Robust High Voltage I/O and Hot Swap Controller 3-WIRE POINT-TO-POINT INTERFACE WIRE 24V VDD VL 3.3V LTC2874 HOT SWAP ±50V SPI PORT DESCRIPTION OUTPUT VOLTAGE ABS MAX VOLTAGE CURRENT ESD ±8kV L+ POWER 8V TO 34V +50V RSENSE CONFIGURABLE CQ DATA 8V TO 34V ±50V 100mA (PARALLELABLE) ±8kV GND GROUND – – – – IRQ TXD1 L+1 TXEN1 CQ1 RXD1 GND µC ILLM TXD4 L+4 TXEN4 CQ4 PORT4 RXD4 One IC, 4 Ports, Many Applications The LTC®2874 is a rugged, 4-port interface for powering and controlling all types of remote devices. Output supply voltage and inrush current are ramped up in a controlled manner using external N-channel pass transistors, providing improved robustness compared to fully integrated solutions. The LTC2874 features line noise suppression, connection sensing, automatic restart and many register-programmable parameters. Configuration and fault reporting are exchanged using a 4-wire SPI interface that operates at clock rates up to 20MHz. Features n n n n n n n n n n n n n Four Bidirectional I/O Ports ±50V Protection Up to 250kHz Operation at 12V or 24V I/O Hot Swap™ Protected Supply Outputs with Discrete Power MOSFETs for Ruggedness and Flexibility Rugged CQ Line Drivers with Adjustable Slew Rate and 100mA (4-Port), 200mA (2-Port) or 400mA (1-Port) Drive Capability Automatic Cable Sensing Programmable L+ Current Limit with Foldback Programmable Current Sink, Start-Up Current Pulse and Noise Suppression Short-Circuit, Input UVLO/UV/OV and Thermal Protection Optional Interrupt and Auto-Retry After Faults 2.9V to 5.5V Logic Supply for Flexible Digital Interface 4-Wire 20MHz SPI-Compatible Serial Interface Small 38-Pin 5mm × 7mm QFN and TSSOP Packages Hot Swap Controlled Power L+1 L+2 FLDBK_MODE = 1 L+3 10V/DIV L+4 FLDBK_MODE = 0 4ms/DIV Data Signaling CQ1 CQ2 20V/DIV CQ3 CQ4 4µs/DIV LOAD : 4nF CQ1, CQ3: COM3 = 0 CQ2, CQ4: COM3 = 1 L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and Hot Swap is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. Applications 8V to 34V 1µF 100µF VDD VL 2.9V to 5.5V 1µF 0.2 CS SCK SDI SDO IRQ µC LTC2874 SENSE-1 SENSE-2 SENSE-3 SENSE-4 TXEN1 GATE1 TXD1 GATE2 10Ω GATE3 RXD1 GATE4 TXEN2 MICROPROCESSOR, DIRECT CONTROL, OR FIXED (SPI ONLY) SENSE+ L+1 O1 TXD2 CQ1 I/O-2 RXD2 L+2 O3 TXEN3 CQ2 I/O-4 TXD3 L+3 O5 CQ3 I/O-6 L+4 O7 CQ4 I/O-8 RXD3 TXEN4 TXD4 RXD4 GND Choose Your I/O The LTC2874 connects directly to a wide array of standard inputs and outputs. From transistors and relays to resistive, capacitive and inductive loads, the LTC2874 provides microprocessors with direct and/or SPI control over many types of components typically found in such systems as aviation units, industrial equipment, traffic controls and lighting networks, to name a few. Thanks to high voltage outputs with high drive strength, the LTC2874 can even drive challenging loads such as incandescent lamps, without damage from overheating. 10µF 5V 53.6k 24V 100µF 1µF 1µF µC LDOIN LDO FBLDO FBOUT VL 3.3V BD CS SCK SDI SDO VDD SENSE+ 56µH 1/2 LTC2874 SENSE-1 SENSE-2 IRQ GATE1 10.2k 19.6k 10Ω LT3669 RT BST RST 220nF SW DIO EN/UVLO L+ GATE2 L+1 TXEN1 TXD1 RXD1 TXEN2 TXD2 RXD2 SYNC CPOR WAKE SR ILIM SC1 TXEN1 CQ1 TXD1 CQ1 RXD1 L+2 TXEN2 CQ2 Q2 TXD2 4.7µF GND GND SC2 Remote Communications The LTC2874 provides a robust interface between low voltage components, such as microprocessors, and noisy high voltage environments cables must often snake through. Matching the LTC2874’s ruggedness, the optional LT®3669 transceiver with integrated step-down regulator and LDO can be used to interface with devices, such as encoders or piezo sensors/actuators. Together, the LTC2874 and LT3669 provide a complete high SNR large signal swing communications solution, transmitting both power and data for self-powered applications. www.linear.com/2874B n 1-800-4-LINEAR 0215