AFE4490: TX REF Voltage

Chloe Melnick

Part Number: AFE4490

I am trying to change the value of the TX_REF pin to output 1V as is suggested by the manual. I am writing to the CONTROL 2 register and placing a 10 in bits 18 and 17 however my output voltage on TX REF is still 5V, not 1V.

I am not sure what I am doing wrong.

Code is below:

GPIO_setOutputHighOnPin(GPIO_PORT_P6, GPIO_PIN0);

uint8_t i;
uint8_t wreg2[4]={0x23,0x04,0x00,0x00};
GPIO_setOutputLowOnPin(GPIO_PORT_P1, GPIO_PIN4);
for (i=0; i<4; i++)
{
while(!USCI_A_SPI_getInterruptStatus(USCI_A1_BASE,USCI_A_SPI_TRANSMIT_INTERRUPT));
USCI_A_SPI_transmitData(USCI_A1_BASE, wreg2[i]);
}

GPIO_setOutputHighOnPin(GPIO_PORT_P1, GPIO_PIN4);
}

over 5 years ago

0 Praveen Aroul over 5 years ago

TI__Mastermind 49986 points

Hello Chloe,

It seems like the device may be in power-down mode. Did you check the status of the AFE_PDNZ pin? It should be driven to a logic high if you have connected to MCU IO port.

After ensuring the AFE power supplies are fine and setting RESETZ and AFE_PDNZ to logic high, you should measure the following:

a) 0.75V on TX_REF pin (pin#9)

b) 1V on BG pin (pin#7)

c) 0.9V on VCM pin (pin#4)

Now after programming the register 23h to 0400h, you should measure 1V at the TX_REF pin.

0 Chloe Melnick over 5 years ago in reply to Praveen Aroul

Prodigy 210 points

Hi Praveen,

I don't have the power-down pin connected to my MCU but it is high. It is reading 2.0 V right now.

0 Praveen Aroul over 5 years ago in reply to Chloe Melnick

TI__Mastermind 49986 points

Chloe,

What are your supply voltages? Is the AFE_PDNZ pin tied to any supply voltage or is it just floating?

If it is floating, then you will need to connect to the RX_DIG_SUP.

Have you also checked the sequence that I mentioned in my previous post?

0 Chloe Melnick over 5 years ago in reply to Praveen Aroul

Prodigy 210 points

TX supply is 5V and RX_DIG_SUP is 3.3V.

AFE_PDNZ is just floating.

a) 5 V on TX_REF pin (pin#9)

b) 0 V on BG pin (pin#7)

c) 0 V on VCM pin (pin#4)

0 Praveen Aroul over 5 years ago in reply to Chloe Melnick

TI__Mastermind 49986 points

You will need to connect AFE_PDNZ to the RX_DIG_SUP.

0 Chloe Melnick over 5 years ago in reply to Praveen Aroul

Prodigy 210 points

Thanks. I will try that. Alternatively I can connect it to a port pin on my microcontroller, correct?

0 Chloe Melnick over 5 years ago in reply to Chloe Melnick

Prodigy 210 points

I also have a limited number of available MCU ports. I saw on an earlier post https://e2e.ti.com/support/data-converters/f/73/t/392555?tisearch=e2e-sitesearch&keymatch=afe4490%252520DIAG_END you talk about what to do with some of the I/Os if you don't have enough MCU ports. Can you verify what can be done with each pin if I don't have enough ports to connect to on my MCU. The post didn't clarify everything for me. What should I do with the remaining pins?

Pin 20, AFE_PDNZ: Connect to MCU or RX_DIG_SUP

Pin 21, DIAG_END:

Pin 22, LED_ALM:

Pin 23, PD_ALM:

SPI CHANNELS: all connected

Pin 28, ADC_RDY: I have this connected to MCU

Pin 29, RESETZ: I have this connected to MCU.

Pin 30, CLK_OUT:

Thanks,

Chloe

0 Praveen Aroul over 5 years ago in reply to Chloe Melnick

TI__Mastermind 49986 points

Duplicate post:

Refer here for response: https://e2e.ti.com/support/data-converters/f/73/p/878339/3249319#3249319

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AFE4490: TX REF Voltage