This SN6505A and SN6505B evaluation module allows the user to evaluate the performance and features of the SN6505A and SN6505B in an actual isolated power application. This includes the transformer, rectifier, and low- dropout (LDO) voltage regulator.
The complementary output signals (D1 and D2) from the SN6505x are ground- referenced, N- channel, power switches that drive the primary side of the center- tapped transformer. The secondary of the transformer has its center- tap referenced to an isolated ground, and the complementary outputs are rectified through a simple two- diode bridge. The make- before- break feature of the two driver outputs from the SN6505x ensures that only one side of the transformer is driven at a time. After being rectified, the dc voltage is smoothed and routed to the TPS76701QD voltage regulator. The regulator outputs a stable, regulated +5 - Vdc output that is used to drive downstream circuitry.
The EVM is the SN6505x EVM which is configured for +5 - Vdc/ input and +5 - Vdc output.
The SN6505xEVM printed- circuit board (PCB) contains an SN6505x, transformer, and voltage regulator. The board has separate and isolated grounds across the isolation transformer allowing evaluation of the isolated power supply system contained on the EVM. Although the transformer secondary can be wound to provide any isolated voltage, the EVM uses a transformer with a 1:1.1 turns ratio, ideal for generating the rectified voltage required by the TPS76701QD regulator.
The SN6505x is operated using either a single +5 - V (± 10%), or single +5 - V (± 10%) dc power supply. On this EVM, the turn- ratio of the transformer is 1:1:1, providing a slight step- up voltage function. This allows evaluation of the system performance using a supply voltage anywhere within the range of +5 - V dc to 5.5- Vdc. The small amount of dc current required also allows operation of the EVM from a battery. The input dc power supply must be connected to the J1 terminal block on the left side of the EVM. No other controls are required to operate the EVM. The SN6505X oscillates and drives the transformer when dc voltage is applied.
The right side of the isolation transformer contains a two- diode rectifier, filter capacitors, and a voltage regulator. Because the purpose of the EVM is to generate isolated power across the transformer, a separate power supply on the right side of the EVM is unnecessary. The rectified, unregulated output voltage is observed at TP5. Monitor the output from the transformer while varying the input voltage to the SN6505x. The regulated output is available at TP7. Connect external circuitry and/or loading to evaluate the operating range, line regulation, load regulation, and efficiency of the EVM. The ground reference on the right side of the transformer (GND2) is not connected to the ground of the SN6505x (GND1), demonstrating the isolation feature of the EVM.
TI SN6505BEVM