Mobile Storage
SM3251
‑ USB Flash Drive Controllers
Key Features
Dyna Family
Cmplete USB2.0 compatibility
Complies with USB Mass Storage Class specification
version 1.0
Bulk Only transport protocol
Complies with USB power specifications for bus-powered
devices
Operating systems supported:
- Windowss
®
Vista and Windowss
®
XP/2000/Me/98/98SE
- Mac OS 9.X/X and above
- Linux Kernel 2.4 and above
In System Programming (ISP) firmware update capability
Supports single channels for Flash memory
Compatible with SLC or MLC NAND-type Flash
and up to 4 banks
Supports 8- and 15-bit ECC hardware engines for highly
error correction
Supports Windows® Vista Ready Boost function
Supports VID, PID, serial number, and vendor
information updates
An LED indicates when the USB Flash drive is in
Ready/Working mode
Supports a “Write Protection” security function to
protect data
Integrated 80C51 compatible 8-bit microprocessor with
enhanced features
12MHz crystal driver circuit
1.8 volts low power core operation
Operates on a single power supply (Vdd = 5.0V or 3.3V)
USB2.0 Single-Channel Flash Controller
Overview
The SM3251 is a USB Flash drive controller that combines
high compatibility and performance to support single-
channel SLC and MLC NAND-type Flash memory in
one chip. Based on 0.162μm fabrication technology and
low-power consumption considerations, the SM3251
complies with USB2.0 power specifications for bus-
powered devices. In conjunction with USB2.0 Flash drive
applications, the SM3251 supports high capacity (up to
4 data Flash banks), “write protection” functionality, PC
boot-up from a USB2.0 Flash drive, password protection,
and secured partitioning functions.
The SM3251 controller delivers an extremely reliable,
high data transfer rate through an 8/15-bit ECC engine
to reduce MLC Flash read/write disturbance errors.
Combining a 5-3.3V regulator and power-on-rest feature,
the SM3251 maximizes efficiency and reduces overall
costs. The SM3251 is available in 48-pin QFP, and 48-
pin QFN packages with a manufacturing-ready turnkey
solution.
Applications
Target Performance (high‑speed)
Package
USB Flash Drive
USB Solid State Disk
Embedded Application
High-Speed NAND Storage
SLC sustained read rate: 25 MB/s*
SLC sustained write rate: 22 MB/s*
MLC sustained read rate: 22 MB/s*
48-pin QFP, 44-pin LGA and
48-pin QFN packages available
0.162um IC
(integrated circuit)
MLC sustained write rate: 12 MB/s*
*Figures may vary between test platforms.
SM3251 Block Diagram
NAND Flash 1
NAND Type
Flash Memory
NAND Flash 2
NAND Flash 3
NAND Flash 4
USB
Host
Device
RAM Buffer
USB 2.0 HS/FS
Endpoint Controller
External BUS I/F
(DMA Data Transfer)
RAM Buffer
12MHz
Clock PLL
& Oscillator
Data RAM
uP8051 Core
Mask ROM
Program RAM
ECC Engine
(8/15 Bits)
Voltage Regulator
(3.3V to 1.8V)
Voltage Regulator
(5V to 3.3V)
5V Power
Write Protect Switch,
Status Indicator LED,
Self-Test Mode Select …etc.
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