3-A Wide-input Adjustable Switching Regulator Schematic Circuit Diagram
The PTN78060 is a series of high-efficiency, buck-boost, integrated switching regulators (ISR) from good old Texas Instruments (TI). The caseless, double-sided package has excellent thermal characteristics and is RoHS compliant. The PTN78060 devices °Orate from a remarkably wide input voltage range:
Note that the —A version supplies a negative output voltage. The devices provide high-efficiency step-down voltage conversion for loads of up to 3 A.
The PTN78060 devices are suited to a wide variety of general-purpose applications that operate off 12-V, 24-V, or tightly regulated 28-V dc power, hence are ideal for running low-voltage electronics from a very high-power 24-V battery unit salvaged from an electric wheelchair and migrated into a robot.
The output voltage Vo can be set to any value over a wide adjustment range using a single external resistor RsET, using the equation
RSET = 54.9kL2x(1.25V/Vo-VmiN) – Rp
If pin 4 is left open, the output voltage defaults to the lowest value. Limiting ourselves to the two positive-output regulators, for the -W version, VMIN, and Rp are 2.5 V and 6.49 kfl respectively; for the -H device, the values 11.824 V and 6.65 kfl should be used. For the output to remain in regulation, the input voltage must exceed the output by a minimum differential voltage. Another consideration is the pulse width modulation (PWM) range of the regulator’s inter-nal control circuit. For stable operation, its operating duty cycle should not be lower than a certain minimum percentage. This defines the maximum advisable ratio between the regulator input and output voltage magnitudes. For satisfactory performance, the operating input voltage range of the PTN78060x must satisfy the following requirements.
1. For PTN78060W devices supplying output voltages lower than 10 V, the minimum input voltage is (V0+2 V) or 7 V, whichever is higher.
