STMicroelectronics L6902

The L6902D is a complete and simple step down switching regulator with adjustable current limit.

Based on a voltage mode structure it integrates a current error amplifier to have a constant voltage and constant current control.

By means of an on board current sense resistor and the availability of the current sense pins (both compatible to Vcc and for Cs- compatible with GND too) a current limit programming is very simple and accurate (±5%). Moreover constant current control can be used to charge NiMH and NiCd batteries.

The device can be used as a standard DC/DC converter with adjustable current limit (set by using the external sense resistor).

The internal robust P-channel DMOS transistor with a typical of 250 mΩ assures high efficiency and a minimum dropout even at high output current level. The internal limiting current (latched function) of typical value of 2.5 A protects the device from accidental output short circuit avoiding dangerous loads damage.

If the temperature of the chip goes higher than a fixed internal threshold (150°C with 20°C hysteresis), the power stage is turned off.

Other protections beside thermal shutdown complete the device for a safe and reliable application: overvoltage protection, frequency folback overcurrent protection and protection vs. feedback disconnection.

The internal fixed switching frequency of 250KHz, and the SO-8 package pin allow to built an ultra compact DC/ DC converter with a minimum board space.

Features

• Up to 1 A output current
• Operating input voltage from 8 V to 36 V
• Precise 3.3 V (±2%) reference voltage
• 5 % output current accuracy
• Output voltage adjustable from 1.235 V to 34 V
• 250 kHz internally fixed frequency
• Voltage feedforward
• Zero load current operation
• Adjustable current limit
• Protection against feedback Disconnection
• Thermal shutdown

STEVAL-FTD01KCB - 1.5 kW, 400 Vdc fault tolerant six-phase motor drive

The STEVAL-FTD01KCB evaluation kit is designed to provide a complete and modular fault-tolerant solution for a six-phase AC motor drive. The kit consists of the STEVAL-FTD01ACB Control Board, the STEVAL-FTD01BCB Main Board, and six STEVAL-FTD01CCB leg Power Boards.

The Control Board has been designed as a 164 pins PCI Express® ready PCB, it hosts a STM32G473QB microcontroller (based on the Arm Cortex-M4 MCU, 170 MHz with 128 Kbytes of flash memory, math accelerator, high analog level integration), an STLINK V3 connector to program the MCU and make a serial communication with the PC.

The Main Board represents the core part of the modular approach of this fault tolerant solution, in fact it is composed by six square holes where the Leg Boards could be mechanically fitted, it hosts a 164 pin female PCI Express® connector, six NTC sensing networks for inverter leg thermal protection, six fuses for short circuits protection, and six relays for phase opening, phase current and phase voltage sensing features. Moreover, the Main Board hosts two L6902D013 step-down switching regulators as an auxiliary power supply and the support for rotor position sensors (hall effect, incremental quadrature encoder and resolver).

Each inverter Leg Board features the STGAP2D, a half-bridge gate driver to isolate the gate driving channels from the low voltage control and interface circuitry. The gate driver is characterized by 4 A capability and rail-to-rail outputs, making the device also suitable for high power inverter applications such as motor drivers in industrial applications. Moreover, the Leg Board hosts the trench gate field-stop, 650 V, 20 A, M series low-loss IGBT (STGB20M65DF2).

The overall system is designed to be galvanically isolated between the MCU and power stages.

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Features

• A single solution based on a Control Board, a Main back-bone board and six Leg Power Boards
• Modular fault-tolerant solution for a six-phase AC Motor Drive
• Each Leg Board hosts:
  • Two STGB20M65DF2 trench gate field-stop, 650 V, 20 A, M series low-loss IGBTs D2PAK-2 package
  • One STGAP2D half-bridge gate driver, 4 A capability, and rail-to-rail outputs
  • One NTC thermistor for overheat protection
  • An insulated metal substrate (IMS)
• The Main Board hosts:
  • A 164 position female PCI express connector as interface with the Control Board
  • Six fast-acting fuses for leg short circuit protection
  • Six NTC sensing networks
  • An auxiliary power supply based on two L6902D013 step-down switching regulators
  • The support to six insulated Current sensors (ICS) for phase current reading
  • Support to quadrature incremental encoder, hall-effect rotor position, and resolver sensors
  • Six relays for motor terminal disconnection
  • The support to phase voltage sensing network
• The Control Board hosts:
  • A STM32G473QB microcontroller
  • A STLinkV3 14-pins connector for MCU programming and serial communication
  • A 164 pins PCI-Express PCB connector

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