EVAL5987 STMicroelectronics, EVAL5987 Datasheet - Page 8

• Manufacturer Part Number: EVAL5987
• Description: BOARD EVALUATION FOR L5987
• Manufacturer: STMicroelectronics
• Type: DC/DC Switching Converters, Regulators & Controllersr

Specifications of EVAL5987

• Main Purpose: DC/DC, Step Down
• Outputs And Type: 1, Non-Isolated
• Voltage - Output: 1.8V
• Current - Output: 3A
• Voltage - Input: 2.9 ~ 18V
• Regulator Topology: Buck
• Board Type: Fully Populated
• Utilized Ic / Part: L5987
• Input Voltage: 2.9 to 18 V
• Output Voltage: 1.8 V
• Operating Supply Voltage: 2.9 to 18 V
• Product: Power Management Modules
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power - Output: -
• Frequency - Switching: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• For Use With/related Products: L5987
• Other names: 497-8369

Functional description
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Functional description
The L5987 is based on a “voltage mode”, constant frequency control. The output voltage
V
an error signal that, compared to a fixed frequency sawtooth, controls the on and off time of
the power switch.
The main internal blocks are shown in the block diagram in
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Figure 3.
OUT
A fully integrated oscillator that provides sawtooth to modulate the duty cycle and the
synchronization signal. Its switching frequency can be adjusted by an external resistor.
The voltage and frequency feed forward are implemented.
The soft-start circuitry to limit inrush current during the start up phase.
The voltage mode error amplifier
The pulse width modulator and the relative logic circuitry necessary to drive the internal
power switch.
The High-side driver for embedded P-channel power MOSFET switch.
The peak current limit sensing block, to handle over load and short circuit conditions.
A voltage regulator and internal reference. It supplies internal circuitry and provides a
fixed internal reference.
A voltage monitor circuitry (UVLO) that checks the input and internal voltages.
A thermal shutdown block, to prevent thermal run away.
is sensed by the feedback pin (FB) compared to an internal reference (0.6 V) providing
Block diagram
Doc ID 14972 Rev 3
Figure
3. They are:
L5987