ZHCSH77D June 2017 – May 2019 DAC8740H , DAC8741H
PRODUCTION DATA.
All of the devices in the DAC874xH family support a variety of clocking options in order to provide system flexibility and reduce overall current consumption in HART applications. The clocking options include: an internal oscillator (HART mode only), an external crystal oscillator, or an external CMOS clock. The selection of the clocking scheme is controlled by the XEN, CLK_CFG1, and CLK_CFG0 pins as described in Table 2.
The internal oscillator takes approximately 50 ms to start oscillating from when it is enabled. During this time period the device is unable to perform modulation or demodulation activities.
| XEN | CLK_CFG1 | CLK_CFG0 | CLKO | DESCRIPTION | MODE |
|---|---|---|---|---|---|
| 1 | 0 | 0 | No output | 3.6864-MHz CMOS clock connected at XTAL1 | HART |
| 1 | 0 | 1 | No output | 1.2288-MHz CMOS clock connected at XTAL1 | |
| 1 | 1 | 0 | No output | Internal oscillator enabled | |
| 1 | 1 | 1 | 1.2288-MHz output | Internal oscillator enabled, CLKO enabled | |
| 0 | 0 | 0 | No output | Crystal oscillator enabled | |
| 0 | 0 | 1 | 3.6864-MHz output | 3.6864-MHz crystal oscillator, CLKO enabled | |
| 0 | 1 | 0 | 1.8432-MHz output | 3.6864-MHz crystal oscillator, CLKO enabled | |
| 0 | 1 | 1 | 1.2288-MHz output | 3.6864-MHz crystal oscillator, CLKO enabled | |
| 1 | 0 | 0.5 | No output | 4-MHz CMOS clock connected at XTAL1 | FOUNDATION
Fieldbus and PROFIBUS PA |
| 1 | 1 | 0.5 | No output | 2-MHz CMOS clock connected at XTAL1 | |
| 0 | 0 | 0.5 | No output | 4-MHz crystal oscillator | |
| 0 | 1 | 0.5 | 4-MHz output | 4-MHz crystal oscillator, CLKO enabled |