EVALA5972D STMicroelectronics, EVALA5972D Datasheet - Page 7

• Manufacturer Part Number: EVALA5972D
• Description: Power Management Modules & Development Tools EVAL BOARD A5972 Auto Grade
• Manufacturer: STMicroelectronics
• Type: DC/DC Switching Converters, Regulators & Controllersr

Specifications of EVALA5972D

• Input Voltage: 4.4 V to 36 V
• Output Voltage: 1.235 V to 35 V
• Board Size: 23 mm x 20 mm
• Product: Power Management Modules
• Supply Current: 2 A
• Dimensions: 23 mm x 20 mm
• For Use With/related Products: AN1517
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

AN1517
2.3
2.4
Figure 5.
Oscillator
Figure 6
The Clock Generator provides the switching frequency of the device, which is internally fixed
at 250 kHz. The Frequency Shifter block acts to reduce the switching frequency in case of
strong over-current or short-circuit. The clock signal is then used in the internal logic
circuitry and is the input of the Ramp Generator.
The Ramp Generator circuit provides the sawtooth signal, used to for PWM control and the
internal voltage feed-forward.
Figure 6.
Current protection
The L5973AD has two types of current limit protection: pulse-by-pulse and frequency
foldback.
The schematic of the current limitation circuitry for the pulse-by-pulse protection is shown in
Figure
The smallest one includes a resistor in series, R
R
switched off until the next falling edge of the internal clock pulse.
SENSE
7. The output power PDMOS transistor is split into two parallel PDMOS transistors.
and if it reaches the threshold, the mirror becomes unbalanced and the PDMOS is
shows the block diagram of the oscillator circuit.
Internal regulator circuit
Oscillator circuit block diagram
STARTER
V
CC
Ibias_osc
FREQUENCY
GENERATOR
FREQUENCY
GENERATOR
SHIFTER
SHIFTER
CLOCK
CLOCK
IC BIAS
SYNCHRONIZATOR
SYNCHRONIZER
SENSE
GENERATOR
GENERATOR
RAMP
RAMP
. The current is sensed through
PREREGULATOR
AM00006v1
BANDGAP
CLOCK
RAMP
SYNC
VREG
t
VREF
AM00007v1
Functional description
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