1 Features
• 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
• Ultra-low EMI
• Spread spectrum clocking
• Precision internal oscillator options: 160 kHz
(SN6505A) and 420 kHz (SN6505B)
• Synchronization of multiple devices with external
clock input
• Slew-rate control
• 1.7 A Current-limit
• Low shutdown current: <1 μA
• Thermal shutdown
• Wide temperature range: –55°C to 125°C
• Small 6-Pin SOT23 (DBV) package
• Soft-start to reduce In-rush current

2 Applications
• Isolated power supply for CAN, RS-485, RS-422,
RS-232, SPI, I2C, low-power LAN
• Low-noise isolated USB supplies
• Process control
• Telecom supplies
• Radio supplies
• Distributed supplies
• Medical instruments
• Precision instruments
• Low-noise filament supplies

3 Description
The SN6505x 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. Ultra-low noise and EMI are
achieved by slew rate control of the output switch
voltage and through Spread Spectrum Clocking
(SSC). The SN6505x consists of an oscillator
followed by a gate drive circuit that provides
the complementary output signals to drive groundreferenced
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.
SN6505x includes a soft-start feature that prevents
high inrush current during power up with large load
capacitors. SN6505A has a 160 kHz internal oscillator
for applications that need to minimize emissions
whereas SN6505B has a 420 kHz internal oscillators
for applications that require higher efficiency and
smaller transformer size. The SN6505x is available
in a small 6-pin SOT23/DBV package. The device
operation is characterized for a temperature range
from –55°C to 125°C.