EVALA5970D STMicroelectronics, EVALA5970D Datasheet - Page 7

• Manufacturer Part Number: EVALA5970D
• Description: Power Management Modules & Development Tools EVAL BOARD A5970D Auto Grade
• Manufacturer: STMicroelectronics
• Type: DC/DC Switching Converters, Regulators & Controllersr

Specifications of EVALA5970D

• 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: 1 A
• Dimensions: 23 mm x 20 mm
• For Use With/related Products: AN1330
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

AN1330
2.3
Figure 5.
Oscillator and synchronizer
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 overcurrent or short circuit. The clock signal is then used in the internal logic circuitry
and is the input of the Ramp Generator and synchronizer blocks.
The Ramp Generator circuit provides the sawtooth signal, used for PWM control and the
internal voltage feed-forward, while the synchronization circuit generates the
synchronization signal. The device also has a synchronization pin which can works both as
Master and Slave.
As Master, it serves to synchronize external devices to the internal switching frequency, and
as Slave to synchronize itself using an external signal up to 500 kHz.
In particular, when connecting together two devices the one with the lower switching
frequency works as Slave and the other as Master.
To synchronize the device, the SYNC pin must pass from a low level to a level higher than
the synchronization threshold with a duty cycle that can vary from approximately 10% to
90%, depending also on the signal frequency and amplitude.
The frequency of the synchronization signal must be, at a minimum, higher than the internal
switching frequency of the device (250 kHz).
shows the block diagram of the oscillator circuit.
Internal regulator circuit
STARTER
V
CC
IC BIAS
PREREGULATOR
AM00006v1
BANDGAP
VREG
VREF
Functional description
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