General description
The TEA1721 is a small and low cost module Switched Mode Power Supply (SMPS)
controller IC for low power applications (up to 5 W) and operates directly from the rectified
universal mains input. The device includes a high voltage power switch (700 V) and has
been optimized for flyback converter topologies to provide high-efficiency over the entire
load range with ultra-low power consumption in the no-load condition. It provides a circuit
for start-up directly from the rectified mains voltage without any external bleeder circuits.
The converter operates as a regulated voltage source from no-load up to the maximum
output current and operates as current source that delivers the maximum current over a
broad output voltage range. Using the TEA1721, a low power converter can be built at
minimum cost and with the minimum number of external components.
The controller regulates the output voltage with primary-side sensing which eliminates the
need for an additional secondary feedback circuitry and simplifies the design. At higher
power levels, a frequency and current control mode is used. It operates with Burst mode
control at low power levels and no-load condition. The burst mode minimizes audible
noise and provides an energy saver state which reduces the power consumption in
no-load condition. The Burst mode frequency of 430 Hz enables no-load power
consumption below < 10 mW at high mains input.

Features and benefits
Power features:
 Low power SMPS controller with integrated power switch designed for applications up
to 5 W
 700 V high voltage power switch for global mains operation
 Primary sensing for control of the output voltage without optocoupler and secondary
feedback circuitry
 Minimizes audible noise in all operation modes
 USB battery charging and Energy Star 2.0 compliant
 Jitter function for reduced EMI
Green features:
 Enables no-load power consumption below < 10 mW
 Very low supply current in no-load condition with energy saver mode
 Incorporates a high voltage start-up circuit with zero current consumption under
normal switching operation
 Available in halogen-free and Restriction of Hazardous Substances (RoHS) SO7
package
Protective functions:
 OverVoltage Protection (OVP) on Feedback control (FB) pin with auto-restart
 UnderVoltage LockOut (UVLO) protection on IC supply pin
 OverTemperature Protection (OTP)
 Soft-start by reduced peak current for zero and low output voltage
 Demagnetization protection for guaranteed discontinuous conduction mode operation
 Open and short-circuit protection of the Feedback control (FB) pin
 Short-circuit protection of the charger output