STEVAL-ISA052V2 STMicroelectronics, STEVAL-ISA052V2 Datasheet - Page 19

• Manufacturer Part Number: STEVAL-ISA052V2
• Description: BOARD EVAL BASED ON PM6675A
• Manufacturer: STMicroelectronics
• Type: DC/DC Switching Converters, Regulators & Controllersr

Specifications of STEVAL-ISA052V2

• Design Resources: STEVAL-ISA052V2 Gerber Files STEVAL-ISA052V2 Schematic STEVAL-ISA052V2 Bill of Material
• Main Purpose: DC/DC, Step Down with LDO
• Outputs And Type: 2, Non-Isolated
• Voltage - Output: 1.5V, 0.6 ~ 3.3V
• Voltage - Input: 4.5 ~ 36 V
• Regulator Topology: Buck
• Board Type: Fully Populated
• Utilized Ic / Part: PM6675AS
• Input Voltage: 4.5 V to 36 V
• Output Voltage: 1.5 V
• Product: Power Management Modules
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Output: -
• Power - Output: -
• Frequency - Switching: -
• Lead Free Status / Rohs Status: Supplier Unconfirmed
• For Use With/related Products: PM6675AS
• Other names: 497-8413

PM6675AS
7.1.2
Figure 24. Switching section simplified block diagram
Output ripple compensation and loop stability
The loop is closed connecting the center tap of the output divider (internally, when the fixed
output voltage is chosen, or externally, using the VSEL pin in the adjustable output voltage
mode). The feedback node is the negative input of the error comparator, while the positive
input is internally connected to the reference voltage (Vr = 0.6 V). When the feedback
voltage becomes lower than the reference voltage, the PWM comparator goes high and sets
the control logic, turning on the high-side MOSFET. After the On-Time (calculated as
previously described) the system releases the high-side MOSFET and turns-on the
synchronous rectifier.
The voltage drop along ground and supply PCB paths, used to connect the output capacitor
to the load, is a source of DC error. Further the system regulates the output voltage valley,
not the average, as shown in
an additional source of DC error. To compensate this error, an integrative network is
introduced in the control loop, by connecting the output voltage to the COMP pin through a
capacitor (CINT) as shown in
C
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Figure 22
m
VSEL<4V
Figure 25
m
p
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P
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-
-
. Thus, the voltage ripple on the output capacitor is
S
S
.
K
K
V
V
1-Shot generator
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N
D
D
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+
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-
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C
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Anti cross-
conduction
circuitry
2.5V
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500mV
V
V
2.5V
V
V
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B
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F
F
Device description
b
b
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L
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H
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d
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19/48
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