8-/4-/2-Channel,with ±10V, ±5V12-Bit,, and 0 to +5V Analog Input Ranges

Simultaneous-Sampling ADCsHowever, the new configuration does not take effectDigital Interface

until the next CONVST falling edge. At power-up allThe bidirectional parallel digital interface allows for settingchannels default active. Shutdown does not change thethe 8-bit configuration register (see the Configurationconfiguration register. The configuration register mayRegistersection) and reading the 12-bit conversionbe written to in shutdown. See the Channel Shutdownresult. The interface includes the following control signals:(CHSHDN) section for information about using the con-chip select (CS), read (RD), write (WR), end of conversionfiguration register for power saving.

(EOC), end of last conversion (EOLC), conversion start(CONVST), shutdown (SHDN), channel shutdown(CHSHDN), internal clock select (INTCLK/EXTCLK), andexternal clock input (CLK). Figures 6, 7, 8, 9, Table 2, andthe Timing Characteristicsshow the operation of the inter-face. D0–D7 are bidirectional, and D8–D11 are outputonly. 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 bitsin 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 thecorresponding input channel, while resetting any bitlow deactivates the corresponding channel. On thedevices with less than eight channels, some of the bitshave no function (Table 2).

To write to the configuration register, pull CSand WRlow, load bits D0 through D7 onto the parallel bus, andforce WRhigh. The data are latched on the rising edgeof WR(Figure 6). Write to the configuration register atany point during the conversion sequence. At power-up, write to the configuration register to select theactive channels before beginning a conversion.

Table 2. Configuration Register

______________________________________________________________________________________21

MAX1304–MAX1306/MAX1308–MAX1310/MAX1312–MAX1314