Datasheet

MSL2021 [DATASHEET]

42062A–LED–02/2013

13.11 Registers 0x60 and 0x61, EEPROM Access

These registers control access to the EEPROM. See “EEPROM and Power-Up Defaults” and “EEPROM Address and

Control/Status Registers” on page 26 for information.

13.12 Password registers (PW(HIGH) and PW(LOW), 0x68 and 0x69)

Use these registers to enter the password when locking the look-up table of the MSL2021. See section “MSL2021 Look-

Up Table Lockout Procedure” on page 23 for details about locking the look-up table.

Table 13-11. Password registers

(PW(HIGH) and PW(LOW), 0x68 and 0x69), defaults highlighted

14. I²C Serial Interface

The MSL2021 operates as a slave that sends and receives data through an I²C/SMBus compatible 2-wire serial

interface. The interface is not needed for operation, but is provided to allow control and monitoring of device functions.

These functions include changing the Look-Up Table and equation parameters, changing the string current reference

feedback voltages, reading and adjusting the fault response behavior and status, putting the device to sleep without

losing the register settings, and programming the EEPROM. The I²C/SMBus compatible interface is suitable for 100kHz,

400kHz and 1MHz communication. The interface uses data I/O SDA and clock input SCL to achieve bidirectional

communication between master and slaves. Fault output FLTB optionally alerts the host system to faults detected by the

MSL2021 (Figure 14-1 on page 32 and “Fault Conditions” on page 15). During over temperature shutdown (TSD) the

serial interface remains active.

The master, typically a microcontroller, initiates all data transfers, and generates the clock that synchronizes the

transfers. SDA operates as both an input and an open-drain output. SCL operates only as an input, and does not perform

clock-stretching. Pull-up resistors are required on SDA, SCL and FLTB.

••• •••

D Threshold = (5  150mV) + 250mV = 1V 1 1 1 0 0 1 0 1

••• •••

D Threshold = (15  150mV) + 250mV = 2.5V x 1 1 0 1 0 1 1

Address /

Default

D7 D6 D5 D4 D3 D2 D1 D0

PWV(HIGH) 0x68 Password High Byte [15:8]

PWV(LOW) 0x69 Password Low Byte [7:0]

DEFAULT 111111 1 1