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Automotive Monolithic dual 3.5A step-down switching regulator with LDO

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Product overview


L5964 is a dual step-down switching regulator with internal power switches and a low drop-out linear/standby regulator. All the regulators have independent supply voltages, enables, 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 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).

DC-DC1 and DC-DC2 current limits can be independently set through the pins OCPSET1 and OCPSET2 respectively. Two current limits are available, 2 A (1.7 A min) and 3.5 A (3.7 A min). For operation > 2 A, 20 V, with less than 0.5 V forward voltage and 2 A at room temperature, Schottky diodes placed as close to the PHASE1/2 pins as possible, to ground are required.

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 L5964 can manage the microcontroller supply. A configurable reset output and a configurable watchdog input are available.

This IC finds application in the automotive segment, where load dump protection and wide input voltage range are mandatory. L5964 has been qualified for car passenger cars, with a standard 14 V battery. The total quiescent current, when both DC/DCs and LDO are disabled, is less than 10 µA.

The product is available in LQFP64 exposed pad up package. The slug, whenever possible, has to be connected to the ground plane.

  • All features

    • AEC-Q100 qualified
    • Two step-down synchronous switching voltage regulators with internal power switches:
      • Output voltage selectable by external divider (feedback voltage at 0.9 V)
      • Minimum and maximum output is limited by minimum and maximum duty cycle
      • Internal high-side/ low-side NDMOS
      • 270 kHz and 2.2 MHz selectable free-run frequencies
      • 125 kHz < f < 2.3 MHz synchronization range at SYNCIN pin
      • Programmable current limits at 2 A and 3.5A (> 2 A requires the addition of external schottky diodes)
      • Independent hardware enabling pins
      • Independent supply inputs
      • 180° phase shift between outputs
      • Synch out 90° phase shift vs DC-DC1
      • Programmable switching frequency divider by 1, 2, 4, 8 between the two regulators
      • The two buck converters can be connected in parallel (for evaluation purposes only)
    • Independent voltage supervisors/power-goods with selectable thresholds through external pin:
      • two available thresholds for UV/OV/PG signals: 90-120-95% or 80-110-85% (output voltage percentage)
    • Soft-start, thermal protection
    • One standby/linear regulator:
      • Output selectable with external resistor divider till 10 V
      • Soft start, hardware enable pin
      • 250 mA maximum current capability
      • Standby operative mode
      • Programmable power good thresholds (85% or 95% output voltage percentage)
      • Thermal protection
    • Microcontroller reset with programmable duration, activated by output under voltage or watchdog fault
    • External High Side Driver enable pin
    • One integrated window watchdog (5 ms ≤ window ≤ 50 ms, with ± 20% tolerance)
    • Short circuit protected outputs
    • Low external components number
    • Thermal shutdown junction temperature 150°C

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STMicroelectronics - L5964

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LQFP Automotive Ecopack2




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