The MAX77812 is a quad-phase, high-current, step-down (buck) converter for high-end gaming consoles, VR/AR headsets, DSLR cameras, drones, network switches and routers, and FPGA systems that use multicore processors. This document introduces the factory-programmable OTP (one-time programmable) options that the MAX77812 provides.
The MAX77812’s flexible architecture enables users to have full control of the multiphase buck converter operation through the I2C/SPI interface, such as control of output voltages, startup and shutdown sequences, ramp-up/down slew rates. (For details, see the PMIC Registers section of the data sheet.)
Factory Default Settings
When valid input supply voltages are applied to the SYS, VIO, and CE pins, a host processor in the system can read and write the functional registers of the MAX77812 and it can override the factory default setting values, even before the converter output is enabled. This feature allows the MAX77812 to support many applications that require different operating conditions.
However, in case the MAX77812 is the main supply to the host processor in the system and the host processor requires unique supply voltages and a power-up sequence, a new factory default option may be needed. In order to address this, the MAX77812 offers multiple factory default settings. (See the Ordering Information section in the MAX77812 data sheet). If your applications require a specific combination of default output voltages and startup sequence that is not available in the ordering information, contact your Maxim’s sales representative.
Table 1 shows the factory-programmable operating parameters.
|Default Output Voltage|
|0x23||M1_VOUT[7:0]||Master 1 Output Voltage|
|0x24||M2_VOUT[7:0]||Master 2 Output Voltage|
|0x25||M3_VOUT[7:0]||Master 3 Output Voltage|
|0x26||M4_VOUT[7:0]||Master 4 Output Voltage|
|Default Startup Delay|
|0x07||DLY_STEP||Delay Time Step Selection|
|0x07||M2_STUP_DLY[4:0]||Master 2 Startup Delay Time|
|0x08||M3_STUP_DLY[4:0]||Master 3 Startup Delay Time|
|0x09||M4_STUP_DLY[4:0]||Master 4 Startup Delay Time|
Default Output Voltage
The output voltage of the MAX77812 is programmable from 0.25V to 1.525V in 5mV steps. Mx_VOUT[7:0] is the output voltage control register for normal operation, and its default value is OTP-programmable.
Default Startup Delay
The startup delay times between the master phases are programmable from 0ms to 62ms with a step size of 1ms or 2ms. They are determined by STUP_DLYx registers, and the default startup delay can be programmed at the factory.