9.2.2 Detailed Design Procedure

The following items must be determined before starting design of a CDCDB803 socket:

• Output Enable Control Method

• SMBus address

9.2.2.1 Output Enable Control Method

The device provides an option to either use SMBus programmed registers (software) to control the outputs or by

using the hardware OE# pins. In case of using software to control the outputs, the hardware OE# pins can be left

floating as each of these pins have a pulldown to ground. Refer to Table 8-2 and the Register Maps section for

more information on programming the register.

When the user wants to control the outputs with the hardware OE# pins, they can do so for example by

connecting these pins to a GPIO controller and follow the Pin Configuration and Functions section to set the

outputs to HIGH/LOW. The bits OUT_EN_CLK7 to OUT_EN_CLK0 used to control the outputs are shown in

registers OECR1 (Table 8-7) and OECR2 (Table 8-8). These register bits are set to 1 by default to ensure that

the outputs are "software enabled" and their state is therefore set by hardware OE# pins.

9.2.2.2 SMBus Address

An SMBus address should be selected from the listed potential addresses in Table 8-1. The appropriate pullup or

pulldown resistor should be placed on the SADRx pins as indicated in the table. Ensure the SMBus address is

not already in use to avoid conflict.

9.2.3 Application Curves

Figure 6-1 in the Typical Characteristics section can be used as both an application curve and a typical

characteristics plot in this example.

The Figure 9-2 and Figure 9-3 show characterization data for the Output slew rate for various CAPTRIM codes

and across temperature. Customers can use these plots as reference for choosing the appropriate output slew

rate based on their system requirement.

.

Figure 9-2. Output Slew Rate vs. CAPTRIM Code

Temperature (qC)

120

100

80

60

40

20

0

-20

-40

-60

0

1

2

3

4

5

6

7

D002

0 - 3.3 V

1 - 3.3 V

2 - 3.3 V

3 - 3.3 V

4 - 3.3 V

5 - 3.3 V

6 - 3.3 V

7 - 3.3 V

8 - 3.3 V

9 - 3.3 V

10 - 3.3 V

11 - 3.3 V

12 - 3.3 V

13 - 3.3 V

.

Figure 9-3. Slew Rate Variation Across

Temperature for Different CAPTRIM Code

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CDCDB803

SNAS820 – AUGUST 2021

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