AN3302
Application note
Monolithic power management for high definition ODD with
true shutdown, reset, and programmable step-up voltage
Introduction
Blu-ray disc players have grown rapidly in popularity due to the increasing availability of
digital services and high definition digital media content.
This application note describes how to use STODDO1, a complete power management for
BIu-ray disc players, based on high density optical storage devices. It integrates two step-
down converters and one step-up.
The step-down converters are optimized for powering Iow-voltage digital core, up to 0.8 A, in
ODD applications and, generally, to replace a high current linear solution when the power
dissipation may cause an overheating of the application environment.
The step-up provides the needed voltage for supplying the blue laser in mobile applications
where only 5 V is available. The output voltage is programmable, by using S-wire protocol, in
the range of 6.5 V to 14 V, with a current capability of 0.7 A.
Figure 1.
Blu-ray disc player power management architecture based on STODD01
BLUE Laser Driver
6 to 12 V
Reset
Reset IC
Step Down
ADJ 700 mA
Step Up
ADJ 800mA
DSP
1.2 V
5V
DRAM
Flash
3.3 V
Step Down
3.3 V 700 mA
5V
STODD01
5V
Motors
Motor
Control IC
AM07854v1
The integrated low R
DSon
, for N-channel and P-channel MOSFET switches, contributes to
obtaining high efficiency.
The enable function for the step-up section, and reset function for monitoring the input
voltage, make the device particularly suitable for optical storage applications.
The high switching frequency (1.2 MHz typ.) allows the use of tiny surface-mounted
components. Furthermore, a low output ripple is guaranteed by the current mode PWM
topology and by the use of X7R or X5R and low ESR SMD ceramic capacitors.
The device includes soft-start control, thermal shutdown, and peak current limit, to prevent
damage due to accidental overload.
January 2011
Doc ID 18163 Rev 1
1/13
www.st.com
ATA Connector with
Power
Contents
AN3302
Contents
1
2
Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Recommended PCB Iayout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1
2.2
Layout considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Programming the output voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3
Test results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.1
3.2
3.3
S-wire protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Inductor selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Input and output capacitor selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
4
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2/13
Doc ID 18163 Rev 1
AN3302
Block diagram
1
Figure 2.
Block diagram
Block diagram and reference circuit
C1
L1
V
IN
STODD01
V
IN_A
C3
SW1
Out1
FB1
R1
C4
R2
V
OUT1
6.5V-14V
Step Up
EN
S-Wire
SW2
FB2
Step Down
L2
V
OUT2
C5
3.3V
TX
V
IN_P
SW3
C2
R5
Reset
FB3
L3
R3
V
OUT3
0.8V-0.94*Vin
Reset
Step Down
GND
GND
R4
Reset
GND
GND
C6
AM07856v1
Table 1.
List of external components
(1)
Manufacturer
Part number
Value
Size
Component
C1, C2, C3
C4, C5, C6
L1
L2, L3
R1
R2
R3
R4
R5
Murata
Murata
Coilcraft
Coilcraft
GRM21BR61A1O6KE19L
GRM32ER61C226KE2OL
LPS6225-472MLB
LPS4O18-332MLB
33 k
Ω
(V
OUT1
= 8.8 V)
3.3 k
Ω
27 k
Ω
(V
OUT3
= 1.2 V)
47 k
Ω
100 k
Ω
10 µF
22 µF
4.7 µH
3.3 µH
(2)
0805
1210
6 x 6 x 2.5
4.1 x 4.1 x 1.8
0603
0603
(3)
0603
0603
(4)
0603
If the S-wire function Is not used, the TX pin must be connected to GND.
List of external components
(1)
1. Components listed above refer to a typical application. Operation of the STODD01 is not limited to the choice of these
external components.
2. R
1
and R
2
are calculated according to the following formula: R
1
= R
2
(V
OUT1
/ V
FB1
-1)
It is recommended to use resistors with values in the range of 1 kΩ to 50 kΩ.
3. R
3
and R
4
are calculated according to the following formula: R
3
= R
4
(V
OUT3
/ V
FB3
-1)
It is recommended to use resistors with values in the range of 1 kΩ to 50 kΩ.
4. It is recommended to use resistors with values in the range of 100 kΩ to 1 MΩ.
Doc ID 18163 Rev 1
3/13
Recommended PCB Iayout
AN3302
2
Figure 3.
Recommended PCB Iayout
Recommended PCB layout
AM07857v1
2.1
Layout considerations
The layout is an important design step for all switching power supplies due to the high
switching frequency and peak current. If the layout is not performed carefully, important
parameters such as efficiency and output voltage ripple may be out of specification.
Short, wide traces must be implemented for the main current and for power ground paths.
The input capacitor must be placed as close as possible to the IO pins as well as the
inductor and output capacitor.
The feedback pin (FB) connection to the external resistor divider is a high impedance node,
so interference can be minimized by placing the routing of the feedback node as far as
possible from the high current paths. To reduce pick-up noise, the resistor divider must be
placed very close to the device.
A common ground node minimizes ground noise. The exposed pad of the package must be
connected to the common ground node.
4/13
Doc ID 18163 Rev 1
AN3302
Recommended PCB Iayout
2.2
Programming the output voltage
The output voltage for the step-up (ch1) can be adjusted from 6.5 V up to 14 V by
connecting a resistor divider between the V
OUT1
and GND, the middle point of the divider
must be connected to the FB1 pin, as shown in
Figure 2
.
The resistor divider should be chosen according to the following equation:
Equation 1
⎞
⎛
R
V
OUT1
=
V
FB1
⋅ ⎜
1
+
1
⎟
⎟
⎜
R
⎠
⎝
2
where V
FB1
is programmable, by using S-wire protocol, in the range of 0.8 V to 1.25 V (see
Figure 11
).
It is recommended to use a resistor with a value in the range of 1 k
Ω
to 50 k
Ω
. Lower values
may also be suitable, but increase current consumption.
For ch2 the device integrates the resistor divider needed to set the correct output voltage
(3.3 V). This allows to save 2 external components. The FB2 pin must be connected directly
to V
OUT2
.
The output voltage for ch3 can be adjusted from 0.8 V up to 94 % of the input voltage value
by connecting a resistor divider between the V
OUT3
and GND, the middle point of the divider
must be connected to the FB3 pin, as shown in
Figure 2
.
The resistor divider should be chosen according to the following equation:
Equation 2
⎛
R
⎞
V
OUT 3
=
V
FB3
⋅ ⎜
3
+
1
⎟
⎜
R
⎟
⎝
4
⎠
It is recommended to use a resistor with a value in the range of 1 k
Ω
to 50 k
Ω
. Lower values
may also be suitable, but increase current consumption.
Doc ID 18163 Rev 1
5/13
TI技术论坛
京公网安备 11010802033920号
Copyright © 2005-2026 EEWORLD.com.cn, Inc. All rights reserved
电子工程世界
