Maxim DS1863 User Manual

Maxim > App Notes > DIGITAL POTENTIOMETERS

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Keywords: DS1863

APPLICATION NOTE 4052

May 25, 2007

Quick Reference Guide to the DS1863 Memory Map

Abstract: The DS1863 burst-mode PON controller with integrated monitoring capabilities has programming options to
configure the alarms, warnings, lookup tables, and other functions. This programmability necessitates a large register
memory map. This application note provides an outline of the register map, which is convenient when programming
the device.

Memory Map of the DS1863

The DS1863 features six separate memory tables that are internally organized into eight byte rows (Figure 1).

1. The Lower Memory is addressed from 00h to 7Fh. It contains alarm and warning thresholds, flags, masks,
several control registers, password entry area (PWE), and the Table Select byte.

2. Table 01h primarily contains user EEPROM (with PW1 level access) and some alarm and warning status bytes.

3. Table 02h is a multifunction space that contains configuration registers, scaling and offset values, passwords,
interrupt registers, and miscellaneous control bytes.

4. Table 03h is strictly user EEPROM that is protected by a PW2-level password.

5. Table 04h contains a temperature-indexed lookup table (LUT) for controlling the modulation voltage. The
modulation LUT can be programmed in 2°C increments over the -40°C to +102°C range. Access to this register
is protected by a PW2-level password.

6. Table 05h contains another LUT, which allows the APC set point to change as a function of temperature to
compensate for Tracking Error (TE). This TE LUT has 36 entries that determine the APC setting in 4°C windows
between -40°C to +100°C. Access to this register is protected by a PW2-level password.

Figure 1. Structure of the memory map in the DS1863.

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Register Reference

The following tables provide an easy reference to the Lower Memory and Tables 01h and 02h. For a description of
the functionality for each bit, please refer to the corresponding register in the DS1863 data sheet. Tables 03h, 04h, and
05h are lookup tables that do not require a separate reference and, therefore, are not included here.

Note: RSVD is an acronym for RESERVED.