STEVAL-PSQ001V1 STMicroelectronics, STEVAL-PSQ001V1 Datasheet - Page 20

• Manufacturer Part Number: STEVAL-PSQ001V1
• Description: BOARD EVAL BASED ON PM6680A
• Manufacturer: STMicroelectronics
• Type: Other Power Managementr

Specifications of STEVAL-PSQ001V1

• Design Resources: STEVAL-PSQ001V1 Gerber Files STEVAL-PSQ001V1 Schematic STEVAL-PSQ001V1 Bill of Material
• Main Purpose: DC/DC, Step Down with LDO
• Outputs And Type: 6, Non-Isolated
• Voltage - Output: 0.9 ~ 2.5 V, 1 ~ 3.3 V, 2x 3.3 V, 2.5 V, 5 V
• Current - Output: 4A, 2A, 800mA, 400mA, 400mA, 150mA
• Voltage - Input: 5 ~ 36V
• Regulator Topology: Buck
• Frequency - Switching: 200kHz, 300kHz
• Board Type: Fully Populated
• Utilized Ic / Part: PM6680A
• Input Voltage: 5 V to 36 V
• Output Voltage: 1 V to 3.3 V
• Product: Power Management Modules
• Silicon Manufacturer: ST Micro
• Silicon Core Number: PM6680A
• Kit Application Type: Power Management
• Application Sub Type: Power Supply
• Kit Contents: Board
• Rohs Compliant: Yes
• 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: PM6680A
• Other names: 497-6425; STEVAL-PSQ001V1

Device description
7.2
20/48
Constant on time architecture
Figure 29
off-time constrain (350 ns typ.) is introduced to allow inductor valley current sensing on
synchronous switch. A minimum on-time (130 ns) is also introduced to assure the start-up
switching sequence.
PM6680A has a one-shot generator for each power section that turns on the high side
MOSFET when the following conditions are satisfied simultaneously: the PWM comparator
is high, the synchronous rectifier current is below the current limit threshold, and the
minimum off-time has timed out.
Once the on-time has timed out, the high side switch is turned off, while the synchronous
switch is turned on according to the anti-cross conduction circuitry management.
When the negative input voltage at the PWM comparator
down replica of the output voltage (see the external R1/R2 divider in
valley limit (determined by internal reference Vr = 0.9 V), the low-side MOSFET is turned off
according to the anti-cross conduction logic once again, and a new cycle begins.
Figure 29. Constant on-time block diagram
In steady state the FB pin voltage is about Vr and the regulated output voltage depends on
the external divider:
Equation 4
shows the simplified block diagram of a constant on time controller. A minimum
OUT
=
Vr
×
⎛
⎝
1
+
R
------ -
R
2
1
⎞
⎠
(Figure
29), which is a scaled-
Figure
29), reaches the
PM6680A