LTC4296 no-OS driver#

Supported Devices#

LTC4296-1

Overview#

The LTC4296-1 is an IEEE 802.3cg-compliant, five port, single-pair power over Ethernet (SPoE), power sourcing equipment (PSE) controller. SPoE simplifies system design and installation with standardized power and Ethernet data over a single-pair cable. The LTC4296-1 is designed for interoperability with 802.3cg powered devices (PDs) in 24 V or 54 V systems. The LTC4296-1 delivers power using external, low drain-to-source on resistance (RDS(ON)), N-channel metal-oxide semiconductor field-effect transistors (MOS-FETs), which minimize voltage drop and ensure application ruggedness. High-side circuit breakers with foldback, analog current limit (ACL) provide controlled inrush and short-circuit protection. An optional low-side circuit breaker protects the negative output against backfeed faults, and ground faults in nonisolated applications. PD classification via the serial communication classification protocol (SCCP)and maintain full voltage signature (MFVS) ensure full operating voltage is only applied to the cable when a PD is present. The SWx pins disconnect port power snubbers during detection and classification. PD initiated sleep and wake-up are supported. The WAKEUP pin supports wake-up forwarding. Telemetry, status, and software control features are accessed via a serial peripheral interface (SPI) bus interface with packet error code (PEC) protection.

Applications#

  • Operational technology (OT) systems

  • Building and factory automation systems

  • Field instruments and switches

  • Security systems

  • Traffic control systems

LTC4296 Device Configuration#

Driver Initialization#

In order to be able to use the device, you will have to provide the support for the communication protocol (SPI).

The first API to be called is ltc4296_init. Make sure that it returns 0, which means that the driver was initialized correctly. This function will also reset the LTC4296 by performing a soft reset, putting the device in a known state.

LTC4296 Driver Initialization Example#

SPI Communication Example#

struct ltc4296_dev *dev;
int ret;

struct no_os_uart_init_param ltc4296_uart_ip = {
        .device_id = UART_DEVICE_ID,
        .baud_rate = UART_BAUDRATE,
        .size = NO_OS_UART_CS_8,
        .parity = NO_OS_UART_PAR_NO,
        .stop = NO_OS_UART_STOP_1_BIT,
        .platform_ops = UART_OPS,
        .extra = UART_EXTRA,
};

struct no_os_spi_init_param ltc4296_spi_ip = {
        .device_id = SPI_DEVICE_ID,
        .max_speed_hz = SPI_BAUDRATE,
        .bit_order = NO_OS_SPI_BIT_ORDER_MSB_FIRST,
        .mode = NO_OS_SPI_MODE_0,
        .platform_ops = SPI_OPS,
        .chip_select = SPI_CS,
        .extra = SPI_EXTRA,
};

struct ltc4296_init_param ltc4296_ip = {
        .spi_init = &ltc4296_spi_ip,
};

ret = ltc4296_init(&ltc4296_desc, &ltc4296_ip);
if (ret) {
        pr_info("Initialization error!\n");
        return ret;
}

ret = ltc4296_port_prebias(ltc4296_desc, LTC_PORT0, LTC_CFG_APL_MODE);
if (ret) {
        goto err;
}

ret = ltc4296_port_en(ltc4296_desc, LTC_PORT0);
if (ret)
        goto err;