EVALA5970AD STMicroelectronics, EVALA5970AD Datasheet - Page 11

• Manufacturer Part Number: EVALA5970AD
• Description: BOARD EVAL FOR A5970AD REG
• Manufacturer: STMicroelectronics

Specifications of EVALA5970AD

• Main Purpose: DC/DC, Step Down
• Outputs And Type: 1, Non-Isolated
• Voltage - Output: 1.235 ~ 35V
• Current - Output: 1A
• Voltage - Input: 4 ~ 36V
• Regulator Topology: Buck
• Frequency - Switching: 500kHz
• Board Type: Fully Populated
• Utilized Ic / Part: A5970AD
• Product: Power Management Modules
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power - Output: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

A5970AD
5.4
Figure 5.
Figure 6.
Current protection
The A5970AD features 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. Due to this reduction of the
ON time, the output voltage decreases. Since the minimum switch ON time necessary to
sense the current in order to avoid a false overcurrent signal is too short to obtain a
sufficiently low duty cycle at 500 kHz (see
overcurrent or short circuit conditions could be not properly limited. For this reason the
switching frequency is also reduced, thus keeping the inductor current under its maximum
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
A5970AD
A5970AD
A5973D
A5973D
A5973D
A5973D
A5973D
A5973D
Oscillator circuit block diagram
Synchronization example
SS/INH
SS/INH
SS/INH
SYNCH
SYNCH
SYNCH
SS/INH
SS/INH
SS/INH
SYNCH
SYNCH
SYNCH
GND
GND
GND
GND
GND
GND
OUT
OUT
OUT
OUT
OUT
OUT
FB
FB
FB
FB
FB
FB
COMP
COMP
COMP
COMP
COMP
COMP
Doc ID 14661 Rev 4
Chapter
SENSE
8.4), the output current in strong
. The current is sensed through
A5970AD
A5970AD
A5973D
A5973D
A5973D
A5973D
A5973D
A5973D
SS/INH
SS/INH
SS/INH
SS/INH
SS/INH
SS/INH
SYNCH
SYNCH
SYNCH
SYNCH
SYNCH
SYNCH
Functional description
GND
GND
GND
GND
GND
GND
OUT
OUT
OUT
OUT
OUT
OUT
FB
FB
FB
FB
FB
FB
COMP
COMP
COMP
COMP
COMP
COMP
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