Austin, Texas - Motorola Inc. will come out of the gate this month with two ICs that manage the power capabilities of its Quicc I and II processors, which are popular processors in telecom, networking, cable modem and asymmetric digital subscriber line equipment designs.
The PC33701 power supply works with the Power Quicc I family while the PC33702 operates in conjunction with the Power Quicc II series.
These devices come with a switching regulator, which provides the direct supply for the microprocessor's core voltage, and a low-drop-out (LDO) control circuit, which provides the microprocessor's I/O and bus voltage. The switching regulator is a synchronous buck regulator with 50-ohm n-channel MOSFETs. This regulator's bootstrap technique to provides voltage. When the regulator is supplied only from low-input voltage, such as a single +3.3-volt supply, a bootstrap capacitor is charged from the internal boost regulator output through an external diode.
When an overcurrent condition is detected, the buck regulator control circuit shuts the switcher off and the switcher retimer starts to time out. The LDO is adjustable and is capable of supplying a 1-amp output current. The regulator is equipped with a current limit with retry capability. When the voltage measured across the current-sense resistor reaches a 100-millivolt threshold, the control circuit shuts the regulator off. At the same time, a retry timer with a 1 percent duty cycle is engaged, powering up the LDO for 1 ms and checking for overcurrent condition repeatability.
The output of the linear regulator can be adjusted using a feedback control pin. Outputs can be adjusted from 0.8 to 5 V, said Dan Leih, analog products marketing manager at Motorola Semiconductor Products Sector.
In addition to offering the LDO and switching regulators, the PC33701 and PC33702 are equipped with a power-sequencing capability. When an input voltage is applied, the power-sequencing capability allows the output of both regulators to follow the supply rail voltage during power up and power down. Thus, the devices can stay within the 0.4-V sequencing specification defined by the Power Quicc process family.
Two power-sequencing modes are provided: standard and inverted. In standard mode, the power supply chip's switcher output provides the core voltage to the microprocessor. In inverted mode, the LDO regulator provides the microprocessor's core voltage.
The 1.5-A PC33701 and 3-A PC-33702 operate from a 2.8- to 6-V supply and are provided in a 32-pin small-outline IC package. In 10,000-unit quantities, the 701 is offered at $3.26 and the 702 at $4.54. Sampling for the 701 and 702 starts this month.
Motorola is also working on an 8-A power supply chip, the PC33703, optimized for the Power Quicc III family. This chip will start sampling to early customers in October and will be priced at $6.39 in 10,000-unit quantities.
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