Texas Instruments C2000 Piccolo LaunchPad Installation guide

C2000 Digital Power Supply
Workshop
Texas Instruments
Technical Training
Copyright © 2008 Texas Instruments. All rights reserved.
D SP
TEXAS INSTRUMENTS
TECHNOLOGY

Introduction to Digital Power Supply Design
What is a Digital Power Supply?
Why use Digital Control
Techniques?
Peripherals used for Digital Power
Supply Design
Development Tools and Software

What is Digital Power?
Generic Power System Block Diagram
The controller block is what differentiates between a digital
power system and a conventional analog power system
Switches
(FETs)
LC
Network
Controller
(Compensator)
Vout
PWM
Vin

Why Digital Control Techniques?
Controller
Analog
or
Digital ??
PWM
Sensor(s)
Bandwidth limitations (sampling loop)
PWM frequency and resolution limits
Numerical problems (quantization, rounding,…)
AD / DA boundary (resolution, speed, cost)
CPU performance limitations
Bias supplies, interface requirements
Component drift and aging / unstable
Component tolerances
Hardwired / not flexible
Limited to classical control theory only
Large parts count for complex systems
Insensitive to environment (temp, drift,…)
High reliability
S/w programmable / flexible solution
Precise / predictable behavior
Advanced control possible (non-linear, multi-variable)
Can perform multiple loops and “other” functions
High bandwidth
High resolution
Easy to understand / use
Historically lower cost
+
Digital ControllerAnalog Controller
Power Elec.

Benefits of Digital Control
Eliminate Components
PFC
Filter
Bridge V
VDC/DC
Aux P/S
Output
Multiple chips for
control
Micro-controller for
supervisory
Dedicated design
Traditional Analog
Power Supply
VPFC
Filter
Bridge V
V
Aux P/S
V
DC/DC
Converter
Control
Multi-mode
Power control
MCU Supervisory
ousekeeping
Circuits
Current/Load
Sharing
Control
DC/DC V
To ost
PFC Control
Interface
Circuit
Monitor
(MCU?)
Inrush/
ot-plug
Control
IIIIOutput
PFC Control
Interface
Circuit
Monitor
(MCU)
Inrush/
ot-plug
Control
DC/DC
Converter
Control
Multi-mode
Power control
MCU Supervisory
ousekeeping
Circuits
Current/Load
Sharing
Control
Reduce Manufacturing Cost
Variable DC Output
Better Performance Across Corners
Failure Prediction
One Device, Multiple DC Outputs
One Design, Multiple Supplies
Digital controller enables multi-threaded applications
84
51

Analog Control System








+
+
=sCR
sCR
R
R
sC
22
11
1
2
1
1
)(
)()(
)()()(
01
2
2
2
3
3
tftyk
dt
tdy
k
dt
tyd
k
dt
tyd =+++
Differential equations
1st , 2nd , 3rd ,…order
eed to find:
R1, R2, C1, C2
Laplace Transform
“Analog Computation”
Differential equations

Digital Control System
)()1()2(
)1()2()(
012
12
nEbnEbnEb
nUanUanU
⋅+−⋅+−⋅
+
−
⋅
+
−
⋅
=
)()()( nWnRnEwhere
−
=
Κ
)()(
)()()(
01
2
2
2
3
3
tftyk
dt
tdy
k
dt
tyd
k
dt
tyd =+++
Differential equations
1st , 2nd , 3rd ,…order
Difference equation
eed to find:
a1, a2, b0, b1, b2
Laplace Transform
Z Transform
OR

Time Sampled Systems

Processor Bandwidth
Sample Freq (=PWM) Sample Period
(kHz) (ns)
100 10000
300 3333
500 2000
700 1429
1000 1000
1500 667
2000 500

Time Division Multiplexing (TDM)
Control Code (C2)
Processor 2 ControlControl Code
y(n)
x(n)
Control Code (C1)
Processor 1 ControlControl Code
Control Code (C3)
Processor 3 ControlControl Code
Single CPU C1 C2 C3 C1 C2 C3 C1 C2 C3
TSAMPLE