ADG3304_power up sequence

Question I have contacted with the customer and he will do the test with normal 3.3V / 2.8V power supply tomorrow morning to see the result. If there is still some problem, I will visit them to check the detail situation tomorrow. I have told him your suggestion if they must use the power sequence of 2.8V firstly then 3.3V. 1. Connect a diode between VCCA and VCCY. This will make sure the VCCY will be powered when VCCA power-on. Then VCCY is powered, the diode blocks the voltage between VCCY and VCCA. 2. Make sure the EN is disabled before the VCCY is powered. Also we can connect a large resistor between EN and GND as a solution. Also the engineer mentioned the MAX3377E is OK with all the same test condition. I have attached the datasheet for your reference. Answer I have contacted with the customer and he will do the test with normal 3.3V / 2.8V power supply tomorrow morning to see the result. If there is still some problem, I will visit them to check the detail situation tomorrow. I have told him your suggestion if they must use the power sequence of 2.8V firstly then 3.3V. 1. Connect a diode between VCCA and VCCY. This will make sure the VCCY will be powered when VCCA power-on. Then VCCY is powered, the diode blocks the voltage between VCCY and VCCA. 2. Make sure the EN is disabled before the VCCY is powered. Also we can connect a large resistor between EN and GND as a solution. Also the engineer mentioned the MAX3377E is OK with all the same test condition. I have attached the datasheet for your reference.

ADG3304: used as I2C level shifter

Question I want to interface an 5V I2C EEPROM with my 3.3V MCU by ADG3304 Can ADG3304 be suitable for this applicaton, the I2C SDA is input/output signal Answer I'm afraid we don't have a part that would be suitable for 5V/3V translation in I2C applications. The ADG324X family would be OK but for supply voltages in the range of 1.65 to 3.3V. The ADG3304 does not have enough driving strength to drive 4k7 and 10k loads to ensure the correct logic levels for the I2C bus. You can still try it but the pull-up resistors need to be much larger to limit the load current to 20uA as stated in the datasheet. Please note that if there are masters on both sides of the device, the wired-OR feature of the I2C bus may not work properly.

ADG330x: devices is heating up - what is the reason

Question I use the ADG3304 - Pin VCCY, VCCY, GND, and Enable (ON) defined. The parts heats up mementarily I power up the part. Could you please give me the reason - how to prevent this? Answer You need to have a defined level for A or the Y - Inputs otherwise the two internal amplifiers would work against each other. customer measurements - after proposal: a) please set Enable to GND - does the part heat up? NO Heat . b) please set a1, A2, A3 A4 to 0V - does the part heat up? NO Heat c) please set A1, A2, A3, A4 to VccA - does the part heat up? NO Heat .

ADG3304: Is this device compatible with I2C?

Question I am using ADG3304 to buffer between a 3.3V processor and a 1.8V I2C peripheral. It works OK but it does not like the I2C state when momentarily no one is driving the data line. Is it suitable for I2C? Answer The ADG3304 could work for I2C but it will not 100% meet I2C specifications because of its totem pole output stages. In answer to a previous customer , our ADG330x factory applications engineer wrote : “The ADG3308 was designed to drive capacitive loads, so the current driving capability of its output stage is not significant. The output impedance is about 6K and this values can be used to calculate the output voltage for resistive loads. Also, the architecture used by the output stage is totem-pole which is not fully compliant with the I2C standard that requires open drain/collector outputs. In conclusion, the restriction on resistive loads (pull-up or pull-down resistors) is on the minimum value due to the limited current driving capability and not on the maximum load resistance. For a given resistive load by using the 6K value for the ADG3308 output impedance you should be able to calculate the output voltages for each logic level and check if it is within the specifications required by the application.” (NOTE: our ADG Engineer was referring here to ADG3308 but the same applies to the 4 channel version, ADG3304).

ADG3304_protection method

Question I checked the datasheet, this part can work with the same power supply on Vcca and Vccy, but some cautions should be noted: 1. the power supply issue on page 16 of its datasheet. 2. For not high speed applications (this part is designed for 25Mbps min), you'd better add some series resistors to slow down the rise/fall edges of the logic signals to eliminate ripples on the logic waveforms. Answer For normal operation VCCA must be less than or equal to VCCY as stated in the datasheet. If this condition is not met, say VCCY>VCCA, the supply current drawn by the VCCA pin may increase significantly and damage the ADG3304. To avoid this situation when the IC card is not present, I would recommend to use a diode between VCCA and VCCY (anode to VCCA and cathode to VCCY). This ensures that VCCY does not go below VCCA when the card is removed. Also, the customer may consider to implement a circuitry that grounds the EN pin when the card is not present. This will disable the ADG3304 and reduce the power consumption to a minimum.

ADG330x unused inputs

Question What should I do with unused inputs and outputs on ADG3304? The datasheets mentions connecting the unused inputs to Vcc or to ground. Can you confirm whether we need them or not? Answer The ADG3304 datasheet (page 16) recommends that the inputs of the unused channels (A or Y) should be tied to their corresponding VCC rail (VCCA or VCCY) or to GND. Due to the architecture of this device, it is not necessary to tie both input/outputs, the input side is sufficient You can see this implemented in the circuit schematic from UG-225 for one of our evaluation boards where only the Y7 and Y8 side of the unused channels on ADG3308 is tied to GND.