VPC2842

VPCx84x is a high-performance current-mode universal PWM controller designed using advanced BCD semiconductor process technology, featuring low power consumption, fast current sampling, and a high programmable maximum operating frequency. Internally implemented circuits include: an undervoltage lockout (UVLO) with startup current as low as tens of microamps; a pulse-width modulation (PWM) fast comparator providing current limit control, with a total propagation delay from comparison to output as low as 30nS; a fast-comparison oscillator enabling a programmable maximum frequency of 1MHz; an error amplifier with a trim-calibrated ±1% precision reference at its non-inverting input; a push-pull output stage comprising NMOS and PMOS transistors capable of delivering output high levels equal to the device supply voltage; and additional internal logic circuitry ensuring latched operation. The VPCx84x series also incorporates an internal clamp circuit. As the VDD voltage of VPCx842/4 rises to approximately 19V (13V for VPCx843/5), its current gradually increases with the rising voltage until reaching a maximum of 14mA (typical) at 24.7V (19V for VPCx843/5). By appropriately designing the current-limiting resistor of the auxiliary supply, VDD voltage rise can be prevented when the auxiliary supply is excessive, avoiding exceeding the rated gate voltage of the power transistor. The VPCx84x is offered in multiple variants, differing primarily in temperature range, maximum duty cycle, and turn-on/turn-off threshold voltages. Devices with higher turn-on or turn-off hysteresis are ideal for off-line power supplies, while devices with a narrower hysteresis range are suited for DC-DC applications. The VPC284x operates over a temperature range of –40°C to 125°C, and the VPC384x operates over a temperature range of –25°C to 85°C. The VPCx84x series is a highly versatile PWM controller IC, suitable for implementing AC-DC or DC-DC fixed-frequency current-mode control schemes, as well as pulse generators. Integrated functions include UVLO, voltage reference, startup circuitry with less than 100uA, a ±1% precision reference for the error amplifier input, logic ensuring latched operation, a PWM comparator for current limit control, and an output stage comprising PMOS and NMOS transistors capable of sourcing or sinking high peak currents. The key differences among these series lie in the UVLO thresholds, acceptable ambient temperature range, and maximum duty cycle. The typical UVLO thresholds of 14.6V (ON) and 8.7V (OFF) on VPCx842 and VPCx844 devices make them suitable for off-line AC-DC applications. The corresponding typical thresholds of 8.5V (ON) and 7.7V (OFF) on VPCx843 and VPCx845 devices make them suitable for regulated input voltages used in DC-DC applications. VPCx842 and VPCx843 devices operate at duty cycles approaching 100%. VPCx844 and VPCx845 achieve a duty cycle range of 0% to 50% by adding an internal toggle flip-flop that blanks the output every other clock cycle. The recommended operating temperature range for VPC284x series devices is –40°C to 105°C, and for VPC384x series devices is –25°C to 85°C.

Applications

• Switching regulators of any polarity
• Transformer-coupled DC-DC converters
• BMS auxiliary power supply

Key features

• Startup current as low as 50uA, max 100uA
• Operating current only 2.7mA at 52kHz
• CS fast comparator with propagation delay as low as 30nS
• Maximum operating frequency 1MHz
• Error amplifier reference voltage with ±1% accuracy
• Rail-to-rail output OUT, with 1nF capacitor: output rise time 30nS, fall time 20nS, cycle-by-cycle current limiting
• Trimmed oscillator discharge current
• Built-in clamp absorption circuit