描述 L5964 is a dual step-down switching regulator with internal power switches and a low drop-out linear/standby regulator, designed for car battery supplied applications. All the regulators have independent supply voltages, enables pins, power goods and thermal protections. The switching regulators have selectable voltage supervisors and power goods, and selectable current limits. The LDO has power good and fixed current limitation.
The PMIC finds application in different automotive systems, where load dump protection and wide input voltage range are mandatory.
Typically, the regulator connected to the battery works at low frequency, while the one connected to the pre-regulated voltage can make the most of the high frequency operation. In this way the efficiency of the system is improved and the ability of the product to function both as a pre- and post-regulator is exploited.
For the same reason, in applications where both regulators must be connected to a battery, for example when powering a hub consisting of two USB ports, it is recommended to work at the lowest frequency. The linear regulator that remains available can be used to power the controller.
The two DC-DC converters can work in free-run condition, with frequency selectable between two values, 270 kHz or 2.2 MHz, or synchronize themselves to an external clock (SYNCIN pin). They are 180° out of phase, while the synchronization output signal (SYNCOUT pin) is 90° out of phase with the first regulator. The phase shift simplifies the use of two ICs in the same application (4 DC/DCs regulators).
The high operating frequency allowed by the synchronization input helps to reduce AM and FM interferences and grants the use of small and low cost inductors and capacitors.
The two switching regulators can be used in parallel and increase the output current capability up to 7 A.
The L5964 can work in two different modes, normal and microcontroller mode, based on the condition of a hardware pin.
When the microcontroller mode is selected, some pins change functionality. For example, the reset and watchdog functions are available. In this way the PMIC easily manages the power management of a microcontroller.
The availability of power good and enable signals, however, makes easy to manage the system power up sequence even without the presence of a microcontroller, since it is possible to enable a voltage only when the previous voltage is stable and with a precise delay.
The total quiescent current, when both DC/DCs and LDO are disabled, is less than 10 μA.
The product is available in LQFP64 with exposed pad up. This package is able to dissipate power through an external heatsink.