UC3844A

UC3844 : The UCx84x series of control integrated circuits provide the features that are necessary to implement off-line or DC-to-DC fixed-frequency current-mode control schemes, with a minimum number of external components. The internally implemented circuits include an undervoltage lockout (UVLO), featuring a start-up current of less than 1 mA, and a precision reference trimmed for accuracy at the error amplifier input. Other internal circuits include logic to ensure latched operation, a pulse-width modulation (PWM) comparator that also provides current-limit control, and a totem-pole output stage that is designed to source or sink high-peak current. The output stage, suitable for driving N-channel .

UC3844 : The UTC UC3844/3845 are high performance fixed frequency current mode controllers that specifically designed for Off-Line and DC to DC converter applications with minimal external parts count. The differences between UC3844 and UC3845 are the maximum duty cycle ranges and under-voltage lockout thresholds. The UC3844 ideally suited to off-line applications with UVLO thresholds of 16V(ON) and 10V(OFF), and UC3845 has UVLO thresholds of 8.5V(ON) and 7.6V(OFF) for lower voltage applications.  FEATURES * Operation output switching frequency up to 500 kHz * Automatic feed forward compensation * Latching PWM for cycle-by-cycle current limiting * High current totem pole output * Internally trimmed.

UC3844 : UC3844, UC3845, UC2844, UC2845 High Performance Current Mode Controllers The UC3844, UC3845 series are high performance fixed frequency current mode controllers. They are specifically designed for Off−Line and DC−to−DC converter applications offering the designer a cost effective solution with minimal external components. These integrated circuits feature an oscillator, a temperature compensated reference, high gain error amplifier, current sensing comparator, and a high current totem pole output ideally suited for driving a power MOSFET. Also included are protective features consisting of input and reference undervoltage lockouts each with hysteresis, cycle−by−cycle current limiting, a latc.

UC3844 : TheUC3842/3/4/5family of controlICs provides the necessary features to implement off-line or DC to DC fixed frequency current mode control schemes with a minimal externalparts count.Internallyimplementedcircuits include undervoltagelockout featuring start-up current less than 1 mA, a precision reference trimmed for accuracy at the error amp input, logic to insure latched operation, a PWM comparatorwhich also providescurrentlimit control,and a totem pole output stage designed to source or sink high peak current. The output stage, suitable for driving N-Channel MOSFETs, is low in theoff-state. Differences between members of this family are the under-voltage lockout thresholds and maximum duty.

UC3844 : The UC3842/UC3843/UC3844/UC3845 are fixed frequencycurrent-mode PWM controller. They are specially designed for Off-Line and DC to DC converter applications with minimum external components. These integrated circuits feature a trimmed oscillator for precise duty cycle control, a temperature compensated reference, high gain error amplifier, current sensing comparator and a high current totempole output for driving a Power MOSFET. The UC3842 and UC3844 have UVLO thresholds of 16V (on) and 10V (off). The UC3843 and UC3845 are 8.5V(on) and 7.9V (off). The UC3842 and UC3843 can operate within 100% duty cycle. The UC3844 and UC3845 can operate with 50% duty cycle. 8-DIP 8-SOP 1 1 14-SOP 1 Int.

UC3844A : PThe UC384xA family of control ICs provides the necessary features to implement off-line or DC to teDC fixed frequency current mode control schemes lewith a minimal external parts count. Internally imoplemented circuits include a trimmed oscillator for sprecise DUTY CYCLE CONTROL under voltage blockout featuring start-up current less than 0.5mA, Oa precision reference trimmed for accuracy at the -error amp input, logic to insure latched operation, )a PWM comparator which also provides current t(slimit control, and a totem pole output stage decsigned to source or sink high peak current. The uoutput stage, suitable for driving N-Channel MOSdFETs, is low in the off-state. UC2842AD1; UC3842AD1;.

UC3844A : The UC184xA family of control ICs provides all the necessary features to implement off-line fixed-frequency, current-mode switching power supplies with a minimum of external components. The current mode architecture demonstrates improved load regulation, pulse-by-pulse current limiting and inherent protection of the power supply output switch. The IC includes: A bandgap reference trimmed to ±1% accuracy, an error amplifier, a current sense comparator with internal clamp to 1V, a high current totem pole output stage for fast switching of power MOSFET's, and an externally programmable oscillator to set frequency and maximum duty cycle. The undervoltage lock-out is designed to operate with 25.

UC3844A : The UCx84xA family of control devices is a pin-for-pin compatible improved version of the UCx84x family. Providing the necessary features to control currentmode or switched-mode power supplies, this family of devices has many improved features: startup current is less than 0.5 mA, oscillator discharge is trimmed to 8.3 mA, and during UVLO, the output stage can sink at least 10 mA at less than 1.2 V for VCC over 5 V. Device Information(1) PART NUMBER PACKAGE BODY SIZE (NOM) UC1842A, UC1843A, UC1844A, UC1845A CDIP (8) LCCC (20) 6.67 mm × 9.60 mm 8.89 mm × 8.89 mm UC2843A PLCC (20) 8.96 mm × 8.96 mm UC2842A, UC2843A, UC2844A, UC2845A, UC3842A, UC3843A, UC3844A, UC3845A PDIP (8) SOIC.

UC3844A-BW : The UC3842A-BW/43A-BW/44A-BW/45A-BW are fixed frequency current mode PWM controller. They are specially designed for OFF−Line and DC to DC converter applications with a minimal external components. Internally implemented circuits include a trimmed PIN CONNECTION (TOP VIEW) oscillator for precise duty cycle control, a temperature compensated reference, high gain error amplifier, current sensing comparator, and a high current totempole output ideally suited for driving a power MOSFET. Protection circuitry includes built undervoltage lockout and current limiting. The UC3842A-BW and UC3844A-BW have UVLO thresholds of 16 V (on) and 10 V (off). The corresponding thresholds for the UC3843A-B.

UC3844B : UC3844B, UC3845B, UC2844B, UC2845B High Performance Current Mode Controllers The UC3844B, UC3845B series are high performance fixed frequency current mode controllers. They are specifically designed for Off−Line and dc−dc converter applications offering the designer a cost−effective solution with minimal external components. These integrated circuits feature an oscillator, a temperature compensated reference, high gain error amplifier, current sensing comparator, and a high current totem pole output ideally suited for driving a power MOSFET. Also included are protective features consisting of input and reference undervoltage lockouts each with hysteresis, cycle−by−cycle current limiting, a l.

UC3844B : The UC384xB family of control ICs provides the necessary features to implement off-line or DC to DC fixed frequency current mode control schemes with a minimal external parts count. Internally implemented circuits include a trimmed oscillator for precise DUTY CYCLE CONTROL under voltage lockout featuring start-up current less than 0.5mA, a precision reference trimmed for accuracy at the error amp input, logic to insure latched operation, a PWM Minidip SO8 comparator which also provides current limit control, and a totem pole output stage designed to source or sink high peak current. The output stage, suitable for driving N-Channel MOSFETs, is low in the offstate. Differences between membe.

UC3844B : UC3842B/3B/4B/5B,UC2842B/3B Package outline The UC3842B/3B/4B/5B, series are high performance fixed frequency current mode controllers. They are specifically designed for Off–Line and dc–to–dc converter applications offering the designer a cost–effective solution with minimal external components. These integrated circuits feature a trimmed oscillator for precise duty cycle control, a temperature compensated reference, high gain error amplifier, current sensing comparator, and a high current totem pole output ideally suited for driving a power MOSFET. Also included are protective features consisting of input and reference undervoltage lockouts each with hysteresis, cycle–by–cycle current li.

UC3844BN : The UC384xB family of control ICs provides the necessary features to implement off-line or DC to DC fixed frequency current mode control schemes with a minimal external parts count. Internally implemented circuits include a trimmed oscillator for precise DUTY CYCLE CONTROL under voltage lockout featuring start-up current less than 0.5mA, a precision reference trimmed for accuracy at the error amp input, logic to insure latched operation, a PWM Minidip SO8 comparator which also provides current limit control, and a totem pole output stage designed to source or sink high peak current. The output stage, suitable for driving N-Channel MOSFETs, is low in the offstate. Differences between membe.

UC3844D : The UC3842/UC3843/UC3844/UC3845 are fixed frequencycurrent-mode PWM controller. They are specially designed for Off-Line and DC to DC converter applications with minimum external components. These integrated circuits feature a trimmed oscillator for precise duty cycle control, a temperature compensated reference, high gain error amplifier, current sensing comparator and a high current totempole output for driving a Power MOSFET. The UC3842 and UC3844 have UVLO thresholds of 16V (on) and 10V (off). The UC3843 and UC3845 are 8.5V(on) and 7.9V (off). The UC3842 and UC3843 can operate within 100% duty cycle. The UC3844 and UC3845 can operate with 50% duty cycle. 8-DIP 8-SOP 1 1 14-SOP 1 Int.

UC3844D : TheUC3842/3/4/5family of controlICs provides the necessary features to implement off-line or DC to DC fixed frequency current mode control schemes with a minimal externalparts count.Internallyimplementedcircuits include undervoltagelockout featuring start-up current less than 1 mA, a precision reference trimmed for accuracy at the error amp input, logic to insure latched operation, a PWM comparatorwhich also providescurrentlimit control,and a totem pole output stage designed to source or sink high peak current. The output stage, suitable for driving N-Channel MOSFETs, is low in theoff-state. Differences between members of this family are the under-voltage lockout thresholds and maximum duty.

UC3844D : Order this document by UC3844/D UC3844, 45 UC2844, 45 High Performance Current Mode Controllers The UC3844, UC3845 series are high performance fixed frequency current mode controllers. They are specifically designed for Off–Line and dc–to–dc converter applications offering the designer a cost effective solution with minimal external components. These integrated circuits feature an oscillator, a temperature compensated reference, high gain error amplifier, current sensing comparator, and a high current totem pole output ideally suited for driving a power MOSFET. Also included are protective features consisting of input and reference undervoltage lockouts each with hysteresis, cycle–by–cycle .