The MAX5039/MAX5040 provide intelligent control to power systems where two supply voltages need tracking. These cases include PowerPC®, DSP, and ASIC
systems, which require a lower CORE voltage supply and a higher I/O voltage supply.
The MAX5039/MAX5040 control the output voltage of the CORE and I/O supplies during power-up, powerdown, and brownout situations. They ensure that the two power supplies rise or fall at the same rate, limiting the voltage difference between the CORE and I/O supplies. This eliminates stresses on the processor. The MAX5039/MAX5040 shut down both the CORE and I/O supplies if either one is shorted or otherwise fails to come up.
The MAX5040 provides a power-OK (POK) signal that signals the processor if the CORE supply, the I/O supply, and the system bus supply (VCC) are above their respective specified levels. The MAX5039/MAX5040 are targeted for nominal bus VCC voltages from 4V to 5.5V. The MAX5039/MAX5040 work with CORE voltages ranging from 800mV to about 3V (depending on the gate-to-source turn-on threshold of the external Nchannel MOSFET) and I/O voltages ranging from VCORE to 4V. The MAX5039/MAX5040 provide tracking control of the I/O and CORE voltages using a single external N-channel MOSFET connected across them. This MOSFET is not in series with the power paths and does not dissipate any additional power during normal system operation. The external MOSFET is only on for brief periods during power-up/power-down cycling so a low-cost, small-size MOSFET with a rating of 1/4th to 1/8th of the normal supply current is suitable.
The MAX5039/MAX5040 are offered in space-saving 8-pin µMAX® and 10-pin µMAX packages, respectively.
Key Features
Applications/Uses
Provide Tracking of Two External Power Supplies During Power-Up and Power-Down
Compatible with a Wide Range of External Power Supplies Independent of Output Power
Bus Voltage Undervoltage Lockout Enables/Disables CORE and I/O Supplies Together
Detect Short Circuit on VCORE and VI/O, Disable CORE and I/O Supplies in Either Case
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