Power Integrations Adds to its LinkSwitch-TN2 AC-DC Buck Converter FamilyApril 01, 2021 by Gary Elinoff
The new unit is pin for pin compatible with previous family members, and offers an output current fully 60% higher.
The LNK3207 is the latest member of Power Integrations’ LinkSwitch-TN2 AC-DC converter family. Its available output current of 575 mA represents a 60% improvement over the 360 mA possible with the LNK3206.
The LNK3207. Image courtesy of Power Integrations
The LNK3207 is an AC-DC buck converter IC that delivers 80% efficiency and better while consuming less than 30 mW during no-load conditions. The units also feature an internal oscillator and on/off control for high efficiency at light load
The monolithic IC incorporates a 725 V power MOSFET to better withstand voltage surges. The related LNK320x units feature a 900 internal MOSFET.
As per Silvestro Fimiani, product marketing manager at Power Integrations, “These new LinkSwitch-TN2 ICs are pin-to-pin compatible with previous generations, making it simple for customers to upgrade to higher-power designs. A high-current buck converter can be created using a minimal number of easily available components while saving at least one diode over previous solutions.”
The family members support buck, buck-boost and flyback implementations. MOSFET current limit modes can are chosen through an external capacitor’s value. The unit switches at 66 kHz, allowing designs to employ small sized, low cost inductors and smaller valued filter capacitors, saving size and weight for OEMs
The LinkSwitch devices’ oscillators include circuitry to to introduce a typical 4 kHz of frequency jitter, which serves to reduce EMI. The modulation rate of the jitter is set to 1 kHz, which serves to optimize EMI reduction for quasi-peak and average emissions.
Safety and Reliability
Fault conditions for the LNK3207 include:
- Protection from line overvoltage (OVL)
- Protection from output overvoltage (OVP)
- Overtemperature protection (OTP)
LinkSwitch devices enter into auto-restart in response to a fault condition. For the first time a fault is noted, MOSFET off-time is 150 ms. If the condition persists, the next off-time is 1500 ms.
Another important safety feature for the converter is the extra creepage between all other pins and the drain. This provides improved reliability for the device.
Standby current is spec'd at under 100 µA, and with external bias, rated no-load consumption of less than 30 mW is achieved. Constant efficiency over a wide load range is provided by on/off control.
Aimed at Mass-Market Household Appliances
The new LinkSwitch ICs are aimed at mass-market appliances such as coffee makers, washers and dryers. To back up its assertion, Power Integrations highlights its RDR reference design.
The RDR-912 reference design. Image courtesy of Power Integrations
A representative application of use to OEMs, the RDR-912 details a 6.6 watt non-isolated buck converter aimed at small appliances. Input is 85 to 265 VAC, output is 12 VDC at 550 mA.
- Home and building automation
- Smart LED drivers and industrial controls
Operating junction temperature range is from -40 to +150 °C
The LNK3207 and other member of Power Integrations’ LinkSwitch AC-DC converter family are available in either
- PDIP-8C (P package)
- SMD-8C (G package)
- SO-8C (D package)