The MC121-Q1 integrates a test and programming mode where the PWM/DC and
FG/RD pins support an I2C interface for device configuration and testing.
The I2C interface also gives access to the one-time programmable (OTP)
memory. Programming the registers selects the device configurations described in the
previous sections. Figure 6-31 shows the basic hardware configuration for configuring and programming the MC121-Q1.
The MC121-Q1 enters test mode and OTP mode with the following procedure.
- Pull the FG/RD pin low and apply a high frequency signal in the range of
(416-833) kHz at any duty between (20-80)% for 15 to 20 cycles to the PWM/DC pin
to enter the test mode. The I2C interface is active in test
mode.
- Communicate with MC121-Q1 over I2C to read and write to
the registers in Section 7 to configure the registers.
- To maintain reliable OTP
memory programming through I2C communication, maintain the MC121-Q1 power supply pin voltage (VM) above
8V throughout the entire duration of the communication.
- Write the OTP mode entry key
02h, 01h, 04h to the USR_OTP_PRG_UNLOCK register in successive
write-frames to unlock OTP mode.
- To burn the OTP memory, write
1b to the USR_OTP_PROG_ALL bit in USR_OTP_CFG Register.