With the addiTIon of a few inexpensive miniature components, the hard-wired, voltage-controlled current source of yesterday becomes a software-programmable voltage-controlled current source (Figure 1).
A digital potenTIometer (U1) in conjunction with a precision op amp (U2) sets current through the pass transistor (ISET), and a shunt regulator (U3) provides a constant reference voltage across the digital pot. By operating in its linear region, the transistor controls load current in response to the applied gate voltage. Each incremental step of the digital pot increases or decreases the voltage VIN + at the op amp's noninverting input. Thus, the pot's wiper voltage (VIN +) varies with respect to the reference voltage, which in turn remains stable with respect to the supply rail:
Many types of digital potentiometers are currently available, and the interface to these devices (besides the hard-wired type) can be one, two, or three wires. U1, for example, has a 3-wire SPI interface, and provides an end -to-end resistance of 50kΩ with 256 incremental settings. Thus, each increment of the digital pot changes VIN + by:
Op amp U2 regulates current through the pass transistor, and the digital pot sets current through the RSENSE resistor. The voltage across RSENSE determines current through the pass transistor (ISET):
The circuit can provide any current level for which the external components (RSENSE and the pass transistor) can handle the associated power dissipation (P = IV). Because the ratio setting of digital potentiometers is very good (the typical ratiometric resistor tempco is 5ppm / ° C), precision and stability for the current source depends primarily on the precision and stability of U3 and RSENSE combined.
Figure 1. This software-programmable, precision current source applies current to the load in 256 equal increments.
A similar version of this article appeared in the December 17, 2004 issue of EDN magazine.
Waterproof D-Sub Connector & D-SUB Adapter
IP66 / IP67 waterproof d-sub connectors-Designed for IP Performance
ANTENK has developed IP66 / IP67 waterproof d-sub connectors that utilize a proprietary sealing technology, which maintains the same physical size and footprint as standard d-sub products.
Antenk's line of Waterproof d-sub connectors utilize an innovative sealing technology eliminating the need to redesign enclosures and PC boards when implementing IP67 design upgrades.These connectors are designed for applications that require protection from heavy spray or are exposed to short-term submersion. Connectors are available in vertical and right angle board mount types as well as solder cup for panel mount cable applications. Standard D-Subs are available in 9 pin, 15 pin, and 25 pin positions, and high density D-Subs are available in 15 pin, 26 pin, and 44 pin positions
Applications of Antenk waterproof d-sub connectors:
Hand held computers, scanners, and printers that are used outdoors
Remote sensors, gauges, and data loggers that are used outdoors
Industrial and Medical equipment that is routinely subject to wash down
Transmitters and emergency beacons that are subject to temporary submersion
Gas, Electric, and Water metering systems that have embedded Smart Grid electronics
Portable electric generation equipment (Gen Sets)
Consumer and Commercial boating electronics (Radios, Scanners, Radar, DC Power Ports)
IP67 D-SUB | WATERPROOF CONNECTORS FEATURES & BENEFITS
Signal / Low Power in 6 standard size
(Standard: 9 pin, 15 pin, 25 pin | High Density: 15 pin, 26 pin,44 pin)
Combo-D / High Power in a variety of configurations:
(3W3, 5W5, 7W2, 9W4, 11W1, 13W3, 13W6, 17W2, 21W1, 21WA4)
Solder Cup, Vertical Mount & Right Angle Board Mount Options
High Reliability Screw Machined Contacts
3 amp / 5 amp / 20 amp / 40 amp Power Options
-65°C to +105°C Operating Temperature Range
Range of Antenk waterproof d-sub connectors
solder cup, stamped & formed contact D-sub waterproof
solder cup,machined contacts D-sub waterproof
vertical mount D-sub waterproof
right angle D-sub waterproof
IP67 rated Combo power D-sub waterproof
D-Sub adapters, couplers, and splitters
Solder Cup Waterproof D-Sub Connector,Vertical Mount Waterproof D-Sub Connector, Right Angle Waterproof D-Sub Connector,Combo Power D-Sub Waterproof D-Sub Connector,Waterproof D-Sub Connector,D-SUB Adapter,IP66/ IP67/IP68 Rated D-Sub Connectors
ShenZhen Antenk Electronics Co,Ltd , https://www.antenksocket.com