Part Number: SN6505BDBVR

Manufacturer: Texas Instruments


Shipped from: Shenzhen/HK Warehouse

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SN6505BDBVR Description

The SN6505x is an isolated, small-form-factor power supply optimized for its ability to drive push-pull transformers with minimal noise and electromagnetic interference. It powers center-tapped, low-profile transformers from a 2.25 V to a 5 V DC source. Slew rate adjustment of the output switch voltage and Spread Spectrum Clocking help reduce noise and EMI to extremely low levels (SSC).

The SN6505x uses complementary output signals from an oscillator and a gate drives circuit to power N-channel power switches referenced to the ground. Two 1-ampere Power-MOSFET switches are included to guarantee a successful device start-up, even when operating under high loads. An external source for the switching clock is available for the precise positioning of switcher harmonics or when using numerous transformer drivers.

Current limiting at 1.7 A, under-voltage lockout, thermal shutdown, and break-before-make circuitry are only some of the inbuilt protection measures. Soft-start functionality built into the SN6505x mitigates the dangers of large load capacitors causing excessive inrush current at power on. Internal oscillators are available in both the SN6505A (with a frequency of 160 kHz) and SN6505B (with a frequency of 420 kHz), with the former being better suited to applications that need to reduce emissions while the latter favors those that demand greater efficiency and a more compact transformer. Small 6-pin SOT23/DBV packages are available for the SN6505x. A temperature range of -55 degrees Celsius to 125 degrees Celsius is used to characterize the device’s performance.

SN6505BDBVR Features

  • For use with transformers, a push-pull driver is required.
  • The input voltage is flexible, operating between 2.25 V and 5.5 V.
  • A high current driver, requiring only a 5 V supply to provide 1 A output.
  • Assume a maximum RON of 0.25 at 4.5 V.
  • Zero or nearly zero EMI interference.
  • Methods of clocking using a spread spectrum.
  • Both a 160 kHz (SN6505A) and a 420 kHz (SN6505B) precision internal oscillator is available (SN6505B).
  • Several gadgets could be synchronized using an external clock source.
  • Handling of slew rates.
  • An upper bound on the current flow rate, or 1.7 A.
  • Only 1 A of electricity is drawn when the device is turned off.
  • There was a thermal shutdown.
  • Around a hundred and twenty-five-degree temperature range from -55 degrees to -55 degrees.
  • SOT23 (DBV) package, a 6-pin small outline terminal strip.
  • Inrush current is mitigated by a soft start.


  • Medical instruments
  • Precision instruments
  • Low-noise filament supplies

Detailed Description

To facilitate low-cost, small-form-factor, isolated DC/DC converters with push-pull topology, the SN6505 incorporates a transformer driver. An oscillator is built into the device and is used to power the gate-drive circuit. To alternately switch the two output transistors on and off, the gate drive, comprised of a frequency divider and a break-before-make (BBM) logic, generates two complementary output signals. By a factor of 2, the oscillator’s output frequency is reduced.

The high pulses of the two signals are separated by a period of silence generated by break-before-make logic. Both signals are low, and the transistors have a large resistance thanks to the BBM logic that must elapse before either gate can assume logic high. This little interval is necessary to prevent a primary from being short on both ends. The generated signals serve as gate-drive inputs for the output transistors.

Device Functional Modes

Device operation can be thought of as having three distinct phases: power-on, normal operation, and shutdown.

● Start-Up Mode

The internal oscillator begins running when the supply voltage at VCC reaches 2.25 V. The switching in the output stage begins, but the drain signals at D1 and D2 have not yet reached their maximum amplitude.

● Soft-Start

The soft-start feature is available on SN6505A and SN6505B devices. When the power is first applied, or when the EN pin goes from Low to High, the gate drive of the output power-MOSFET is ramped up from 0 V to VCC. Thanks to soft-start technology, the massive secondary side decoupling capacitors are charged without experiencing an overshoot in voltage.

● Operating Mode

The device’s power supply is within 10% of its nominal value, and the oscillator functions at full capacity. However, the switching frequencies at D1 and D2 can change depending on the supply voltage and the operating temperature.

● Shutdown-Mode

The device can be put into a very low-power mode via a separate enable pin when not in use. When the device’s Enable pin is not driven, it remains in the disabled state thanks to an internal pull-down resistor. All drain outputs (D1 and D2) are tri-stated when deactivated or when VCC is less than 1.7 V.

● Spread Spectrum Clocking

High-current switching power supplies have a major problem with radiated emissions. To combat this, the SN6505 spreads the emitted energy across a wide range of frequencies by modifying its internal clock. Isolated power supply design is made easier by this Spread Spectrum clocking capability, which drastically enhances the emissions performance of the entire power supply block.

● External Clock Mode

For the system to precisely regulate the switching frequency of the SN6505, the CLK pin can be used to synchronize the device with the system clock and, in turn, with other SN6505 devices. The rising edge of the clock signal or CLK drives the gates.

Application Information

The SN6505 is a transformer driver optimized for push-pull topology-isolated DC/DC converters at a cheap cost and small form size. The gadget has an oscillator that controls the power flow to the gate circuit. To alternately switch the two output transistors on and off, the gate drive, comprised of a frequency divider and break-before-make (BBM) logic, generates two complementary output signals.

Power Supply Recommendations

The gadget is intended to work with a nominal input voltage range of 2.5 V5 V. This input source needs to be stabilized to within 10%. Connecting a 0.1 F by-pass capacitor near the device VCC pin and a 10 F capacitor as close to the transformer center-tap pin is recommended if the input supply is more than a few inches away from the device.


In conclusion, the SN6505x is a highly versatile and dependable push-pull transformer driver with many features, including low noise and EMI, synchronization with external clocks, a large input voltage range, and many internal oscillator options. With built-in protection features and a soft-start function, this device is ideal for various equipment, from radios to medical tools, precision instruments, and low-noise filament power sources.

If you want to upgrade your power system with a revolutionary component that guarantees safe and reliable operation, then the SN6505x is perfect. And when it comes to purchasing this exceptional component, ICRFQ is the trusted supplier that provides outstanding customer service and top-quality products. So don’t wait any longer; upgrade your power system today with the SN6505x from ICRFQ and experience the best reliable and high-quality components.

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