STEVAL-PSQ001V1 STMicroelectronics, STEVAL-PSQ001V1 Datasheet - Page 18

• 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
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Device description
The PM6680A is a dual step-down controller dedicated to provide logic voltages for
industrial automation applications.
It is based on a Constant On Time control architecture. This type of control offers a very fast
load transient response with a minimum external component count. A typical application
circuit is shown in Figure 3.
The PM6680A regulates two adjustable output voltages: OUT1 and OUT2. The switching
frequency of the two sections can be adjusted to 200/300 kHz, 300/400 kHz or 400/500 kHz
respectively. In order to maximize the efficiency at light load condition, a pulse skipping
mode can be selected.
The PM6680A includes also a 5 V linear regulator (LDO5) that can power the switching
drivers. If the output OUT1 regulates 5 V, in order to maximize the efficiency in higher
consumption status, the linear regulator can be turned off and their outputs can be supplied
directly from the switching outputs. The PM6680A provides protection versus overvoltage,
undervoltage and over temperature as well as power good signals for monitoring purposes.
An external 1.237 V reference is available.
Constant on time PWM control
If the SKIP pin is tied to 5 V, the device works in PWM mode. Each power section has an
independent on time control.The PM6680A employees a pseudo-fixed switching frequency,
Constant On Time (COT) controller as core of the switched mode section. Each power
section has an independent COT control.
The COT controller is based on a relatively simple algorithm and uses the ripple voltage due
to the output capacitor's ESR to trigger the fixed on-time one-shot generator. In this way, the
output capacitor's ESR acts as a current sense resistor providing the appropriate ramp
signal to the PWM comparator. On-time one-shot duration is directly proportional to the
output voltage, sensed at the OUT1/OUT2 pins, and inversely proportional to the input
voltage, sensed at the VIN pin, as follows:
Equation 1
This leads to a nearly constant switching frequency, regardless of input and output voltages.
When the output voltage goes lower than the regulated voltage Vreg, the on-time one shot
generator directly drives the high side MOSFET for a fixed on time allowing the inductor
current to increase; after the on time, an off time phase, in which the low side MOSFET is
turned on, follows.
in PWM mode.
Figure 28
shows the inductor current and the output voltage waveforms
T
ON
=
K
⋅
V
--------------
V
OUT
IN
PM6680A