Maxim Integrated MAXREFDES18 Carmel Reference Design provides a high-accuracy analog current/voltage output in a compact, galvanically isolated form factor. This design uniquely fits programmable logic controllers, distributed control systems, and other industrial applications. Maxim MAXREFDES18 Carmel design features a MAX5316 16-bit digital-to-analog converter that drives the input of a MAX15500 programmable analog output conditioner. The integrated MAX6126 ultra-high-precision voltage reference provides references for the DAC and the output conditioner. MAX14850 galvanically isolates data communication between the subsystem and the system controller. The subsystem also integrates an isolated and regulated power supply by using the MAX13253 transformer driver and the MAX1659 and MAX1735 low-dropout linear regulators.
MAX5316 is a high-accuracy, 16-bit, serial SPI input, buffered voltage output digital-to-analog converter (DAC) in a 4mm x 5mm, 24-lead TQFN package. The device features ±1 LSB INL (max) accuracy and a ±0.25 LSB DNL (typ) accuracy over the temperature range of -40°C to +105°C. The DAC voltage output is buffered with a fast settling time of 3µs and a low offset and gain drift of ±0.6ppm/°C of FSR (typ). The force-sense output (OUT) maintains accuracy while driving loads with long lead lengths. A separate AVSS supply is provided to permit the output amplifier to go to 0V (GND) to maintain full linearity performance near ground. At power-up, the device resets its outputs to zero or midscale. The wide 2.7V to 5.5V supply voltage range and integrated low-drift, low-noise reference buffer make for ease of use. The MAX5316 features a 50MHz 3-wire SPI interface.
Maxim MAX15500 Analog Current/Voltage Output Conditioners provide a programmable current up to ±24mA, or a voltage up to ±12V proportional to a control voltage signal. The control voltage is typically supplied by an external DAC with an output voltage range of 0 to 4.096V for the MAX15500. The output current and voltage are selectable as either unipolar or bipolar. In the unipolar configuration, a control voltage of 5% full-scale (FS) produces a nominal output of 0A or 0V to achieve underrange capability. A control voltage of 100%FS produces one of two programmable levels (105%FS or 120%FS) to achieve overrange capability. The outputs of the MAX15500 are protected against overcurrent conditions and a short to ground or supply voltages up to ±35V. The devices also monitor for overtemperature and supply brownout conditions. The supply brownout threshold is programmable.
Maxim MAX6126 Ultra-High-Precision, Ultra-Low-Noise, Series Voltage Reference is an ultra-low-noise, high-precision, low-dropout voltage reference. This family of voltage references feature curvature-correction circuitry and high-stability, laser-trimmed, thin-film resistors that result in 3ppm/°C (max) temperature coefficients and an excellent ±0.02% (max) initial accuracy. The proprietary low-noise reference architecture produces a low flicker noise of 1.3µVP-P and wideband noise as low as 60nV/√Hz (2.048V output) without the increased supply current usually found in low-noise references. Improve wideband noise to 35nV/√Hz and AC power-supply rejection by adding a 0.1µF capacitor at the noise reduction pin. Maxim MAX6126 series mode reference operates from a wide 2.7V to 12.6V supply voltage range and load-regulation specifications are guaranteed to be less than 0.025Ω for sink and source currents up to 10mA. These devices are available over the automotive temperature range of -40°C to +125°C.
Maxim's MAX14850 Six-Channel Digital Isolator utilizes Maxim's proprietary process technology, whose monolithic design provides a compact and low-cost transfer of digital signals between circuits with different power domains. The technology enables low power consumption and stable high-temperature performance. The four unidirectional channels are each capable of DC to 50Mbps, with two of the four channels passing data across the isolation barrier in each direction. The two bidirectional channels are open drain and each is capable of data rates from DC to 2Mbps. Independent 3.0V to 5.5V supplies on each side of the isolator also make it suitable for use as a level translator. The MAX14850 can be used for isolating SPI busses, I²C busses with clock stretching, RS-232, RS-485/RS-422 busses, and general-purpose isolation. When used as a bus isolator, extra channels are available for power monitoring and reset signals.
Maxim MAX13253 is a 1A push-pull transformer driver designed to provide a simple solution for low-EMI isolated power supplies. The MAX13253 has an internal oscillator and operates from a single +3.0V to +5.5V supply. The transformer’s secondary-to-primary winding ratio defines the output voltage, allowing selection of virtually any isolated output voltage with galvanic isolation. MAX13253 features an integrated oscillator driving a pair of N-channel power switches.
Maxim MAX1659 350mA, 16.5V Input, Low-Dropout Linear Regulators maximize battery life by combining ultra-low supply currents and low dropout voltages. They feature Dual Mode™ operation, which presets the output to 5V, or permits it to be adjusted between 1.25V and 16V. The regulator supplies up to 350mA, with a typical dropout of 650mV for the MAX1658 and 490mV for the MAX1659. With their P-channel MOSFET pass transistor, these devices maintain a low quiescent current from zero output current to the full 350mA, even in dropout. They support input voltages ranging from 2.7V to 16.5V. MAX1659 features a 1µA shutdown mode, reverse battery protection, short-circuit protection, and thermal shutdown. They are available in a special high-power (1.2W), 8-pin SO package designed specifically for compact applications.
Maxim MAX1735 negative-output, low-dropout linear regulator operates from a -2.5V to -6.5V input and delivers a guaranteed 200mA with a low 80mV dropout. The high-accuracy (±1%) output voltage is preset or can be adjusted from -1.25V to -5.5V with an external resistive voltage-divider. An internal N-channel MOSFET allows for a low 85µA quiescent current virtually independent of the load, making this device ideal for battery-powered portable equipment, such as PDAs, mobile phones, cordless phones, and wireless data modems. The device is available in several preset output voltage versions: -5.0V, -3.0V, and -2.5V. All versions offer a 1nA low-power shutdown mode, short-circuit protection, and thermal overload protection.