FEATURES

► Current mode controller for active clamp forward topology

► Integrated 5 kV (wide body SOIC package) or 3.0 kV (LGA package) rated dielectric isolation voltage with Analog Devices, Inc., patented iCoupler technology

► Wide voltage supply range

► Primary VIN: up to 60 V

► Secondary VDD2: up to 36 V

► Integrated 1 A primary side MOSFET driver for power switch and active clamp reset switch

► Integrated 1 A secondary side MOSFET drivers for synchronous rectification

► Integrated error amplifier and <1% accurate reference voltage

► Programmable slope compensation

► Programmable frequency range: 50 kHz to 600 kHz typical

► Frequency synchronization

► Programmable maximum duty cycle limit

► Programmable soft start

► Smooth soft start from precharged load

► Programmable dead time

► Power saving light load mode using MODE pin

►Protection features such as short circuit, output overvoltage, and overtemperature protection

► Cycle-by-cycle input overcurrent protection

► Precision enable UVLO with hysteresis

► PGOOD pin for system flagging

► Tracking function from secondary side

 

 ANWENDUNGEN

► Isolated dc-to-dc power conversion

► Intermediate bus voltage generation

► Telecom, industrial

► Base station and antenna RF power

► Small cell

► PoE powered device

► Enterprise switches/routers

► Core/edge/metro/optical routing

► Power modules

 

ALLGEMEINE BESCHREIBUNG

The ADP1074 is a current mode, fixed frequency, active clamp, synchronous forward controller designed for isolated dc to dc power supplies. Analog Devices proprietary iCouplers® are integrated in the ADP1074 to eliminate the bulky signal transformers and optocouplers that transmit signals over the isolation boundary. Integrating the iCouplers reduces system design complexity, cost, and component count and improves overall system reliability. With the integrated isolators and metal-oxide semiconductor field effect transistor (MOSFET) drivers on both the primary and the secondary side, the ADP1074 offers a compact system level design and yields a higher efficiency than a nonsynchronous forward converter at heavy loads.

The primary side pins provide functions for programming the switching frequency, maximum duty cycle, external frequency synchronization, and slope compensation.

The secondary side pins provide functions for differential output voltage sensing, overvoltage, power good, tracking, and programmable light load mode setting.

The feedback signal and timing of synchronous rectifier pulse-width modulations (PWMs) are transmitted from primary to secondary or from secondary to primary sides through the iCouplers using a proprietary transmission scheme.

The ADP1074 also offers features such as input current protection, undervoltage lockout (UVLO), precision enable with adjustable hysteresis, overtemperature protection (OTP), and power saving light load mode (LLM).

 

ARBEITSTHEORIE

The ADP1074 is a current mode, fixed frequency, active clamp, synchronous forward controller designed for isolated dc to dc power supplies. Analog Devices proprietary iCouplers are integrated in the ADP1074 to eliminate the bulky signal transformers and optocouplers that transmit signals over the isolation boundary. Integrating the iCouplers reduces system design complexity, cost, and component count and improves overall system reliability. With the integrated isolators and MOSFET drivers on both the primary and the secondary side, the ADP1074 offers a compact system level design and yields a higher efficiency than a nonsynchronous forward converter at heavy loads.

Traditionally in a forward or flyback converter, a discrete optocoupler is used in the feedback path to transmit the signal from the secondary to the primary side, and an external transformer is used for transmitting the PWM signal from the primary to the secondary side for synchronous rectification. However, the current transfer ratio (CTR) of the optocouplers degrades over time and over temperature and so the optocoupler must be replaced every five to ten years, depending on the manufacturing quality and optocoupler grade that determines the initial CTR. The ADP1074 eliminates the use of optocouplers and signal transformers, thus reducing system cost, PCB area, and complexity while improving system reliability, without the issue of CTR degradation of the optocouplers.

The ADP1074 controller offers a complete solution for an isolated dc to dc power supply by integrating the 5 kV isolators and the primary and secondary control circuitries in one package.