Microchip Technology CD827A

Overview

CD827A from Microsemi is a monolithic temperature-compensated zener reference die with nominal zener voltage 5.9–6.5 V, test current 7.5 mA, zener impedance 13 Ω, max voltage drift ±9 mV over –55°C to +100°C, and tempco 0.001 %/°C - used as precision voltage reference in high-reliability analog power supply monitoring circuits.

For engineers reviewing the CD827A datasheet, CD827A pinout, CD827A application, or CD827A equivalent, this part serves as a MIL-qualified, silicon-dioxide-protected zener die requiring cathode-positive biasing, compatible with wire bonding and die attach (excluding solder reflow), and specified for operation from –65°C to +175°C.

Technical Context

The CD827A is a bare die zener diode designed for hybrid and hermetic module integration, featuring full junction passivation via silicon dioxide to prevent contamination and leakage. Its temperature compensation architecture achieves ultra-low voltage drift (±9 mV) across –55°C to +100°C and a tight 0.001 %/°C effective temperature coefficient.

It operates under reverse-bias conditions with cathode positive relative to anode, requires no external series resistor for basic reference use at 7.5 mA, and exhibits 13 Ω dynamic impedance at I_ZT, enabling stable regulation in low-noise analog subsystems where long-term drift and thermal hysteresis must be minimized.

Key Specifications

Pinout & Package

CD827A is supplied as a bare die in JANHC/JANKC qualified ceramic or metal package format; backside must be electrically isolated. Die dimensions: 0.0280–0.0320" × 0.0280–0.0320" (0.711–0.813 mm square), thickness 0.010" ±0.002".

Key Features

Applications

Equivalent & Alternatives

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

Compared with CD829A and CD825A, the CD827A strikes a balanced trade-off between ultra-low drift and cost-effectiveness - offering ±9 mV drift and 0.001 %/°C tempco while maintaining full MIL-qualification and compatibility with existing hybrid assembly processes.

Availability

CD827A is available at Aetrix Electronics and suitable for avionics power monitoring, downhole sensor conditioning, and nuclear instrumentation requiring stable component supply across extended temperature and radiation environments.

Supply support for CD827A 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

Microsemi (now part of Microchip Technology) is a U.S.-based semiconductor company specializing in high-reliability analog, RF, and radiation-hardened components for defense, aerospace, and industrial markets.

The CD827A belongs to Microsemi's legacy MIL-qualified zener reference die family, engineered specifically for hybrid module integration in mission-critical systems where long-term voltage stability and environmental survivability are non-negotiable.

FAQ

What is the correct biasing polarity for CD827A?

The CD827A must be operated in reverse-bias mode with the cathode (Terminal 1) held positive relative to the anode (Terminal 2). This polarity is mandatory for zener breakdown and regulation. Applying forward bias will not produce regulation and may damage the device under sustained current. The CD827A datasheet explicitly states "for zener operation, cathode must be operated positive with respect to anode."

Is CD827A compatible with solder reflow assembly?

No, CD827A is not compatible with solder reflow assembly. The technical data sheet states it is "compatible with all wire bonding and die attach techniques with the exception of solder reflow." This restriction arises from thermal stress limitations on the bare die structure and metallization. Recommended attachment methods include conductive epoxy, thermosonic wire bonding, or eutectic die bonding - not reflow soldering.

What does the "A" suffix in CD827A signify?

Within the CD821–CD829A series, the "A" suffix denotes JANKC qualification level - a military screening grade that includes additional environmental testing (e.g., extended temperature cycling, burn-in, and hermeticity verification) beyond standard JANHC. The CD827A shares identical electrical specs with CD827 but meets stricter reliability and traceability requirements for critical applications.

Can CD827A replace 1N827 in a design?

Yes, CD827A is electrically equivalent to 1N827 per the datasheet statement "Electrically Equivalent to 1N821 Thru 1N829". However, CD827A is a bare die while 1N827 is a through-hole packaged diode. Direct replacement requires redesigning for die-level integration - including wire bonding, substrate layout, and isolation - and is not a drop-in PCB swap.

What is the purpose of the test pad (Terminal 3) on CD827A?

The test pad (Terminal 3) on CD827A is a dedicated aluminum metallization area intended solely for wire bond process evaluation during manufacturing. It makes no electrical connection to the zener junction and must not be bonded or contacted in final application. Its presence supports quality assurance but contributes zero functionality in circuit operation - the active terminals remain only Terminal 1 (cathode) and Terminal 2 (anode).