 21 22 23 24 25 26 ... 35 36

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