Module spare parts UAA326A02

Brand Name

ABB

Model Number

UAA326A02

Focus on DCS, PLC, robot control system and large servo system.

Main products: various modules / cards, controllers, touch screens, servo drivers.

Advantages: supply of imported original products, professional production parts,

Fast delivery, accurate delivery time,

The main brands include ABB Bailey, Ge / fuanc, Foxboro, Invensys Triconex, Bently, A-B Rockwell, Emerson, ovation, Motorola, xyvom, Honeywell, Rexroth, KUKA, Ni, Deif, Yokogawa, Woodward, Ryan, Schneider, Yaskawa, Moog, prosoft and other brands

UAA326A02

The LM3481 device uses a fixed frequency, Pulse Width Modulated (PWM), current mode control architecture. In a typical application circuit, the peak current through the external MOSFET is sensed through an external sense resistor. The voltage across this resistor is fed into the ISEN pin. This voltage is then level shifted and fed into the positive input of the PWM comparator. The output voltage is also sensed through an external feedback resistor divider network and fed into the error amplifier (EA) negative input (feedback pin, FB). The output of the error amplifier (COMP pin) is added to the slope compensation ramp and fed into the negative input of the PWM comparator. At the start of any switching cycle, the oscillator sets the RS latch using the SET/Blank-out and switch logic blocks. This forces a high signal on the DR pin (gate of the external MOSFET) and the external MOSFET turns on. When the voltage on the positive input of the PWM comparator exceeds the negative input, the RS latch is reset and the external MOSFET turns off. The voltage sensed across the sense resistor generally contains spurious noise spikes, as shown in Figure 18. These spikes can force the PWM comparator to reset the RS latch prematurely. To prevent these spikes from resetting the latch, a blank-out circuit inside the IC prevents the PWM comparator from resetting the latch for a short duration after the latch is set. This duration, called the blank-out time, is typically 250 ns and is specified as tmin (on) in the Electrical Characteristics section. Under extremely light load or no-load conditions, the energy delivered to the output capacitor when the external MOSFET is on during the blank-out time is more than what is delivered to the load. An overvoltage comparator inside the LM3481 prevents the output voltage from rising under these conditions by sensing the feedback (FB pin) voltage and resetting the RS latch. The latch remains in a reset state until the output decays to the nominal value. Thus the operating frequency decreases at light loads, resulting in excellent efficiency.