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Reference Design of a 1-Wire® Bidirectional Voltage-Level Translator for 1.8V to 5V

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Description

Introduction

Devices such as FPGAs, microprocessors, the DS2482-100, and DS2480B are examples of 1-Wire master devices. The 1-Wire/iButton® slave devices are manufactured by Maxim and comprise an extensive family of parts that typically operate from 2.8V to 5.25V. The 1-Wire masters and slave devices have traditionally been 5V open-drain logic in the past. Today designers need open-drain logic to run at 1.8V at the 1-Wire master IO. While most 1-Wire slave devices can run safely at 5V, most of those same devices cannot run at 1.8V. A bidirectional voltage-level translator circuit is needed to overcome this limitation. This RD (reference design) features the Maxim® MAX3394E, which is a bidirectional voltage-level translator for these applications.

Voltage-Level Translator

The MAX3394E is a dual-level translator available in an 8-pin, 3mm x 3mm TDFN package. It is ideal for driving high-capacitive loads, thanks to its internal slew-rate enhancement circuitry. 1-Wire slave devices often have capacitive loading greater than 500pF. The MAX3394E's VCC I/O pins are protected to ±15kV HBM (Human Body Model), which protects the 1-Wire master. The 1-Wire bus architectures often interface to the external world, making HBM essential. However, it is recommended that a DS9503P be added as ESD protection for the pullup resistor (R3), the optional strong pullup circuitry, and the 1-Wire slave device.

Application Circuit

The circuit in Figure 1 shows the MAX3394E used to perform bidirectional 1.8V to 5V voltage-level translation in an open-drain system.

Figure 1. Schematic of 1-Wire bidirectional voltage level translation from 1.8V to 5V. Note that the pins I/O VL and I/O VCC have a typical 10kΩ internal pullup. The BOM (bill of materials) for this reference design is given in Table 1.

Table 1. Bill of Materials
Item Quantity Reference Part Manufacturer Part Number
1 1 C1 1.0µF 0402 Panasonic ECJ-0EB0J105M
2 2 C2, C3 0.1µF 0201 Panasonic ECJ-ZEB0J104K
3 1 Q1 BSS84-7-F Diodes, Inc/Zetex BSS84-7-F
4 1 R1 33Ω 0201 Panasonic ERJ-1GEJ330C
5 1 R2 10kΩ 0402 Panasonic ERJ-2RKF1002X
6 1 R3 1kΩ 0402 Panasonic ERJ-2RKF1001X
7 1 R4 2.2kΩ 0402 Panasonic ERJ-2RKF2201X
8 2 CH1, CH2 TEST POINT N/A N/A
9 1 U1 MAX3394E Maxim MAX3394EETA+

Waveform Measurements/Test Results

The test results in Figures 2 through 5 were generated from the board built for evaluating the circuit. Setup:

  • VL = 1.8V
  • VCC = 5.0V
  • CH1: 1-Wire master (OW_MASTER)
  • CH2: DS1920 (OW_SLAVE)
  • OW_SLAVE wire length: 2.4m, max.
  • Test results did not include the optional strong pullup circuitry in Figure 1.
  • Room temperature measurements only

Figure 2. The scope plot of a 1-Wire Reset shows the performance of the MAX3394E with presence pulse amplitude of no more than 250mV, lower than a typical 1-Wire master VIL maximum of 0.4V.
Figure 2. The scope plot of a 1-Wire Reset shows the performance of the MAX3394E with presence pulse amplitude of no more than 250mV, lower than a typical 1-Wire master VIL maximum of 0.4V.

Figure 3. The scope plot of a 1-Wire Write, one timeslot with a clean tLOW1 < 15µs.

Figure 4. The scope plot of a 1-Wire Write, zero timeslot with 60µs < tLOW0 < 120µs.
Figure 5. The scope plot of a 1-Wire Read, zero timeslot with an active 1-Wire slave open-drain return and lower than a typical 1-Wire master VIL maximum of 0.4V.
Figure 5. The scope plot of a 1-Wire Read, zero timeslot with an active 1-Wire slave open-drain return and lower than a typical 1-Wire master VIL maximum of 0.4V.

Conclusion

This RD for 1.8V to 5V 1-Wire bidirectional logic-level translation drives typical 1-Wire slave devices. The design was built and then tested. The circuit schematic, BOM, and typical waveforms have been presented.

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Designed, Built, Tested

Board pictured here has been fully assembled and tested. Not available for sale.

 

Maxim Devices (27)

Part Number Name Product Family Order Design kits and evaluation modules
DS1972 iButton 1024-Bit EEPROM Memory Buy Now Not Available
DS1961S iButton 1Kb EEPROM with SHA-1 Engine Memory Buy Now Not Available
DS1971 iButton 256-Bit EEPROM Memory Buy Now Not Available
DS1920 Temperature iButton iButton Buy Now Not Available
DS1822 Econo 1-Wire Digital Thermometer Sensors Buy Now Not Available
DS18B20-PAR 1-Wire Parasite-Power Digital Thermometer Sensors Buy Now Not Available
DS1973 iButton 4Kb EEPROM Memory Buy Now Not Available
DS1922E iButton High-Temperature Logger with 8KB Data-Log Memory Data Loggers Buy Now Not Available
DS1921Z High-Resolution Thermochron iButton Devices Data Loggers Buy Now Design Kits
DS1921H High-Resolution Thermochron iButton Devices Data Loggers Buy Now Design Kits
DS1921G Thermochron iButton Device Data Loggers Buy Now Design Kits
DS1977 iButton 32KB EEPROM Memory Buy Now Not Available
DS28E04-100 4096-Bit Addressable 1-Wire EEPROM with PIO Memory Buy Now Not Available
DS28E01-100 1Kb Protected 1-Wire EEPROM with SHA-1 Engine Secure Authentication Buy Now Design Kits
DS2450 1-Wire Quad A/D Converter Analog-to-Digital Converters Buy Now Not Available
DS2432 1Kb Protected 1-Wire EEPROM with SHA-1 Engine Memory Buy Now Not Available
DS2431 1024-Bit 1-Wire EEPROM Memory Buy Now Design Kits
MAX3394E ±15kV ESD-Protected, High-Drive Current, Dual-/Quad-/Octal-Level Translators with Speed-Up Circuitry Level Translators Buy Now Design Kits
DS1923 iButton Hygrochron Temperature/Humidity Logger with 8KB Data-Log Memory Data Loggers Buy Now Not Available
DS28EA00 1-Wire Digital Thermometer with Sequence Detect and PIO Sensors Buy Now Design Kits
DS28EC20 20Kb 1-Wire EEPROM Memory Buy Now Design Kits
DS18S20 1-Wire Parasite-Power Digital Thermometer Sensors Buy Now Not Available
DS18S20-PAR Parasite-Power Digital Thermometer Sensors Buy Now Not Available
DS18B20 Programmable Resolution 1-Wire Digital Thermometer Sensors Buy Now Design Kits
MAX31826 1-Wire Digital Temperature Sensor with 1Kb Lockable EEPROM Sensors Buy Now Design Kits
MAX31820 1-Wire Ambient Temperature Sensor Sensors Buy Now Not Available
MAX31820PAR 1-Wire Parasite-Power, Ambient Temperature Sensor Sensors Buy Now Not Available

Maxim Devices (27)

Part Number Product Family
Memory
iButton 1024-Bit EEPROM
Not Available
Memory
iButton 1Kb EEPROM with SHA-1 Engine
Not Available
Memory
iButton 256-Bit EEPROM
Not Available
iButton
Temperature iButton
Not Available
Sensors
Econo 1-Wire Digital Thermometer
Not Available
Sensors
1-Wire Parasite-Power Digital Thermometer
Not Available
Memory
iButton 4Kb EEPROM
Not Available
Data Loggers
iButton High-Temperature Logger with 8KB Data-Log Memory
Not Available
Data Loggers
High-Resolution Thermochron iButton Devices
Data Loggers
High-Resolution Thermochron iButton Devices
Data Loggers
Thermochron iButton Device
Memory
iButton 32KB EEPROM
Not Available
Memory
4096-Bit Addressable 1-Wire EEPROM with PIO
Not Available
Secure Authentication
1Kb Protected 1-Wire EEPROM with SHA-1 Engine
Analog-to-Digital Converters
1-Wire Quad A/D Converter
Not Available
Memory
1Kb Protected 1-Wire EEPROM with SHA-1 Engine
Not Available
Memory
1024-Bit 1-Wire EEPROM
Level Translators
±15kV ESD-Protected, High-Drive Current, Dual-/Quad-/Octal-Level Translators with Speed-Up Circuitry
Data Loggers
iButton Hygrochron Temperature/Humidity Logger with 8KB Data-Log Memory
Not Available
Sensors
1-Wire Digital Thermometer with Sequence Detect and PIO
Memory
20Kb 1-Wire EEPROM
Sensors
1-Wire Parasite-Power Digital Thermometer
Not Available
Sensors
Parasite-Power Digital Thermometer
Not Available
Sensors
Programmable Resolution 1-Wire Digital Thermometer
Sensors
1-Wire Digital Temperature Sensor with 1Kb Lockable EEPROM
Sensors
1-Wire Ambient Temperature Sensor
Not Available
Sensors
1-Wire Parasite-Power, Ambient Temperature Sensor
Not Available

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