IP1845A

• Guaranteed ±1% reference voltage tolerance
• Accurate oscillator discharge current
• Guaranteed ±10% frequency tolerance
• Low startup current (<500 mA)
• Under voltage lockout with hysteresis
• Output state completely defined for all supply and input conditions
• Interchangeable with IP and UC1844/5 series for improved operation
• 500kHz Oscillator operation 250kHz Output operation

The IP1844A/IP1845A series of switching regulator control circuits contain all the functions necessary to implement off-line, current mode switching regulators, using a minimum number of external parts. Functions included are voltage reference, error amplifier, current sense comparator, oscillator, totem-pole output driver and under-voltage lockout circuitry.

In addition the IP1844A and IP1845A series of devices have a toggle flip-flop which blanks the output on every second clock pulse, thereby ensuring that the duty cycle never exceeds 50%. For applications requiring more flexible control, all devices feature an on-chip trimmed oscillator discharge current, allowing accurate control to maximum-duty-cycle by selection of timing components. This can be beneficial even when using the IP1844A or IP1845A series, as it allows optimum safety margins to be designed into the application.

Although pin compatible with the standard IP1844/5 parts these devices offer improved performance in several areas. They also offer tighter specification and improved performance over the IP and UC1844/5 series, whilst retaining complete compatibility.