DS1825 Programmable Resolution 1-Wire Digital Thermometer With 4-Bit ID www.maxim-ic.com FEATURES PIN ASSIGNMENT Unique 1-Wire Interface Requires Only One Port Pin for Communication 1 8 Each Device has a Unique 64-Bit Serial Code V AD3 DD Stored in an On-Board ROM Multidrop Capability Simplifies Distributed 2 7 Temperature-Sensing Applications AD2 DQ 4 Pin-Programmable Bits to Uniquely Identify DS1825 Up to 16 Sensor Locations on a Bus 6 3 8-pin SOP Requires No External Components AD1 N.C. (DS1825U) Can be Powered from Data Line. Power Supply Range: 3.0V to 3.7V 5 4 AD0 Measures Temperatures from -55C to +125C GND (-67F to +257F) 0.5 C Accuracy from -10C to +85C SOP Thermometer Resolution is User-Selectable (DS1825U) from 9 to 12 Bits Converts Temperature to 12-Bit Digital Word in 750ms (max) User-Definable (NV) Alarm Settings PIN DESCRIPTION Alarm Search Command Identifies and GND - Ground Addresses Devices Whose Temperature is DQ - Data In/Out Outside of Programmed Limits (Temperature N.C. - No Connect Alarm Condition) V - Power Supply Voltage DD AD0 to AD3 - Address Pins Available in 8-Pin SOP Package Software Compatible with the DS1822 APPLICATIONS Thermostatic Controls Industrial Systems 1-Wire is a registered trademark of Dallas Semiconductor. Consumer Products Thermometers Thermally-Sensitive Systems DESCRIPTION The DS1825 digital thermometer provides 9 to 12-bit centigrade temperature measurements and has an alarm function with NV user-programmable upper and lower trigger points. The DS1825 communicates over a 1-Wire bus that by definition requires only one data line (and ground) for communication with a central microprocessor. It has an operating temperature range of -55C to +125C and is accurate to 0.5 C over the range of -10C to +85C. In addition, the DS1825 can derive power directly from the data line (parasite power), eliminating the need for an external power supply. ORDERING INFORMATION ORDERING NUMBER PACKAGE MARKING DESCRIPTION DS1825U 1825 8-pin SOP DS1825U/T&R 1825 8-pin SOP Tape-and-Reel DS1825U+ 1825 (See Note 1) 8-pin SOP, Lead Free DS1825U+T&R 1825 (See Note 1) 8-pin SOP Tape-and-Reel, Lead Free Note 1: Additionally, a symbol will be marked on the package. 1 of 21 Rev 020105 DS1825 Programmable Resolution 1-Wire Digital Thermometer With 4-Bit ID DESCRIPTION (cont.) Each DS1825 has a unique 64-bit serial code, which allows multiple DS1825s to function on the same 1-Wire bus thus, it is simple to use one microprocessor to control many DS1825s distributed over a large area. In addition, the 4-bit location address can be used to identify specific temperature sensors in the system without requiring a wide lookup table. Applications that can benefit from this feature include HVAC environmental controls, temperature monitoring systems inside buildings, equipment or machinery, and process monitoring and control systems. ABSOLUTE MAXIMUM RATINGS* Voltage on Any Pin Relative to Ground -0.5V to +6.0V Operating Temperature Range -55 C to +125 C Storage Temperature Range -55 C to +125 C Solder Dip Temperature (10s) +260 C Reflow Oven Temperature +220 C These are stress ratings only and functional operation of the device at these or any other conditions above those indicated in the operation sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect reliability. DC ELECTRICAL CHARACTERISTICS (-55C to +125C V = 3.0V to 3.7V) DD PARAMETER SYMBOL CONDITION MIN TYP MAX UNITS NOTES Supply Voltage V Local Power +3.0 +3.7 V 1 DD Parasite Power +3.0 +3.7 Pullup Supply Voltage V V 1, 2 PU Local Power +3.0 V DD -10C to +85C 0.5 C Thermometer Error t 3 ERR -55C to +125C 2 C Programming R 0 10 12 k PGM Resistor: AD0-AD3 DQ Input Logic Low V -0.3 +0.7 V 1, 4, 5 IL(DQ) The lower of Local Power +2.2 3.7 DQ Input Logic High V V 1, 6 IH(DQ) or Parasite Power +3.0 V + 0.3 DD Sink Current I V = 0.4V 4.0 mA 1 L I/O Standby Current I 500 1000 nA 7, 8 DDS Active Current I V = 3.7V 0.65 1.5 mA 9 DD DD DQ Input Current I 5 A 10 DQ Drift 0.2 C 11 NOTES: 1. All voltages are referenced to ground. 2. The Pullup Supply Voltage specification assumes that the pullup device is ideal, and therefore the high level of the pullup is equal to V . PU In order to meet the V spec of the DS1825, the actual supply rail for the strong pullup transistor must include margin for the voltage drop IH across the transistor when it is turned on thus: V = V + V . PU ACTUAL PU IDEAL TRANSISTOR 3. See typical performance curve in Figure 18 4. Logic low voltages are specified at a sink current of 4mA. 5. To guarantee a presence pulse under low voltage parasite power conditions, V may have to be reduced to as low as 0.5V. ILMAX 6. Logic high voltages are specified at a source current of 1mA. 7. Standby current specified up to 70 C. Standby current typically is 3 A at 125 C. 8. To minimize I , DQ should be within the following ranges: GND DQ GND + 0.3V or V - 0.3V DQ V . DDS DD DD 9. Active current refers to supply current during active temperature conversions or EEPROM writes. 10. DQ line is high (hi-Z state). 11. Drift data is based on a 1000 hour stress test at 125C. 12. Inputs AD0-AD3 must be tied either High or Low. ALo is a connection to the GND terminal. AHig connection varies with usage of the DS1825. When connected as a parasite powered sensor, a connection to DQ is considered a High. When powered through the V DD pin, a connection to V is a High. If left floating, the input values are indeterminate and may be either logical0 or logical1 See DD Figures 20 and 21 for details. When optional programming resistors are used, their maximum values are 10,000 . 2 of 21