I2C DIP switches (multiplexed/latched EEPROMs)

I2C commands and/or hardware pins are used to select between the default values or the setting programmed from the I2C bus and stored in the onboard I2C EEPROM register. These onboard values can be changed at any time via the I2C bus. The non-volatile I2C EEPROM register values stay resident even when the device is powered down. The device powers up with either the hardware pin inputs or the EEPROM retained value on the hardware output pins depending on the position (H or L) of the mux select pins. The EEPROMs have 10-year memory retention and are rated for 3000 write cycles in the data sheet but have been tested to 50,000 cycles with no failures.

The Multiplexed/Latched EEPROMs were designed for use with Intel^® processors to implement the Speed Step™ technology for notebook computers (selects different processor voltages when connected to AC power, the battery, or in a deep sleep/deeper sleep mode) or Dual BIOS selection (select different operating systems during start-up).

Multiplexed/Latched EEPROMs can be used for CPU Voltage IDentification code (VID) configuration. In the VID configuration application, they typically reside between the CPU and Voltage Regulator Module (VRM). They are used to bypass the CPU-defined VID values and provide a different set of VID values to the VRM, if an increase in the CPU voltage is desired. An increase in CPU voltage combined with an increase in CPU frequency leads to a performance boost of up to 7.5%. Lower CPU voltage reduces power consumption.

Designers have, however, found other uses for these devices. They are used in VGA/tuner cards (to select the appropriate transmission standard) and as replacements for DIP switches or jumpers, since the settings can be easily changed via I2C/SMBus without having to power down the equipment to open the cabinet. The non-volatile memory retains the most current setting selected before the power is turned off.

The PCA8550 is a 16-pin CMOS device with a single 4-bit 2-to-1 multiplexer and 1-bit latch and consists of one 5-bit non-volatile EEPROM register, 4 hardware pin inputs, and a 4-bit multiplexed output with one latched EEPROM bit.

The PCA9558 is a highly integrated 28-pin CMOS device composed of a single 5-bit 2-to-1 multiplexer and 1-bit latch (one 6-bit non-volatile EEPROM register, 5 hardware pin inputs, and a 5-bit multiplexed output with one latched EEPROM bit) with an 8-bit I/O expander and a 2K serial EEPROM with write protect.

• The multiplexer can be used to select digital information between a set of 5-bits of default hardware inputs and an alternative set of inputs provided by the I2C/SMBus interface and stored in the EEPROM.
• The I/O expander function is used to control, monitor, or collect remote information or power LEDs. Monitored or collected information can be read through the I2C/SMBus or can be stored in the internal 2K serial EEPROM.
• Information such as card identification or revision/maintenance history can be stored in the EEPROM on every card and can be read or written via the I2C/SMBus when required.

The PCA9559 is a 20-pin CMOS device with a single 5-bit 2-to-1 multiplexer and 1-bit latch and consists of one 6-bit non-volatile EEPROM register, 5 hardware pin inputs, and a 5-bit multiplexed output with one latched EEPROM bit.

The PCA9560 is a 20-pin CMOS device with a dual 5-bit 3-to-1 multiplexer and 1-bit latch and consists of two 6-bit non-volatile EEPROM registers, 5 hardware pin inputs, and a 5-bit multiplexed output with one latched EEPROM bit. The PCA9560 is footprint identical to the PCA9559 but has two internal EEPROM registers to allow for three preprogrammed setting (e.g., AC power/battery power, deep sleep, or deeper sleep mode) instead of only two (performance operation and deep sleep mode). The PCA9560 is a drop-in replacement for the PCA9559 without any software modifications required if only one of the non-volatile EEPROMs is going to be used.

The PCA9561 is a 20-pin CMOS device with a quad 6-bit 5-to-1 multiplexer and consists of four 6-bit non-volatile EEPROM registers, 6 hardware pin inputs, and a 6-bit multiplexed output. The PCA9561 is unique in that it has 6 hardware input pins and four internal 6-bit EEPROM registers. Output selection is possible between any one of these five 6-bit values at any time via the I2C bus. The PCA9561 offers the possibility to extend to 5 different settings (4 stored internally and 1 external) and allows a more accurate CPU voltage tuning depending on specific applications.

The main advantage of the PCA9558/59/60/61 over the PCA8550 is that they're open-drain buffers, which allows them to work with all generations of processors instead of only 2.5V processors.

• Operating voltage of 3.0V to 3.6V
• 5.0V tolerant open drain outputs
• 5.0V and 2.5V tolerant inputs
• Operating temperature of 0°C to 70°C
• Operating frequency up to 400kHz
• Internal non-volatile EEPROM registers with a minimum of 3000 write cycles and a minimum of 10 year memory cell data retention
• Internal non-volatile registers programmable and readable via I2C/SMBus
• Input hardware pins readable via I2C/SMBus
• Selection between input hardware pins and non-volatile EEPROM registers
• Write protect feature controls the ability to write to the non volatile EEPROM registers
• 2 address pins, allowing up to 4 devices on the I2C/SMBus
• ESD protection exceeds 2000V HBM per JESD22-A114, 200V MM per JESD22-A115, and 1000V CDM per JESD22-C101
• JEDEC Standard JESD78 Latch-up testing exceeds 100mA
• Offered in SO (D) and TSSOP (PW) packages
• Manufactured in high-volume CMOS process

PCA8550	16	1	5	4	4	Yes
PCA9558	28	1	6	5	5	Yes
PCA9559	20	1	6	5	5	Yes
PCA9560	20	2	6	5	5	Yes
PCA9561	20	4	6	6	6	No

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	PCA8550		4-Bit Multiplexed/1-Bit Latched 5-Bit I2C EEPROM
	PCA9559		5-Bit Multiplexed/1-Bit Latched 6-Bit I2C EEPROM
	PCA9560		Dual 5-Bit Multiplexed 1-Bit Latched I2C EEPROM
	PCA9561		Quad 6-Bit Multiplexed I2C EEPROM
	Datasheet (May 17, 2004) PCA9561D SO-20 Production SOT163-1 Pb-Free MSL=1 PCA9561PW TSSOP-20 Production SOT360-1 Pb-Free MSL=1 Family Functions Literature Models Support Docs Price Buy Online More...

• PCA8550 Device Highlight

	PCA9558		5-Bit Multiplexed/1-Bit Latched 6-Bit I2C EEPROM and Octal SMBus Registered Interface with 256-Byte I2C EEPROM