DS2490X datasheet, PDF - EEWORLD Datasheet

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DS2490X: DescriptionBus Controller, CMOS,; CategoryThe embedded processor and controller Microcontrollers and processors; File Size462KB，50 Pages; ManufacturerDALLAS; Websitehttp://www.dalsemi.com

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DS2490X Overview

Bus Controller, CMOS,

DS2490X Parametric

Parameter Name	Attribute value
Is it Rohs certified?	incompatible
Maker	DALLAS
Reach Compliance Code	unknown
JESD-609 code	e0
Maximum operating temperature	70 °C
Minimum operating temperature
Package body material	CERAMIC
Encapsulate equivalent code	FLIP CHIP
power supply	3.3,5 V
Certification status	Not Qualified
technology	CMOS
Temperature level	COMMERCIAL
Terminal surface	Tin/Lead (Sn/Pb)

DS2490X Preview

DS2490

USB to 1-Wire Bridge Chip

www.maxim-ic.com

FEATURES

Communicates at regular and overdrive 1-

Wire

speeds

Supports 12V EPROM programming and stiff

5V pullup for EEPROM, sensors, and crypto

iButton

Slew rate controlled 1-Wire timing and active

pullup to accommodate long 1-Wire network

lines and reduce radiation

Programmable 1-Wire timing and driver

characteristics accommodate a wide range of

1-Wire network configurations

Low- to high-level command types, including

macros, for generating 1-Wire communication

Crystal oscillator timebase provides precision

timed 1-Wire waveforms

High-speed 12Mbps Universal Serial Bus

(USB) interface

Integrated USB-compliant transceiver

Supports USB remote wake-up from a 1-Wire

device event to resume a suspended host

system

C to +70

C operating temperature range

PIN ASSIGNMENT

24-Pin SO

Top View

(300-mil)

PMOD

SUSO

D-

D+

1-WIRE

GND

VPP

Flip-Chip Package, Top View

SUSO\

D-

GND

4.4 mm

PMOD

D+

VDD

7.1 mm

VPP

ORDERING INFORMATION

PART NUMBER

DS2490S

DS2490S/T&R

DS2490X

PACKAGE DESCRIPTION

24-pin SO

Tape & Reel of DS2490S

Flip-Chip Package, Tape & Reel

DESCRIPTION

The DS2490 is a bridge chip that enables communication between a USB host system and a 1-Wire bus.

It provides regular, overdrive, and flexible 1-Wire communication speeds and a full-speed 12Mbps

connection to USB. USB vendor-specific commands defined in this specification are used to control the

DS2490 and communicate with attached 1-Wire devices. A functional block diagram of the DS2490 is

shown in Figure 1.

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120401

DS2490

SIGNAL SUMMARY

Table 1

SIGNAL NAME

VPP

D+

D-

1-Wire

PMOD

TYPE

PWR

I/O

FUNCTION

Power supply input for digital and 1-Wire functions. Range: 5.0

10%

Power supply input for 1-Wire EPROM programming. Range:

12V

0.25V

Power supply input for USB functions. Range: 3.3V

10% supply

regulated from USB supplied VBUS.

USB data—non-inverted of differential data pair.

USB data—inverted signal of differential data pair.

1-Wire input/output.

Reserved for future use. Must be tied to GND.

Suspend Output—buffered USB suspend-state output from USB device

controller. When HIGH the USB is in an active non-suspended state,

when LOW the USB has entered a suspended state. This is an open drain

output and requires an external pullup.

Crystal input. Use a 12.0 MHz, fundamental-mode, parallel-resonant

crystal. A 12.0MHz CMOS clock source may also be used.

Crystal output. Connect to other side of crystal 1 if used.

Ground reference and ground return for 1-Wire bus.

No connect. For factory use or reserved, do not connect to these pins.

SUSO

GND

PWR

RELATED DOCUMENTS

This specification uses terms from and references or complies with the

Universal Serial Bus Specification

v1.1,

which may be obtained from the USB Implementers Forum website: www.usb.org. The USB

specification is considered to be part of the DS2490 specification.

DOCUMENT ORGANIZATION

The remainder of this document is organized into the following major sections:

SECTION

OVERVIEW

1-WIRE I/F CONTROLLER

USB COMMUNICATION

SUMMARY

Device functional summary and application examples

Edge control and timing diagrams of 1-Wire signals

Configuration model, core and vendor-specific command

summaries

Commands used to configure 1-Wire interface operational

characteristics

Commands used to control 1-Wire communication

command processing

Commands used to communicate with an attached 1-Wire

device

Technique to obtain device status information

Transceiver connection requirements

Oscillator connection requirements

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MODE COMMANDS

CONTROL COMMANDS

COMMUNICATION COMMANDS

DEVICE FEEDBACK

USB TRANSCEIVER

OSCILLATOR

DS2490

SECTION

SUSPEND OUTPUT

ELECTRICAL CHARACTERISTICS

APPLICATION INFORMATION

APPENDIX 1

APPENDIX 2

APPENDIX 3

APPENDIX 4

SUMMARY

SUSO signal operation and purpose

DC and AC specifications

HW application example

CONTROL COMMANDS—USB setup packet encoding

COMMUNICATION COMMANDS—USB setup packet

encoding

MODE COMMANDS—USB setup packet encoding

USB command and command type constant codes

OVERVIEW

The DS2490 directly interfaces a USB port to a 1-Wire bus. As shown in Figure 1, the DS2490

incorporates a USB physical interface, a USB device controller coupled with a 1-Wire-specific USB

function core, and a 1-Wire bus interface controller. The 1-Wire interface controller shapes the slopes of

the 1-Wire waveforms, applies programming pulses or strong pullup to 5V, and reads the 1-Wire bus

using a non-TTL threshold to maximize the noise margin for best performance on large 1-Wire Networks.

1-Wire waveform timing is accurately controlled with a crystal-based oscillator.

The DS2490 also supports USB remote wake-up which enables the DS2490-based USB peripheral to

send resume signaling to a suspended host system. If the remote wake-up function is enabled and the host

system is in a suspended state, a 1-Wire device attachment will cause the DS2490 to perform a host

system wake-up and allow the 1-Wire device to be serviced.

DS2490 FUNCTIONAL BLOCK DIAGRAM

Figure 1

SUSO

USB

DESC

ROM

1-WIRE

I/F

CONTROLLER

D+

D-

USB

XCVR

USB

DEVICE

CONTROLLER

USB

1-WIRE

FUNCTION

CORE

FIFOS

1-WIRE

PWR

CNTL

OSC

CLK

GEN

GND

VPP

Typical application examples of the DS2490 are shown in Figure 2 (a to c). As shown in all the examples,

all host control and communication with the device is accomplished over a USB communication link. A

USB vendor-specific command set, as defined in this document, is used to select operational modes

(MODE COMMANDS), control command processing (CONTROL COMMANDS), and communicate

over the 1-Wire interface (COMMUNICATION COMMANDS). Shown in Figure 2, example (a) is a

DS2490-based USB peripheral application. The peripheral function is a USB to 1-Wire adapter and

provides both USB and 1-Wire I/O connections. In this example, the peripheral is attached to the USB

enabled host computer either directly at a root port or through a USB hub. The 1-Wire bus interface

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DS2490

provided by the DS2490 supports all 1-Wire devices manufactured by Dallas Semiconductor as well as

the various 1-Wire bus topologies simple multi-drop to complex 1-Wire Network. Example (b) and (c) in

Figure 2 are variations of example (a) in which the DS2490 is embedded in the host computer or a USB

HUB.

DS2490 APPLICATION EXAMPLES

Figure 2

1-WIRE INTERFACE CONTROLLER

1-Wire communication commands sent to the DS2490 are ultimately processed by the 1-Wire interface

controller. One of the tasks of the interface controller is to actively shape the edges of the 1-Wire

communication waveforms. This speeds up the recharging of the 1-Wire bus (rising edges) and reduces

ringing of long lines (falling edges). The circuitry for shaping rising edges is always active. The slew rate

of falling edges is actively controlled only at flexible speed and requires the parameter for slew rate

control being different from its power-on default value. See the MODE COMMANDS section for

parameter control and power-on defaults.

All Rising Edges

The active pullup of the rising edges reduces the rise time on the 1-Wire bus significantly compared to a

simple resistive pullup. Figure 3 shows how the DS2490 is involved in shaping a rising edge.

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DS2490

ACTIVE PULLUP

Figure 3

IAPTO

APUOT

IAPO

1-Wire bus

is discharged

The circuit operates as follows: At t

the pulldown (induced by the DS2490 or a device on the bus) ends.

From this point on the 1-Wire bus is pulled high by the weak pullup current I

WEAKPU

provided by the

DS2490. The slope is determined by the load on the bus and the value of the pullup current. At t

the

voltage crosses the threshold voltage V

IAPO

. Now, the DS2490 switches over from the weak pullup

current I

WEAKPU

to the higher current I

ACTPU

. As a consequence, the voltage on the bus now rises faster.

As the voltage on the bus crosses the threshold V

IAPTO

at t

, a timer is started. As long as this timer is on

APUOT

), the I

ACTPU

current will continue to flow. After the timer is expired, the DS2490 will switch back

to the weak pullup current.

Falling Edges (DS2490-initiated)

Whenever the DS2490 begins pulling the 1-Wire bus low to initiate a time slot, for example, it first turns

off the weak pullup current I

WEAKPU

. Then, at regular and overdrive speed it will generate a falling edge at

a slew rate of typically 15 V/µs. This value is acceptable for short 1-Wire busses and adequate for

communication at overdrive speed. For 1-Wire networks of more than roughly 30m length, flexible speed

should always be used. One of the parameters that is adjustable at flexible speed is the slew rate of

DS2490-initiated falling edges. The effect of the slew rate control is shown in Figure 4.

SLEW RATE CONTROL

Figure 4

Target for

long lines:

4 ± 0.5 µs

low slew rate

high slew rate

0.8 V

1-Wire bus

is pulled up

weak pull-up ends,

pull-down begins

Extensive tests have shown that 1-Wire networks with lengths of up to 300m will perform best if the fall

time t

is in the range of 4 ± 0.5µs. This translates into a slew rate of approximately 1V/µs. This slew rate

is typically achieved by selecting a PULLDOWN SLEW RATE parameter code of 0 x 4 (see MODE

COMMANDS). If the actual measured fall time is longer than the target value, a parameter code of 0 x 3

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