LAD-120 series is a low–cost power supply with UPS function from MEAN WELL


In some applications, one of the urgent tasks in creating a power supply system is to ensure continuity or uninterrupted power supply. Such power supply systems are called UPS, from the English Uninterruptible Power Supply – an uninterruptible power supply. In cases where the power supply of end systems is provided by a DC voltage source, such a power supply unit is commonly called a UPS PSU if it provides for the connection of a rechargeable battery as an auxiliary power source. In the development of the series of popular power supplies with the UPS function of the AD series, MEAN WELL has developed new series of LAD power supplies.

The LAD-120 series power supply unit is a closed-type AC/DC converter in a technological protective housing, with a DC UPS function, with monitoring of the state of the external network and the battery. The output voltage is set for the use and charging of rechargeable batteries – 12, 24, 36, 48V (nominal value); the type of batteries used is lead–acid and lithium-ion; the rated power of the power supplies in the series is 120W.

Внешний вид блока питания с UPS функцией серии LAD-120The appearance of the power supply unit with UPS function of the LAD-120 series

LAD-120 power supplies can operate in two main modes:

  • The load power supply and battery charger are separated (connection via separate channels).
  • A power supply with UPS function when the load is powered by a rechargeable battery when power is lost from an external AC network.
The UPS mode is turned on forcibly by installing a jumper between pins 7, 8 (Pin7, Pin8) on the CN2 connector (Forced start UPS mode). By default (without a jumper installed), the two channels (main load and battery charge power supply) work separately, and switching the load power from the battery does not occur when the external network is lost! The Функционал источников питания серии LAD-120functionality of LAD-120 series power supplies

The distinctive features of the LAD-120 series power supplies are – built-in battery charger; two modes of operation of the power supply; all basic types of protection: from short circuit, overload, overvoltage, overheating, deep discharge of the battery and reverse polarity when connecting the battery. The output voltage of each model in the series is optimized for the use of rechargeable batteries – 13.8V (nominal 12V), 27.6V (nominal 24V), 41.5V (nominal 36V), 55.2V (nominal 48V) – through the main channel and the battery connection channel (charge). The main channel has a voltage level adjustment in the range -20%...+5%.

LAD-120 power supplies have a wide range of status monitoring outputs: external network (AC OK) and battery (Battery Disconnect/Reverse Polarity, Battery Low, Battery Full, Discharge). All signal outputs of the LAD-120 power supply are TTL compatible, and are organized according to the "Open Collector" type, that is, they require mandatory connection to the circuit of an external power source and a pull-up resistor/load. The maximum allowable current through each contact is 30mA at a maximum voltage of 50V (DC):

Подключение сигнальной цепи TTL в источнике питания LAD-120Connecting the TTL signal circuit in the LAD-120 power supply

For maintenance and health monitoring, two switches are located on the housing of the LAD-120 power supplies – an external AC network (AC ON/OFF) and battery connection (Bat.ON/OFF), completely disconnecting external power and battery power.

LAD-120 series power supplies can be used as an embedded uninterruptible power supply in fire safety and evacuation systems, emergency lighting, loudspeaker warning, security systems, monitoring, industrial automation and other applications.

Main technical characteristics and features of LAD-120 series power supplies

  • Extended input voltage range: 90...264V (AC), 127...370V (DC).
  • Rated output power: 120W.
  • Output voltages according to models in the series: 13.8, 27.6, 41.5, 55.2V.
  • Number of channels: two – main (load connection) and battery connection.
  • Maximum battery charge current: 1A.
  • Operating modes: power supply and charger; power supply with UPS function.
  • Status Monitoring: TTL signals – AC OK, Battery Disconnect/Reverse Polarity, Battery Low, Battery Full, Discharge.
  • Separate switches on the power supply: main power supply AC, battery.
  • Protection: against short circuit, overload, overvoltage, overheating, reverse polarity when connecting the battery, deep discharge of the battery.
  • Types of batteries used: lead-acid, lithium-ion.
  • Extended operating temperature range: -20°C to +60°C.
  • Cooling due to natural ventilation.
  • The warranty period is 3 years.

In more detail, the technical characteristics and features of power supplies with the LAD-120 series UPS function are presented in the Specifications on the product page. For advice or clarification of information on MEAN WELL power supplies, you can contact us by e-mail .