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 nega-tive 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 applica-tions 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 wheel chair and migrated into a robot.
RSET = 54.9kL2x(1.25V/Vo-VmiN) – Rp
If pin 4 is left open, the output voltage defaults to the lowest value. Limiting our-selves to the two positive-output regula-tors, 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 pulsewidth modula-tion (PWM) range of the regulators 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 operat-ing 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.