MAX14626 High-Voltage Reverse-Input-Capable 4 20mA Current Loop Protector

Transcription

1 ; Rev ; 3/12 EVALUATION KIT AVAILABLE General Description The current loop protector features a currentlimit switch to prevent damage to the sensor devices due to faulty current loop conditions. The current-limit switch features a 25I (typ) on-resistance and operates from a +2.3V to +36V input voltage range. The accurate current limit is set to 3mA, making the part ideal for protecting the sensor reading devices. The handles an overcurrent event in a continuous current-limit mode. Additional safety features include thermal shutdown to prevent overheating and reverse-input blocking to protect from being reverse connected into the sensor. The device is available in a tiny 6-pin (3mm x 3mm), TDFN exposed pad package and is specified over the -NC to +85NC extended temperature range. Industrial Current Loop Control Applications Benefits and Features S High Performance Low On-Resistance 25I (typ) Accurate Q% Current Limit +2.3V to +V Wide Supply Voltage Range Low Operating Current Ultra-Low Temperature Coefficient S Robust Protection for Sensors Avoids Power Dissipation Issues Compared to Discrete Solutions Thermal Shutdown Reverse Input Protection S Saves Space in Compact Systems Eliminates Need for Discrete PTC Poly Switch, Zener Diodes, and Resistors 3mm x 3mm, 6-Pin TDFN Package Ordering Information appears at end of data sheet. For related parts and recommended products to use with this part, refer to Typical Operating Circuit 4 2mA CURRENT SENSOR (4 2mA) CURRENT IN OUT REF SUPPLY CONTROL AND PROTECTION CURRENT LIMIT GATE CONTROL R LOAD IA ADC GND Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim Direct at , or visit Maxim s website at

2 ABSOLUTE MAXIMUM RATINGS (All voltages referenced to GND.) IN to GND...-V to +V OUT to GND V to +V Current into IN... Internally Limited Current into OUT...mA Continuous Power Dissipation (T A = +7NC) TDFN (derate 23.8mW/NC above +7NC) mW TDFN Junction-to-Ambient Thermal Resistance (B JA )... 42NC/W Operating Temperature Range... -NC to +125NC Maximum Junction Temperature...+1NC Storage Temperature Range NC to +1NC Lead Temperature (soldering, s)...+3nc Soldering Temperature (reflow)...+26nc Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. PACKAGE THERMAL CHARACTERISTICS (Note 1) Junction-to-Case Thermal Resistance (B JC )... 9NC/W Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a fourlayer board. For detailed information on package thermal considerations, refer to DC ELECTRICAL CHARACTERISTICS (I IN = FA to 24mA, T A = -NC to +85NC, R LOAD = 25I to 1kI, unless otherwise noted. Typical values are at I IN = ma, R LOAD = 2I, and T A = +25NC.) (Note 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS SUPPLY VOLTAGE Operating Start Voltage V IN_ST I IN = 2FA 2.3 V Operating IN Voltage V IN 36 V Operating IN to OUT Drop Voltage Quiescent Current (Normal Mode: 4 2mA) Quiescent Current (Current- Limit Mode: Current > 25mA) I IN = 24mA 2.8 V I Q R LOAD P 2I 56 FA I Q I OUT = 3mA, V IN = 5V, R LOAD = 25I 65 FA Reverse Current I REV V IN = -36V, V OUT = V, current into OUT.1.3 FA IN to OUT Switch On-Resistance R ON V IN = 4V, I OUT = 16mA I Forward Current Limit I LIM V IN = 36V ma DYNAMIC Turn-On Time t SS V IN = 3V, time from V IN applied to V OUT = 9% of V IN (Note 3) Fs Turn-Off Time t OFF Time from thermal shutdown (Note 3) 2 Fs Current-Limit Reaction Time t LIM Input current source from 2mA to ma (Note 4) Fs Current-Limit Overshoot Voltage Input current source from ma to ma % Input Small Signal Bandwidth BW 2mA P DC I IN P 24mA, DI IN = 1mA P-P at 1kI > khz Maxim Integrated Products 2

3 DC ELECTRICAL CHARACTERISTICS (continued) (I IN = FA to 24mA, T A = -NC to +85NC, R LOAD = 25I to 1kI, unless otherwise noted. Typical values are at I IN = ma, R LOAD = 2I, and T A = +25NC.) (Note 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS THERMAL PROTECTION Thermal Shutdown +1 NC Thermal-Shutdown Hysteresis 2 NC Note 2: All devices are % production tested at T A = +25NC, unless otherwise noted. Limits over the -NC to +85NC operating temperature range are guaranteed by design. Note 3: Turn-on time and turn-off time are defined as the difference in the time between when the output voltage crosses % and 9% of the final output voltage. Note 4: Input current source can support voltage up to +V (absolute maximum). Current reaction time is defined as the settling time of the output current after a fault event. (V IN = 24V, I IN = ma, R LOAD = 2I, unless otherwise noted. Typical values are at T A = +25NC.) Typical Operating Characteristics 9 8 QUIESCENT I Q vs. V IN NO LOAD toc1 9 8 QUIESCENT I Q vs. I IN toc2 9 8 QUIESCENT I Q vs. TEMPERATURE toc3 QUIESCENT IQ (µa) QUIESCENT IQ (µa) R L = 2I QUIESCENT IQ (µa) I IN = ma I IN = ma I IN = 2mA I IN = 4mA R L = I V IN (V) I IN (ma) TEMPERATURE ( C) Maxim Integrated Products 3

4 Typical Operating Characteristics (continued) (V IN = 24V, I IN = ma, R LOAD = 2I, unless otherwise noted. Typical values are at T A = +25NC.) ON-RESISTANCE (I) ON-RESISTANCE vs. TEMPERATURE I OUT = ma V IN = +2.36V V IN = +5V 3 V IN = +24V 2 V IN = +12V TEMPERATURE ( C) toc4 REVERSE CURRENT (na) 3 2 REVERSE CURRENT vs. V OUT 2 3 V OUT (V) toc5 1) 2) I IN ma TO 2mA µs/div toc6 1) CH1 V OUT 2V µs 2) CH4 L IN mv µs V OUT 2V/div I IN ma /div SOFT CURRENT LIMIT: I IN 15mA TO 35mA toc7 FAULT RESPONSE (SHORT TO WIRE): I IN ma TO ma toc8 V OUT 1) 5V/div 1) V OUT 5V/div I IN 2) ma /div I IN 1) CH1 V OUT 5V µs 2) CH4 L IN mv µs 2) 1) CH1 V OUT 5V µs 2) CH4 L IN mv µs 2mA /div µs/div µs/div Maxim Integrated Products 4

5 Pin Configuration TOP VIEW OUT GND I.C *EP IN I.C. I.C. TQFN *CONNECT EP TO GND Pin Description PIN NAME FUNCTION 1 IN Power Input 2, 3, 4 I.C. Internally Connected. Connect I.C. to GND. 5 GND Ground 6 OUT Switch Output EP Exposed Pad. Connect EP to GND. Connect to a large ground plane to maximize thermal performance. Not intended as an electrical connection point. Maxim Integrated Products 5

6 Functional Diagram IN OUT REF SUPPLY CONTROL AND PROTECTION CURRENT LIMIT GATE CONTROL GND Detailed Description The current loop protector features a currentlimit switch to prevent damage to the sensor devices due to faulty current loop conditions. The current-limit switch features a 25I (typ) on-resistance and operates from a +2.3V to +36V input voltage range. The accurate current limit is set to 3mA, making the part ideal for protecting the sensor reading devices. The handles an overcurrent event in a continuous current-limit mode. Additional safety features include thermal shutdown to prevent overheating and reverse input blocking to protect from being reverse connected into the sensor. Reverse Input Protection The device features reverse input protection to protect the downstream sensor. When a reverse input voltage is detected, control circuitry turns off the internal FET and isolates the output from the input. Thermal Shutdown The device enters thermal shutdown when the die temperature exceeds +1NC (typ). In thermal shutdown, the internal FETs are turned off. When the die temperature drops by 2NC, the device turns back on automatically. Applications Information Figure 1 shows the device in a 4 2mA current loop sensor application. Exposed Pad and Layout Concerns Connect the exposed pad to a large ground plane to maximize thermal performance. The exposed pad is not intended as an electrical connection point. To optimize the switch response time to output shortcircuit conditions, it is very important to keep all traces as short as possible to reduce the effect of undesirable parasitic inductance. Maxim Integrated Products 6

7 VOLTAGE SPIKE AND RF SUPRESSION SENSOR (4 2mA) CURRENT +INPUT -INPUT R LOAD = 2I IA ADC + DC SUPPLY 19.2V TO 32V - CURRENT LOOP ANALOG INPUT MODULE VOLTAGE SPIKE AND RF SUPRESSION +INPUT -INPUT R LOAD = 2I IA ADC ANALOG INPUT MODULE Figure mA Current Loop Sensor Application PART ETT+T Ordering Information TEMP RANGE -NC to +85NC PIN- PACKAGE +Denotes a lead(pb)-free/rohs-compliant package. T = Tape and reel. *EP = Exposed pad. TOP MARK 6 TDFN-EP* AVF Chip Information Package Information For the latest package outline information and land patterns (footprints), go to Note that a +, #, or - in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. PACKAGE TYPE PACKAGE CODE DOCUMENT NO. LAND PATTERN 6 TDFN T PROCESS: BiCMOS Maxim Integrated Products 7

8 Revision History REVISION NUMBER REVISION DATE DESCRIPTION PAGES CHANGED 3/12 Initial release Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance. Maxim Integrated Products, 12 San Gabriel Drive, Sunnyvale, CA Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.