The iper12a combines a dedicated current mode pwm controller and a high voltage power mosfet on the same silicon.
Typical applications include battery charger power adapters, backup power for TVs or monitors, auxiliary supplies for motor control, etc.
Internal control circuitry provides the following benefits: large input voltage range on the V pin to accommodate changes in auxiliary supply voltage (a feature ideal for battery charger adapter configurations), automatic burst mode at low load conditions and in hiccup mode overvoltage protection. Due Diligence Block Diagram

Rectangular UI Output Features 4 Rectangular UI Output Features

Rectangular ui output characteristic of battery charger

A complete regulation scheme enables combined, precise output characteristics. Secondary feedback is provided through an optocoupler driven by the TSM101 . The device provides two op amps and a voltage reference, allowing the output voltage and current to be regulated. An integration or function performs the combination of two faulty signals, resulting in double voltage and current limiting, known as the rectangular output characteristic. This power supply is particularly suitable for battery chargers, where the output is primarily used in current mode to provide a specified charge rate. Accurate voltage regulation also facilitates the need for both modes of operation for Li-ion batteries.
Wide voltage range
5 wide V range 5 wide V range due diligence voltage
The V pin voltage range extends from 9 V to 38 V. This feature provides great flexibility in design to implement various behaviors. In the forward configuration, two advantages have been chosen for the device: Due Diligence Page 7 Figure 4
When the device starts switching, it immediately receives some energy from the auxiliary winding. So c5 can be reduced and a small ceramic chip (100nf) is enough to ensure filtering. The total start-up time from when the input voltage is turned on to when the output voltage is present is significantly reduced.
●The output current characteristic can be maintained even if the output voltage is very low or zero. Since the TSM101 is also powered in forward mode, it maintains current regulation regardless of the output voltage. The V pin voltage can vary as much as the input voltage, that is, a ratio of about 4 for a wide range of applications. How the Due Diligence Feedback Pin Works

How the Feedback Pin Works 6 How the Feedback Pin Works The Feedback pin controls the operation of the device. Unlike traditional PWM control circuits that use a voltage input (the inverting input of an op amp), the FB pin is sensitive to current. The internal current mode structure is given.
Internal current control structure

The overall DC transfer function can then be established between i and i as shown. This figure also takes into account the internal blanking time and its associated minimum turn-on time. This creates a minimum drain current at which the device can no longer control it in a linear fashion. This leakage current depends on the primary inductance value of the transformer and the input voltage. Depending on the current value above and the fixed value of 50 mA, two situations are possible.

The device includes a high voltage startup current source connected to the drain of the device. This startup current source is activated as long as V is below V once a voltage is applied to the input of the converter. When V is reached, the startup current source is turned off and the device starts to work by turning its main power mosfet on and off. Since the fb pin does not receive any current from the optocoupler, the device operates at full current capacity and the output voltage rises until it reaches the regulation point where the secondary loop starts sending current in the optocoupler. At this point, the converter enters regulation and the FB pin receives the amount of current required to deliver the correct power on the secondary side. Due Diligence DDONDDON
This sequence is shown. Note that during the actual start-up phase T, the device consumes some energy from the V capacitor, waiting for the auxiliary winding to provide continuous power. If the value of this capacitor is too low, the start-up phase is terminated and the converter never starts before any energy is received from the auxiliary winding. This is also indicated by a dashed line in the same figure. Figure 7 SS Due Diligence Overvoltage Thresholds

Over Voltage Threshold 8 Over Voltage Threshold
An overvoltage detector on the V pin allows the Viper12A to reset itself when V exceeds V. As shown in , it shows the entire sequence of overvoltage events. Note that this event only locks for the time required for V to reach V, after which the device automatically resumes normal operation. Due Diligence Due Diligence DDoS Figure 8. Due Diligence DDoS Overvoltage Sequence