Integrated Power Regulation...
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Integrated Power Regulation Solutions Instructor: Fionn Sheerin, Senior Product Marketing Engineer, Microchip Technology, Inc.
Transcript of Integrated Power Regulation...
Integrated PowerRegulation Solutions
Instructor:Fionn Sheerin,
Senior Product Marketing Engineer, Microchip Technology, Inc.
HOUSEKEEPING• Housekeeping• Presentation• Text Chat Questions and Answers• Wrap-up
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Agenda
Introduction to DC-DC converters
Linear regulators
Charge pump regulators
Integrated switching regulators (buck and boost)
Guidelines for implementation
What to use when
Passive component selection
Board layout
Track 2: Analog and Hybrid Analog/Digital
System Control
Track 3: Digital System Control
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Linear Regulators
Reduce the input voltage to a lower, constant
output voltage using a variable resistor
+
-
Input Output
Bandgap
Reference
Requirements:
Capacitance
Benefits:
No switching, low noise
Low losses at light loads
Drawbacks:
Large voltage differences
or large current changes
suffer large losses
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Charge Pumps
Increase or decrease the input using a
switching capacitor
Requirements:
Capacitance
Benefits:
Simple
Inductorless
Low losses at light
loads
Drawbacks:
Limited current output
Vin
Vout+
-
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Charge Pumps
Phase 1: the capacitor is charged to Vin
while Vout is floating
Requirements:
Capacitance
Benefits:
Simple
Inductorless
Low losses at light
loads
Drawbacks:
Limited current output
Vin
Vout+
-
VC = Vin
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Charge Pumps
Phase 2: the capacitor is added to Vin
and connected to Vout
Requirements:
Capacitance
Benefits:
Simple
Inductorless
Low losses at light
loads
Drawbacks:
Limited current output
Vin
Vout+
-
VC = Vin
VOUT = VC + Vin
= 2 * Vin
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Charge Pumps
This commonly requires at least one
external capacitor
Requirements:
Capacitance
Benefits:
Simple
Inductorless
Low losses at light
loads
Drawbacks:
Limited current output
Vin
Vout+
-
Integrated Charge
Pump
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Buck Regulators
Decrease the input voltage by
averaging it with ground based
on a variable duty cycle
Requirements:
Capacitance and
Inductance
Benefits:
Low losses at
high loads
Drawbacks:
Switching noise
High component
count
Vin
Vout
+
-
Control
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Buck Regulators
Phase 1: the inductor is
charged from the input to
output
Requirements:
Capacitance and
Inductance
Benefits:
Low losses at
high loads
Drawbacks:
Switching noise
High component
count
Vin
Vout
+
-
Control
Current flow
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Current flow
Buck Regulators
Phase 2: the inductor continues
to draw current from ground,
maintaining the output
Requirements:
Capacitance and
Inductance
Benefits:
Low losses at
high loads
Drawbacks:
Switching noise
High component
count
Vin
Vout
+
-
Control
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Buck Regulators
Buck regulators commonly
require input, output capacitors
and an inductor
Requirements:
Capacitance and
Inductance
Benefits:
Low losses at
high loads
Drawbacks:
Switching noise
High component
count
Vin
Vout
+
-
Control
Integrated Buck
Converter
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Boost Regulators
Increase the input voltage
using inductive voltage
spiking
Requirements:
Capacitance and
Inductance
Benefits:
Low losses at high
loads
Drawbacks:
Switching noise
High component
count
Vin
Vout
+
-
Control
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Boost Regulators
Phase 1: the inductor is
charged using current
flowing from input to gnd
Requirements:
Capacitance and
Inductance
Benefits:
Low losses at high
loads
Drawbacks:
Switching noise
High component
count
Vin
Vout
+
-
Control
Current flow
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Boost Regulators
Phase 2: the inductor
forces that energy through
to the output
Requirements:
Capacitance and
Inductance
Benefits:
Low losses at high
loads
Drawbacks:
Switching noise
High component
count
Vin
Vout
+
-
Control
Current flow
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Boost Regulators
Boost regulators need input,
output capacitors and an
inductor
Requirements:
Capacitance and
Inductance
Benefits:
Low losses at high
loads
Drawbacks:
Switching noise
High component
count
Vin
Vout
+
-
Control
Integrated Boost
Converter
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What to Use When
There is no perfect DC-DC solution
Voltage
Increase
(step-up,
boost)
Voltage
Decrease
(step-down,
buck)
Relative output power
Charge
Pumps
Linear
Regulators
Integrated
Boost
Regulators
Integrated
Buck
Regulators
Analog Control
Boost
Regulators
Analog Control
Buck
Regulators
Digital Control
Boost
Regulators
Digital Control
Buck
Regulators
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Passive Component Selection
Passive components make a dramatic
difference in DC-DC performance
With a linear regulator:
The capacitor acts like part of an R-C filter, reducing
voltage changes during transient events
With a switching regulator:
The inductor and capacitor work together similar to an
L-C filter; it trades steady state ripple against transient
response
In all cases, the passive components must
keep the system stable. Stability
requirements are addressed in the datasheet.
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Linear RegulatorCapacitance Selection
Start with the datasheet recommendations
for input and output capacitors
Example: Output capacitance discussion from MCP1703A datasheet
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Linear RegulatorCapacitance Selection
Start with the datasheet recommendations
for input and output capacitors
Example: Output capacitance discussion from MCP1703A datasheet
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Linear RegulatorCapacitance Selection
Start with the datasheet recommendations
for input and output capacitors
Be sure to test the stability for the system for
worst case line and load steps, at most
extreme temperatures
Smaller
Capacitance
Larger
Capacitance
SlowerTransient
ResponseFaster
Smaller Size and Cost Larger
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Switching RegulatorInductor Selection
Start with the datasheet recommended range
It is always desirable to reduce the effective
resistance (higher Q), but that often requires
more expensive inductors
Smaller
Inductance
Larger
Inductance
FasterTransient
ResponseSlower
Higher Ripple Current Lower
Lower Series Resistance Higher
Smaller Size and Cost Larger
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Switching RegulatorCapacitor Selection
Start with the datasheet recommended range
It is always desirable to minimize the ESR,
which will improve transient response,
reduce losses, and improve stability
Smaller
Capacitance
Larger
Capacitance
SlowerTransient
ResponseFaster
Higher Ripple Current Lower
Higher Series Resistance Lower
Smaller Size and Cost Larger
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Layout Guidelines
Why is it important
to have good
layout?
• Optimizes efficiency
• Alleviates Thermal
Stress
• Minimizes noise and
interactions among
traces and
components
• Reduces EMI
Example: MCP16301 buck regulator ripple
and noise at constant 500 mA load
High frequency noise is always a layout issue!
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Layout Guidelines
Things to consider when creating the PCB:
Careful grounding
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Layout Guidelines
Things to consider when creating the PCB:
Minimize areas and lengths of loops with high frequency switching
current
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Layout Guidelines
Things to consider when creating the PCB:
Place filter capacitors close to the IC or the traces that carry the
main current
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Layout Guidelines
Things to consider when creating the PCB:
Keep the feedback and control traces away from the power traces
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Layout Guidelines
Things to consider when
creating the PCB:
Chose the width of the
traces based on
acceptable temperature
rises at the rated current,
as well as acceptable DC
and AC impedances
Use the PCB as a heat sink
Recommended Track Width For
1oz copper PCB, 10 °C above TA
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Layout Guidelines
Things to consider when placing
components
Place input and output
capacitors as close as possible
to the DC-DC converter IC
INPUT
OUTPUT
Power GND
Analog GND
Via for Enable
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Layout Guidelines
Things to consider when placing
components
Place input and output
capacitors as close as possible
to the DC-DC converter IC
INPUT
OUTPUT
Power GND
Analog GND
Via for Enable
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Layout Guidelines
Things to consider when placing
components:
Place the inductor to minimize
the switch node
INPUT
OUTPUT
Power GND
Analog GND
Via for Enable
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Layout Guidelines
Things to consider when placing
components:
Place the inductor to minimize
the switch node
INPUT
OUTPUT
Power GND
Analog GND
Via for Enable
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Layout Guidelines
Things to consider when placing
components:
Place feedback resistors away
from the inductor and
switching traces
INPUT
OUTPUT
Power GND
Analog GND
Via for Enable
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Layout Guidelines
Things to consider when placing
components:
Place feedback resistors away
from the inductor and
switching traces
INPUT
OUTPUT
Power GND
Analog GND
Via for Enable
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Layout Guidelines
Things to consider when placing
components:
Use short, wide power traces
on top, with large bottom
ground plane
INPUT
OUTPUT
Power GND
Analog GND
Via for Enable
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Layout Guidelines
Things to consider when placing
components:
Use short, wide power traces
on top, with large bottom
ground plane
INPUT
OUTPUT
Power GND
Analog GND
Via for Enable
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Summary
Lower power DC-DC conversion can be
easily accomplished with integrated DC-DC
regulators
Good regulator selection, passive
component selection, and layout are required
Higher power systems often require discrete
analog or digital power implementations,
which means stabilizing the control loop
Track 2: Analog and Hybrid Digital/Analog Power
Control Implementations
Track 3: Digital Power Control
Audience Q & Avia Chat
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Instructor: Fionn Sheerin, Microchip Technology, Inc.
Moderator:Rich NassEVP, OpenSystems Media
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