STEVAL-ISA027V1 STMicroelectronics, STEVAL-ISA027V1 Datasheet - Page 15

• Manufacturer Part Number: STEVAL-ISA027V1
• Description: BOARD EVAL 1PH STPDN CONV L6726A
• Manufacturer: STMicroelectronics
• Type: DC/DC Switching Converters, Regulators & Controllersr

Specifications of STEVAL-ISA027V1

• Design Resources: STEVAL-ISA027V1 Gerber Files STEVAL-ISA027V1 Schematic STEVAL-ISA027V1 Bill of Material
• Main Purpose: DC/DC, Step Down
• Outputs And Type: 1, Non-Isolated
• Voltage - Output: 1.25V
• Current - Output: 20A
• Voltage - Input: 5 ~ 12V
• Regulator Topology: Buck
• Frequency - Switching: 270kHz
• Board Type: Fully Populated
• Utilized Ic / Part: L6726A
• Input Voltage: 5 V to 12 V
• Output Voltage: 1.25 V
• Product: Power Management Modules
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power - Output: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• For Use With/related Products: L6726A
• Other names: 497-6259

L6726A
8
8.1
8.2
Application details
Output voltage selection
L6726A is capable to precisely regulate an output voltage as low as 0.8 V. In fact, the device
comes with a fixed 0.8 V internal reference that guarantees the output regulated voltage to
be within ±1% tolerance over line and temperature variations between 0 °C and 70 °C
(excluding output resistor divider tolerance, when present).
Output voltage higher than 0.8 V can be achieved by adding a resistor R
and ground. Referring to
where V
Compensation network
The control loop shown in
transconductance type with fixed gain (3.3 ms typ.). The FB voltage is regulated to the
internal reference, thus the output voltage is fixed accordingly to the output resistor divider
(when present).
Transconductance error amplifier output current generates a voltage across Z
compared to oscillator saw-tooth waveform to provide PWM signal to the driver section.
PWM signal is then transferred to the switching node with V
filtered by the output filter.
Figure 8.
The converter transfer function is the small signal transfer function between the voltage at
the output node of the EA (COMP) and V
conjugate) at frequency F
REF
is 0.8 V.
PWM control loop
ΔV
OSC
OSC
Figure
LC
Figure 8
C
R
depending on the L-C
F
COMPARATOR
F
V
Doc ID 12754 Rev 4
COMP
1, the steady state DC output voltage will be:
OUT
_
+
PWM
is a voltage mode control loop. The error amplifier is a
Z
C
F
=
P
OTA
V
OUT
REF
. This function has a double pole (complex
+
_
⋅
⎛
⎝
V
OUT
1
V
IN
R
REF
FB
+
OS
resonance and a zero at F
---------- -
R
R
L
OS
FB
R
FB
IN
⎞
⎠
amplitude. This waveform is
OUTPUT
DIVIDER
R
C
ESR
OUT
Application details
OS
V
OUT
between FB pin
F
, which is
ESR
15/35