AN3302 Datasheet, PDF (1/13 Pages) STMicroelectronics – Monolithic power management for high definition ODD with

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
DSP
DRAM
Flash
Motors
Reset
1.2 V
3.3 V
5V
Reset IC
Step Down
ADJ 700 mA
Step Down
3.3 V 700 mA
Motor
Control IC
BLUE Laser Driver
6 to 12 V
Step Up
ADJ 800mA
5V
5V
STODD01
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