Product category:
Power Supply ICs and Controllers
News Release from: Allegro MicroSystems Europe | Subject: A8450
Edited by the Electronicstalk Editorial
Team on 04 February 2005
Automotive regulator chip has multiple
outputs
The new A8450 is a multi-output voltage regulator integrated circuit designed for automotive applications.
The new A8450 is a multi-output voltage regulator integrated circuit designed for automotive applications It operates from a wide input supply range of 6-45V, and is rated for operation over the temperature range from -40 to +135C
This article was originally published on Electronicstalk on 30 Aug 2000 at 8.00am (UK)
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The device incorporates a DC/DC convertor with an output of 5.7V and two 5V medium-power linear regulators.
Two additional linear outputs - a 3.3V supply and a 1.2-3.3V adjustable regulator - can be implemented with external transistors.
The A8450 has been designed to meet the requirement for greater circuit integration in power management ICs.
As well as the facility for multiple outputs, such highly integrated devices offer improved reliability and manufacturability, ease of design for specific applications, and integrated fault detection and reset.
In the A8450, the DC/DC convertor is implemented as a current-variable-frequency buck regulator with a soft-start feature to ramp up the output voltage with minimum stress on the device and power supply.
An internal charge pump provides gate drive for an N-channel DMOS buck transistor.
At input voltages below 12 V, the off time is scaled down, keeping the switching frequency within a reasonable range and minimising the ripple current.
The two medium-power 5V linear regulators feature foldback current limiting in the event of a short-circuited load.
The outputs track each other to within 0.5% under normal steady-state operating conditions.
Two additional linear outputs, a constant 3.3V and an adjustable 1.2-3.3V, can be implemented with external NPN pass transistors.
An additional pin for each regulator is available to set a current limit.
Two enable pins allow the device to be put into sleep mode by disabling all internal circuitry.
When coming out of sleep mode, the device will wait until the charge pump has stabilised before allowing the switch-mode convertor to operate, a process that typically takes 300us.
Other features include ignition switch enable, 100% duty-cycle operation for low input voltages, overtemperature fault flag output and a power-on reset function.
The A8450 is supplied in a 24-pin SOIC power package.
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