MAXIM MAX7301AAX+T

The MAX7301 compact, serial-interfaced I/O expander (or general-purpose I/O (GPIO) peripheral) provides microprocessors with up to 28 ports. Each port is individually user configurable to either a logic input or logic output. Each port can be configured either as a push-pull logic output capable of sinking 10mA and sourcing 4.5mA, or a Schmitt logic input with optional internal pullup. Seven ports feature configurable transition detection logic, which generates an interrupt upon change of port logic level. The MAX7301 is controlled through an SPI-compatible 4-wire serial interface. The MAX7301AAX and MAX7301ATL have 28 ports and are available in 36-pin SSOP and 40-pin TQFN packages, respectively. The MAX7301AAI has 20 ports and is available in a 28-pin SSOP package.

The MAX7301 GPIO peripheral provides up to 28 I/O ports, P4 to P31, controlled through an SPI-compatible serial interface. The ports can be configured to any combination of logic inputs and logic outputs, and default to logic inputs on power-up. Any I/O port can be configured as a push-pull output (sinking 10mA, sourcing 4.5mA), or a Schmitt-trigger logic input. Each input has an individually selectable internal pullup resistor. Additionally, transition detection allows seven ports (P24 through P30) to be monitored in any maskable combination for changes in their logic status. A detected transition is flagged through an interrupt pin (port P31). The port configuration registers set the 28 ports, P4 to P31, individually as GPIO. A pair of bits in registers 0x09 through 0x0F sets each port’s configuration. The 36-pin MAX7301AAX and 40-pin MAX7301ATL have 28 ports, P4 to P31. The 28-pin MAX7301AAI is offered in 20 ports, P12 to P31. The eight unused ports should be configured as outputs on power-up by writing 0x55 to registers 0x09 and 0x0A. If this is not done, the eight unused ports remain as floating inputs and quiescent supply current rises, although there is no damage to the part.

The MAX7301 offers 20 or 28 I/O ports, depending on package choice. Two addressing methods are available. Any single port (bit) can be written (set/cleared) at once; or, any sequence of eight ports can be written (set/cleared) in any combination at once. There are no boundaries; it is equally acceptable to write P0 through P7, P1 through P8, or P31 through P38 (P32 through P38 are nonexistent, so the instructions to these bits are ignored).

• Industry-Standard 4-Wire Interface Simplifies Expansion of I/O Ports to Up to 28 I/Os Independent of Microprocessor Architecture
• High-Speed, 26MHz, SPI-/QSPI-/MICROWIRE- Compatible Serial Interface
• 2.25V to 5.5V Operation
• 20 or 28 I/O Ports Configurable as Push-Pull Logic Output, Schmitt Logic Input or Schmitt Logic Input with Internal Pullup
• Logic Transition Detection for Seven I/O Ports
• Low Power Consumption Reduces Power-Supply Requirements
• 11μA (max) Shutdown Current

• White Goods
• Gaming Machines
• Industrial Controllers
• System Monitoring