Analog Devices Inc. REF195ES

Overview

REF195ES from Analog Devices is a precision micropower low-dropout voltage reference IC delivering 5.00 V nominal output with ±2 mV initial accuracy, 5 ppm/°C max temperature coefficient, and 45 μA max supply current - used as a stable excitation source for high-resolution ADCs and DACs in portable instrumentation.

For engineers reviewing the REF195ES datasheet, REF195ES pinout, REF195ES application, or REF195ES equivalent, key selection criteria include dropout voltage (0.50 V at 10 mA), sleep-mode current (15 μA), load regulation (4 ppm/mA), and SOIC-8 package compatibility with Kelvin-sensing layouts in battery-powered sensor nodes.

Technical Context

The REF195ES employs a patented curvature-corrected band gap core with laser-trimmed thin-film resistors to achieve low drift across −40°C to +85°C. Its SLEEP pin enables TTL/CMOS-compatible shutdown, reducing quiescent current to ≤15 μA while disabling output.

It operates with input-to-output headroom as low as 100 mV above 5.00 V (i.e., VS ≥ 5.10 V), supports 30 mA output current, and requires a 1 μF output bypass capacitor for stability. Line regulation is specified at 4 ppm/V (E grade) and load regulation at 4 ppm/mA (E grade) at 25°C.

Key Specifications

Pinout & Package

REF195ES is housed in an 8-lead SOIC_N (SOIC-8) package (S suffix), with exposed pad not electrically connected. Pin 1 and Pin 5 are factory test points (TP) reserved for Zener-zap trimming and must remain unconnected in circuit.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar precision voltage reference applications.

Compared with REF195ES, ADR4550BRZ offers superior temperature stability but eliminates the integrated SLEEP function needed for burst-mode sensor systems, while MAX6126AASA50+ provides higher output current at the expense of triple the quiescent power - making REF195ES optimal for space- and energy-constrained portable instrumentation.

Availability

REF195ES is available at Aetrix Electronics and suitable for portable instrumentation, high-resolution data acquisition, and solar-powered remote sensors requiring stable component supply with guaranteed long-term parametric consistency.

Supply support for REF195ES includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Analog Devices is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, headquartered in Norwood, MA.

The REF19x series was designed specifically for micropower, low-dropout precision reference applications in battery-operated and energy-harvesting systems where accuracy, stability, and ultra-low quiescent current are critical.

FAQ

What is the minimum supply voltage required for stable operation of the REF195ES?

The REF195ES requires a minimum supply voltage of 5.50 V at 10 mA load (0.50 V dropout), and 5.10 V at no load. Operation below 5.10 V risks output regulation loss and increased noise; design margin should maintain VS ≥ 5.6 V for reliable performance across temperature and load variation. The REF195ES datasheet specifies dropout voltage as VS − VO, confirming 0.50 V at 10 mA.

Does the REF195ES require an output bypass capacitor, and what value is recommended?

Yes, the REF195ES requires a 1 μF ceramic capacitor between OUTPUT and GND for stability and noise reduction, as explicitly stated in the datasheet's Applications Information section. This capacitor minimizes high-frequency oscillation and suppresses 0.1–10 Hz noise (50 μV p-p). Larger values (e.g., 10 μF) may improve transient response but are not required for basic regulation. The REF195ES will not meet specifications without this capacitor.

How does the SLEEP pin function on the REF195ES, and what are its electrical thresholds?

The SLEEP pin on the REF195ES is an active-low TTL/CMOS-compatible control input. A logic low (≤0.8 V) disables the output and reduces supply current to ≤15 μA; a logic high (≥2.4 V) enables normal operation with ≤45 μA supply current. Input leakage is ≤−8 μA in both states. This feature enables precise power gating in duty-cycled systems - a key differentiator of the REF195ES versus non-sleep references.

Can the REF195ES drive a 30 mA load while maintaining its specified accuracy?

Yes, the REF195ES is rated for up to 30 mA output current while maintaining its full accuracy specifications, including ±2 mV initial error and 4 ppm/mA load regulation (E grade, 25°C). At 30 mA, dropout voltage rises to 1.30 V (VS = 6.30 V), and output voltage shift remains within datasheet limits. Load regulation of 4 ppm/mA means only 20 μV change per mA - well within the ±2 mV initial tolerance band. This capability is confirmed in Table 14 and Table 15 of the REF195ES datasheet.

What is the purpose of Pins 1 and 5 on the REF195ES, and how should they be handled in PCB layout?

Pins 1 and 5 on the REF195ES are factory test points (TP) used for Zener-zap trimming during production and must remain unconnected in all applications. Their resistance varies widely unit-to-unit and serves no functional role in circuit operation. PCB layout must leave these pins floating - neither routed nor tied to GND, VS, or any other net. This requirement is explicitly documented in the "Test Pins" section of the REF195ES datasheet to preserve output accuracy.