Automotive, low-noise, 1-A, 420-kHz transformer driver with soft start for isolated power supplies


Product details


Rating Automotive Output current (A) 1 Vin (Min) (V) 2.25 Vin (Max) (V) 5.5 Features Enable, Short-circuit protection, Spread spectrum clocking, Thermal shutdown, Slew-rate control Soft start Yes Operating temperature range (C) -40 to 125 Iout (Max) (A) 1.5 Switching frequency (Min) (kHz) 363 Switching frequency (Max) (kHz) 517 Vout (Max) (V) 16 Switch current limit (Typ) (A) 2 Vout (Min) (V) 0 open-in-new Find other Transformer drivers

Package | Pins | Size

SOT-23 (DBV) 6 5 mm² 2.9 x 1.6 open-in-new Find other Transformer drivers


  • AEC-Q100 (Grade 1) qualified for automotive applications
    • Device temperature grade 1: –40°C to +125°C, TA
  • Functional Safety-Capable
  • Push-pull driver for transformers
  • Wide input voltage range: 2.25 V to 5.5 V
  • High output drive: 1 A at 5 V supply
  • Low RON 0.25 Ω max at 4.5 V supply
  • Reduced conducted and radiated EMI
  • Spread spectrum clocking
  • Precision internal oscillator options: 160 kHz (SN6505A-Q1) and 420 kHz (SN6505B-Q1 and SN6505D-Q1)
  • Synchronization of multiple devices with external clock input
  • Slew-rate control
  • 1.7 A Current-limit
  • Low shutdown current: <1 µA
  • Thermal shutdown
  • Small 6-Pin SOT23 (DBV) package
  • Soft-start enabled (SN6505A-Q1 and SN6505B-Q1) to reduce in-rush current and soft-start disabled (SN6505D-Q1) for fast start-up
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The SN6505x-Q1 is a low-noise, low-EMI push-pull transformer driver, specifically designed for small form factor, isolated power supplies. It drives low-profile, center-tapped transformers from a 2.25 V to 5 V DC power supply. Very low noise and EMI are achieved by slew rate control of the output switch voltage and through Spread Spectrum Clocking (SSC). The SN6505x-Q1 consists of an oscillator followed by a gate drive circuit that provides the complementary output signals to drive ground-referenced N-channel power switches. The device includes two 1-A Power-MOSFET switches to ensure start-up under heavy loads. The switching clock can also be provided externally for accurate placement of switcher harmonics, or when operating with multiple transformer drivers. The internal protection features include a 1.7 A current limiting, under-voltage lockout, thermal shutdown, and break-before-make circuitry. SN6505A-Q1 and SN6505B-Q1 include a soft-start feature that prevents high inrush current during power up with large load capacitors. Soft-start feature has been disabled in SN6505D-Q1 for applications that require fast output start-up.SN6505A-Q1 has a 160 kHz internal oscillator for applications that need to minimize emissions whereas SN6505B-Q1 and SN6505D-Q1havea 420 kHz internal oscillators for applications that require higher efficiency and smaller transformer size. The SN6505x-Q1 is available in a small 6-pin SOT23/DBV package. The device operation is characterized for a temperature range from -40°C to 125°C.

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Technical documentation

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Type Title Date
* Data sheet SN6505x-Q1 Low-Noise 1-A Transformer Drivers for Isolated Power Supplies datasheet (Rev. D) Oct. 26, 2020
Application note How to Reduce Emissions in Push-Pull Isolated Power Supplies Sep. 07, 2021
Functional safety information SN6505x-Q1 Functional Safety, FIT Rate, Failure Mode Distribution and Pin FMA Jun. 18, 2020
Technical article Streamlining isolated CAN and power interface designs for 48-V HEV systems May 01, 2020
Technical article Why signal isolation matters in 48-V HEV/EV systems Nov. 20, 2019
Third party documents Simplify Isolated CAN, Power Interfaces for HEV 48-V Systems Jul. 16, 2019

Design & development

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Hardware development

document-generic User guide

The evaluation module (EVM), featuring a SN6505B transformer driver, also contains a small form-factor transformer, simple rectifier circuit, and voltage regulator that can be used to simulate a complete isolated power-supply system suitable for many applications.

  • Low-noise 1-A transformer driver for isolated power supplies, 420-kHz internal clock
  • 5-V input, 5-V output isolated power
  • Simple rectifier circuit along with low droput (LDO) regulator gives rectified voltage of 5 V
  • Provision for feeding external clock to the device
  • EVM tested for device functionality (...)

Software development

SLLC470.ZIP (205486 KB)

Design tools & simulation

SLLM292.ZIP (11 KB) - IBIS Model
SLLM301B.ZIP (4 KB) - PSpice Model
SLLM322.TSC (2495 KB) - TINA-TI Reference Design
SLLM323.TSC (2466 KB) - TINA-TI Reference Design
SLLM324.ZIP (40 KB) - TINA-TI Spice Model
PSpice® for TI design and simulation tool
PSPICE-FOR-TI — PSpice® for TI is a design and simulation environment that helps evaluate functionality of analog circuits. This full-featured, design and simulation suite uses an analog analysis engine from Cadence®. Available at no cost, PSpice for TI includes one of the largest model libraries in the (...)
  • Leverages Cadence PSpice Technology
  • Preinstalled library with a suite of digital models to enable worst-case timing analysis
  • Dynamic updates ensure you have access to most current device models
  • Optimized for simulation speed without loss of accuracy
  • Supports simultaneous analysis of multiple products
  • (...)
SPICE-based analog simulation program
TINA-TI TINA-TI provides all the conventional DC, transient and frequency domain analysis of SPICE and much more. TINA has extensive post-processing capability that allows you to format results the way you want them. Virtual instruments allow you to select input waveforms and probe circuit nodes voltages (...)
document-generic User guide

Reference designs

HEV/EV traction inverter power stage with 3 types of IGBT/SiC bias-supply solutions reference design
TIDA-020014 — This reference design presents a traction inverter single-phase power stage with three 12-V car battery inputs, 4.2-W bias supply solutions for hybrid electric vehicle and electric vehicle (HEV/EV) systems. All bias-supply solutions accept a wide input range of 4.5 V to 42 V DC from a 12-V car (...)
document-generic Schematic

CAD/CAE symbols

Package Pins Download
SOT-23 (DBV) 6 View options

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