Descripción general

The MAX5180 contains two 10-bit, simultaneous update, current-output digital-to-analog converters (DACs) designed for superior performance in communications systems requiring analog signal reconstruction with low distortion and low-power operation. The MAX5183 provides equal specifications, with on-chip precision resistors for voltage output operation. The devices are designed for 10pVs glitch operation to minimize unwanted spurious signal components at the out put. An on-board 1.2V bandgap circuit provides a well-regulated, low-noise reference that can be disabled for external reference operation.

The MAX5180/MAX5183 are designed to provide a high level of signal integrity for the least amount of power dissipation. The DACs operate from a single supply of 2.7V to 3.3V. Additionally, these DACs have three modes of operation: normal, low-power standby, and complete shutdown, which provides the lowest possible power dissipation with 1µA (max) shutdown current. A fast wake up time (0.5µs) from standby mode to full DAC operation conserves power by activating the DACs only when required.

The MAX5180/MAX5183 are packaged in a 28-pin QSOP and are specified for the extended (-40°C to +85°C) temperature range. For lower-resolution, dual 8-bit versions, refer to the MAX5186/MAX5189 data sheet.

 

Características

♦ 2.7V to 3.3V Single-Supply Operation

♦ Wide Spurious-Free Dynamic Range: 70dB at fOUT = 2.2MHz

♦ Fully Differential Outputs for Each DAC

♦ ±0.5% FSR Gain Mismatch

♦ ±0.2° Phase Mismatch

♦ Low-Current Standby or Full-Shutdown Modes

♦ Internal 1.2V Low-Noise Bandgap Reference

♦ Small 28-Pin QSOP Package

 

Aplicaciones

Signal Reconstruction of I and Q Transmit

Signals

Digital Signal Processing

Arbitrary Waveform Generation (AWG)Imaging

 

Descripción detallada

log converters (DACs) capable of operating with clock speeds up to 40MHz. Each of these dual converters consists of separate input and DAC registers, followed by a current source array capable of generating up to 1.5mA full-scale output current (Figure 1). An integrated 1.2V voltage reference and control amplifier deter mine the data converters’ full-scale output currents/ voltages. Careful reference design ensures close gain matching and excellent drift characteristics. The MAX5183’s voltage output operation features matched 400Ω on-chip resistors that convert the current array current into a voltage.

Internal Reference and Control Amplifier

The MAX5180/MAX5183 provide an integrated 50ppm/°C, 1.2V, low-noise bandgap reference that can be disabled and overridden by an external reference voltage. REFO serves either as an external reference input or an integrated reference output. If REN is connected to AGND, the internal reference is selected and REFO provides a 1.2V output. Due to its limited 10µ Aoutput drive capability, REFO must be buffered with an external amplifier, if heavier loading is required.
The MAX5180/MAX5183 also employ a control amplifier designed to simultaneously regulate the full-scale out put current (IFS) for both outputs of the devices. The output current is calculated as follows:

IFS = 8 × IREF

where IREF is the reference output current (IREF = VREFO/RSET) and IFS is the full-scale output current. RSET is the reference resistor that determines the amplifier’s output current on the MAX5180 (Figure 2). This current is mirrored into the current-source array where it is equally distributed between matched current segments and summed to valid output current readings for the DACs.

The MAX5183 converts each output current (DAC1 and DAC2) into an output voltage (VOUT1, VOUT2) with two internal, ground-referenced 400Ω load resistors. Using the internal 1.2V reference voltage, the MAX5183’s integrated reference output current resistor (RSET = 9.6kΩ) sets IREF to 125µA and IFS to 1mA.

External Reference

To disable the MAX5180/MAX5183’s internal reference, connect REN to AVDD. A temperature-stable, external reference may now be applied to drive the REFO pin to set the full-scale output (Figure 3). Choose a reference capable of supplying at least 150µA to drive the bias circuit that generates the cascode current for the cur rent array. For improved accuracy and drift performance, choose a fixed output voltage reference such as the 1.2V, 25ppm/°C MAX6520 bandgap reference.