General description

The TEA18361LT is a controller IC for low-cost switched-mode power supplies (SMPS).

It is intended for flyback topologies. The built-in green functions provide high efficiency at

all power levels.

At high power levels, the flyback operates in quasi-resonant (QR) mode. At lower power

levels, the controller switches to frequency reduction (FR) or discontinuous conduction

mode (DCM) and limits the peak current to approximately 25 % of the maximum peak

current. Valley switching is used in all operating modes.

At low power levels, when the flyback switching frequency drops below 25 kHz, the

flyback converter switches to burst mode. A special burst mode has been integrated

which reduces the optocurrent to a minimum level, ensuring high efficiency at low power

and excellent no load power performance. As the switching frequency in this mode has a

minimum value of 25 kHz while the burst frequency is below 800 Hz, the frequencies are

outside the audible range. During the non-switching phase of the burst mode, the internal

IC supply current is minimized for further efficiency optimization.

The TEA18361LT includes an accurate overpower protection (OPP). The OPP enables

the controller to operate in overpower situations for a limited amount of time. If the output

is shorted, the system switches to low-power mode where the output power is limited to a

lower level.

The TEA18361LT is manufactured in a high-voltage silicon-on-insulator (SOI) process.

The SOI process combines the advantages of a low-voltage process (accuracy, highspeed

protection, functions, and control), while maintaining the high-voltage capabilities

(high-voltage start-up, low standby power, and an integrated X-capacitor discharge

function).

The TEA18361LT enables low-cost, highly efficient, and reliable supplies for power

requirements up to 75 W to be designed with a minimum number of external

components.

All values mentioned in this data sheet are typical values, unless otherwise specified.

Features and benefits

2.1 General features

• SMPS controller IC for low-cost applications

• Large supply voltage range (up to 30 V)

• Integrated high-voltage start-up

• Continuous VCC regulation during start-up and protection via the HV pin, allowing a

minimum VCC capacitor value

• Reduced optocurrent in burst mode enabling low no load power consumption

• Operating frequencies in all operating modes are outside the audible area

• Integrated X-capacitor discharge

• Adjustable soft start

• Power-down mode via the PROTECT pin

Green features

• Low supply current during normal operation (0.6 mA without load)

• Low supply current during non-switching state in burst mode (0.2 mA)

• Valley switching for minimum switching losses

• Frequency reduction with fixed minimum peak current to maintain high efficiency at low

output power levels

Protection features

• Mains voltage independent overpower protection (OPP)

• Overtemperature protection (OTP)

• Integrated overpower timeout

• Integrated restart timer for system fault conditions

• Continuous mode protection using demagnetization detection

• Accurate overvoltage protection (OVP)

• General-purpose input for latched protection; for use with system overtemperature

protection (OTP)

• Driver maximum on-time protection

Applications

• Applications requiring efficient and cost-effective power supply solutions up to 75 W