Texas Instruments

The UCC35701/UCC35702 family of pulse width modulators is intended for isolated switching power supplies using primary side control. They can be used for both off-line applications and DC/DC converter designs such as in a distributed power system architecture or as a telecom power source. The devices feature low startup current, allowing for efficient off-line starting, yet have sufficient output drive to switch power MOSFETs in excess of 500kHz. Voltage feed forward compensation is operational over a 5:1 input range and provides fast and accurate response to input voltage changes over a 4:1 range. An accurate volt-second clamp and maximum duty cycle limit are also featured. Fault protection is provided by pulse by pulse current limiting as well as the ability to latch off after a programmable number of repetitive faults has occurred. Two UVLO options are offered. UCC35701 family has turn-on and turn-off thresholds of 13V/9V and UCC35702 family has thresholds of 9.6V/8.8V. The UCC35701/2 and the UCC25701/2 are offered in the 14 pin SOIC (D), 14 pin PDIP (N) or in 14 pin TSSOP (PW) packages. The UCC15701/2 is offered in the 14 pin CDIP (J) package. The UCC35701/UCC35702 family of pulse width modulators is intended for isolated switching power supplies using primary side control. They can be used for both off-line applications and DC/DC converter designs such as in a distributed power system architecture or as a telecom power source. The devices feature low startup current, allowing for efficient off-line starting, yet have sufficient output drive to switch power MOSFETs in excess of 500kHz. Voltage feed forward compensation is operational over a 5:1 input range and provides fast and accurate response to input voltage changes over a 4:1 range. An accurate volt-second clamp and maximum duty cycle limit are also featured. Fault protection is provided by pulse by pulse current limiting as well as the ability to latch off after a programmable number of repetitive faults has occurred. Two UVLO options are offered. UCC35701 family has turn-on and turn-off thresholds of 13V/9V and UCC35702 family has thresholds of 9.6V/8.8V. The UCC35701/2 and the UCC25701/2 are offered in the 14 pin SOIC (D), 14 pin PDIP (N) or in 14 pin TSSOP (PW) packages. The UCC15701/2 is offered in the 14 pin CDIP (J) package.

The UCC35705 and UCC35706 devices are 8-pin voltage mode primary side controllers with fast over-current protection. These devices are used as core high-speed building blocks in high performance isolated and non-isolated power converters. UCC35705/UCC35706 devices feature a high speed oscillator with integrated feed-forward compensation for improved converter performance. A typical current sense to output delay time of 25 ns provides fast response to overload conditions. The IC also provides an accurate programmable maximum duty cycle clamp for increased protection which can also be disabled for the oscillator to run at maximum possible duty cycle. Two UVLO options are offered. The UCC35705 with lower turn-on voltage is intended for dc-to-dc converters while the higher turn-on voltage and the wider UVLO range of the UCC35706 is better suited for offline applications. The UCC35705/UCC35706 family is offered in 8-pin MSOP (DGK), SOIC (D) and PDIP (P) packages. The UCC35705 and UCC35706 devices are 8-pin voltage mode primary side controllers with fast over-current protection. These devices are used as core high-speed building blocks in high performance isolated and non-isolated power converters. UCC35705/UCC35706 devices feature a high speed oscillator with integrated feed-forward compensation for improved converter performance. A typical current sense to output delay time of 25 ns provides fast response to overload conditions. The IC also provides an accurate programmable maximum duty cycle clamp for increased protection which can also be disabled for the oscillator to run at maximum possible duty cycle. Two UVLO options are offered. The UCC35705 with lower turn-on voltage is intended for dc-to-dc converters while the higher turn-on voltage and the wider UVLO range of the UCC35706 is better suited for offline applications. The UCC35705/UCC35706 family is offered in 8-pin MSOP (DGK), SOIC (D) and PDIP (P) packages.

The UCC3580 family of PWM controllers is designed to implement a variety of active clamp/reset and synchronous rectifier switching converter topologies. While containing all the necessary functions for fixed frequency, high performance pulse width modulation, the additional feature of this design is the inclusion of an auxiliary switch driver which complements the main power switch, and with a programmable deadtime or delay between each transition. The active clamp/reset technique allows operation of single ended converters beyond 50% duty cycle while reducing voltage stresses on the switches, and allows a greater flux swing for the power transformer. This approach also allows a reduction in switching losses by recovering energy stored in parasitic elements such as leakage inductance and switch capacitance. The oscillator is programmed with two resistors and a capacitor to set switching frequency and maximum duty cycle. A separate synchronized ramp provides a voltage feedforward pulse width modulation and a programmed maximum volt-second limit. The generated clock from the oscillator contains both frequency and maximum duty cycle information. The main gate drive output (OUT1) is controlled by the pulse width modulator. The second output (OUT2) is intended to activate an auxiliary switch during the off time of the main switch, except that between each transition there is deadtime where both switches are off, programmed by a single external resistor. This design offers two options for OUT2, normal and inverted. In the -1 and -2 versions, OUT2 is normal and can be used to drive PMOS FETs. In the -3 and -4 versions, OUT2 is inverted and can be used to drive NMOS FETs. In all versions, both the main and auxiliary switches are held off prior to startup and when the PWM command goes to zero duty cycle. During fault conditions, OUT1 is held off while OUT2 operates at maximum duty cycle with a guaranteed off time equal to the sum of the two deadtimes. Undervoltage lockout monitors supply voltage (VDD), the precision reference (REF), input line voltage (LINE), and the shutdown comparator (SHTDWN). If after any of these four have sensed a fault condition, recovery to full operation is initiated with a soft start. VDD thresholds, on and off, are 15V and 8.5V for the -2 and -4 versions, 9V and 8.5V for the -1 and -3 versions. The UCC1580-x is specified for operation over the military temperature range of –55°C to 125°C. The UCC2580-x is specified from –40°C to 85°C. The UCC3580-x is specified from 0°C to 70°C. Package options include 16-pin surface mount and dual in-line. The UCC3580 family of PWM controllers is designed to implement a variety of active clamp/reset and synchronous rectifier switching converter topologies. While containing all the necessary functions for fixed frequency, high performance pulse width modulation, the additional feature of this design is the inclusion of an auxiliary switch driver which complements the main power switch, and with a programmable deadtime or delay between each transition. The active clamp/reset technique allows operation of single ended converters beyond 50% duty cycle while reducing voltage stresses on the switches, and allows a greater flux swing for the power transformer. This approach also allows a reduction in switching losses by recovering energy stored in parasitic elements such as leakage inductance and switch capacitance. The oscillator is programmed with two resistors and a capacitor to set switching frequency and maximum duty cycle. A separate synchronized ramp provides a voltage feedforward pulse width modulation and a programmed maximum volt-second limit. The generated clock from the oscillator contains both frequency and maximum duty cycle information. The main gate drive output (OUT1) is controlled by the pulse width modulator. The second output (OUT2) is intended to activate an auxiliary switch during the off time of the main switch, except that between each transition there is deadtime where both switches are off, programmed by a single external resistor. This design offers two options for OUT2, normal and inverted. In the -1 and -2 versions, OUT2 is normal and can be used to drive PMOS FETs. In the -3 and -4 versions, OUT2 is inverted and can be used to drive NMOS FETs. In all versions, both the main and auxiliary switches are held off prior to startup and when the PWM command goes to zero duty cycle. During fault conditions, OUT1 is held off while OUT2 operates at maximum duty cycle with a guaranteed off time equal to the sum of the two deadtimes. Undervoltage lockout monitors supply voltage (VDD), the precision reference (REF), input line voltage (LINE), and the shutdown comparator (SHTDWN). If after any of these four have sensed a fault condition, recovery to full operation is initiated with a soft start. VDD thresholds, on and off, are 15V and 8.5V for the -2 and -4 versions, 9V and 8.5V for the -1 and -3 versions. The UCC1580-x is specified for operation over the military temperature range of –55°C to 125°C. The UCC2580-x is specified from –40°C to 85°C. The UCC3580-x is specified from 0°C to 70°C. Package options include 16-pin surface mount and dual in-line.

The UCC3581 voltage mode pulse width modulator is designed to control low power isolated DC - DC converters in applications such as Subscriber Line Power (ISDN I.430). Primarily used for single switch forward and flyback converters, the UCC3581 features BiCMOS circuitry for low startup and operating current, while maintaining the ability to drive power MOSFETs at frequencies up to 100kHz. The UCC3581 oscillator allows the flexibility to program both the frequency and the maximum duty cycle with two resistors and a capacitor. A TTL level input is also provided to allow synchronization to an external frequency source. The UCC3581 includes programmable soft start circuitry, overcurrent detection, a 7.5V linear preregulator to control chip VDD during startup, and an on-board 4.0V logic supply. The UCC3581 provides functions to maximize light load efficiency that are not normally found in PWM controllers. A linear preregulator driver in conjunction with an external depletion mode N-MOSFET provides initial controller power. Once the bootstrap supply is functional, the preregulator is shut down to conserve power. During light load, power is saved by providing a programmable minimum duty cycle clamp. When a duty cycle below the minimum is called for, the modulator skips cycles to provide the correct average duty cycle required for output regulation. This effectively reduces the switching frequency, saving significant gate drive and power stage losses. The UCC3581 is available in 14-pin plastic and ceramic dual-in-line packages and in a 14-pin narrow body small outline IC package (SOIC). The UCC1581 is specified for operation from –55°C to +125°C, the UCC2581 is specified for operation from –40°C to +85°C, and the UCC3581 is specified for operation from 0°C to +70°C. The UCC3581 voltage mode pulse width modulator is designed to control low power isolated DC - DC converters in applications such as Subscriber Line Power (ISDN I.430). Primarily used for single switch forward and flyback converters, the UCC3581 features BiCMOS circuitry for low startup and operating current, while maintaining the ability to drive power MOSFETs at frequencies up to 100kHz. The UCC3581 oscillator allows the flexibility to program both the frequency and the maximum duty cycle with two resistors and a capacitor. A TTL level input is also provided to allow synchronization to an external frequency source. The UCC3581 includes programmable soft start circuitry, overcurrent detection, a 7.5V linear preregulator to control chip VDD during startup, and an on-board 4.0V logic supply. The UCC3581 provides functions to maximize light load efficiency that are not normally found in PWM controllers. A linear preregulator driver in conjunction with an external depletion mode N-MOSFET provides initial controller power. Once the bootstrap supply is functional, the preregulator is shut down to conserve power. During light load, power is saved by providing a programmable minimum duty cycle clamp. When a duty cycle below the minimum is called for, the modulator skips cycles to provide the correct average duty cycle required for output regulation. This effectively reduces the switching frequency, saving significant gate drive and power stage losses. The UCC3581 is available in 14-pin plastic and ceramic dual-in-line packages and in a 14-pin narrow body small outline IC package (SOIC). The UCC1581 is specified for operation from –55°C to +125°C, the UCC2581 is specified for operation from –40°C to +85°C, and the UCC3581 is specified for operation from 0°C to +70°C.