My Inquiry
My Account
Microchip Technology CD821
- Part No.:
- CD821
- Manufacturer:
- Microchip Technology
- Category:
- Single Zener Diodes
- Package:
- Die
- Datasheet:
-
CD821.pdf
- Description:
- DIODE ZENER 6.2V DIE
- Quantity:
- Payment:
- Shipping:
Inventory:9,966
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
CD821 from Microsemi is a monolithic temperature-compensated zener reference die with nominal zener voltage 5.9–6.5 V, tested at 7.5 mA, zener impedance 15 Ω, and voltage temperature stability of ±96 mV over –55°C to +100°C - used as precision voltage reference in high-reliability analog power supply monitoring circuits.
For engineers reviewing the CD821 datasheet, CD821 pinout, CD821 application, or CD821 equivalent, key selection criteria include its MIL-PRF-19500/159 qualification, ±0.01 %/°C effective temperature coefficient, 2 μA reverse leakage at 3 V, and die-level form factor requiring wire bonding for integration into hybrid or hermetic modules.
Technical Context
The CD821 is a bare silicon die (not packaged) with cathode and anode metallized aluminum terminals plus a non-functional test pad; it requires backside electrical isolation and is incompatible with solder reflow due to Au/Al metallization constraints.
Its zener impedance is measured using 10% 60 Hz AC superimposed on 7.5 mA DC test current per Note 1, and its ±96 mV voltage drift over –55°C to +100°C satisfies JEDEC Standard No. 5 for temperature-stable references.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage | 5.9–6.5 V at 7.5 mA - defines stable reference output range under nominal bias |
| Zener Impedance | 15 Ω - low dynamic resistance ensures minimal output voltage variation under load transients |
| Voltage Temp Stability | ±96 mV over –55°C to +100°C - guarantees bounded drift without external compensation |
| Temp Coefficient | ±0.01 %/°C - enables predictable, linear drift behavior for calibration-critical systems |
| Reverse Leakage | 2 μA @ 3 V, 25°C - confirms low parasitic conduction in off-state reference hold applications |
| Operating Temp | –65°C to +175°C - supports deployment in aerospace, downhole, and military environments |
Pinout & Package
CD821 is supplied as a bare die in JANHC-qualified chip form, with 0.010 inch ±0.002 inch thickness, Al-metallized top surface (cathode and anode), and Au back metallization. Backside must be electrically isolated.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (Top Metallization) | Cathode | Must be biased positive relative to anode for zener operation; primary current entry point |
| 2 (Top Metallization) | Anode | Reference ground node; current exit path during zener conduction |
| 3 (Top Metallization) | Test Pad | No electrical function; used only for wire bond process evaluation - not connected in circuit |
Key Features
| Feature | Design Value |
|---|---|
| Monolithic temp-compensated structure | Integrates temperature-sensing and correction elements on single die - eliminates discrete compensation networks |
| Silicon dioxide junction protection | Prevents contamination and moisture ingress at PN junction - critical for long-term parametric stability |
| JANHC/JANKC qualification | Meets MIL-PRF-19500/159 screening - required for defense and space-grade hybrid assemblies |
| Wire-bond compatible metallization | Al top / Au back stack supports thermosonic and ultrasonic bonding - avoids intermetallic formation |
Applications
| Avionics Power Monitoring | Downhole Sensor Conditioning |
|---|---|
Use Scenario: Real-time regulation and fault detection in 28 V DC aircraft bus converters. IC Role / Device Role / Timing Role: Precision voltage reference for ADC reference input and comparator threshold setting. Use Value: ±96 mV drift over –55°C to +100°C ensures consistent trip points across flight envelope without recalibration. | Use Scenario: Signal conditioning front-end in oil/gas wellbore pressure transducers operating at 175°C. IC Role / Device Role / Timing Role: Stable bias reference for instrumentation amplifier gain-setting resistors and sensor excitation. Use Value: –65°C to +175°C operating range and MIL-qualified reliability enable uninterrupted operation in extreme thermal gradients. |
| Nuclear Instrumentation | Military Radar Bias Supply |
Use Scenario: High-stability reference in gamma spectrometer pulse-height analyzers exposed to ionizing radiation. IC Role / Device Role / Timing Role: Zener reference for DAC-controlled high-voltage bias generation in PMT bases. Use Value: Silicon dioxide passivation and monolithic construction minimize radiation-induced parameter shift versus discrete alternatives. | Use Scenario: Reference element in pulsed RF transmitter modulator supply feedback loops. IC Role / Device Role / Timing Role: Low-impedance voltage reference for error amplifier in fast-settling switching regulator control loop. Use Value: 15 Ω zener impedance ensures <10 ns transient response to load steps - critical for pulse fidelity. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar zener reference applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| CD821A | Zener impedance reduced to 13 Ω; same voltage range and temp coefficient | Preferred where lower dynamic impedance improves regulation under fast load transients | Select CD821A when tighter output impedance tolerance is required without changing layout or bias conditions |
| 1N821 | Same electrical specs but in DO-35 glass package; no die-level handling or wire bond capability | Used in PCB-mounted discrete designs rather than hybrid microcircuit or multi-chip module integration | Choose 1N821 only for through-hole prototyping or legacy board replacements - not for new hybrid designs |
Compared with CD821A and 1N821, the CD821 offers optimal trade-off between ultra-low temp drift (±0.01 %/°C), MIL-qualified reliability, and die-level integration flexibility - making it uniquely suited for space-constrained, high-temperature hybrid assemblies where wire bonding is mandatory.
Availability
CD821 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 CD821 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 and mixed-signal components for aerospace, defense, and industrial markets.
The CD821 belongs to Microsemi's MIL-qualified monolithic zener reference die family, designed specifically for integration into hybrid microcircuits and hermetically sealed modules demanding extreme temperature stability and radiation hardness.
FAQ
What is the exact zener voltage tolerance of CD821 at 7.5 mA?
The CD821 has a specified zener voltage range of 5.9 V to 6.5 V when tested at 7.5 mA, representing a ±5.2% tolerance band centered near 6.2 V. This range is guaranteed per LDS-0052 Rev. 1 and applies to all JANHC-qualified CD821 units. The CD821 does not specify a tighter typical value - design margins must accommodate the full 5.9–6.5 V span.
Can CD821 be mounted using solder reflow?
No, CD821 cannot be mounted using solder reflow. Its metallization stack (Al top / Au back) is incompatible with solder reflow processes due to intermetallic formation risk and thermal stress on the bare die. The datasheet explicitly states compatibility only with wire bonding and die-attach techniques excluding solder reflow. Use conductive epoxy or thermosonic bonding instead for CD821 integration.
Is CD821 electrically identical to 1N821?
Yes, CD821 is electrically equivalent to 1N821 per the datasheet: both share identical zener voltage (5.9–6.5 V), test current (7.5 mA), impedance (15 Ω), and temperature coefficient (±0.01 %/°C). However, CD821 is a bare die while 1N821 is a DO-35 packaged device - their form factors, mounting methods, and reliability screening differ significantly.
What is the purpose of the third metallized pad on CD821?
The third metallized pad on CD821 is a test pad intended solely for wire bond process evaluation during manufacturing. It has no electrical connection to the zener junction and must not be bonded or connected in the final circuit. The CD821 functions correctly using only the cathode (Pad 1) and anode (Pad 2); connecting the test pad risks unintended parasitic paths or mechanical damage.
Does CD821 require backside electrical isolation?
Yes, CD821 requires electrically isolated mounting - its gold back metallization must not contact any conductive surface. The datasheet mandates backside isolation to prevent leakage paths and ensure stable zener voltage performance. Failure to isolate the backside may cause increased reverse leakage, voltage drift, or catastrophic failure under bias. Mount CD821 on ceramic or polyimide-insulated substrates with conductive epoxy.
CD821 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- Die
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Voltage - Zener (Nom) (Vz):
- 6.2 V
- Tolerance:
- ±4.83%
- Power - Max:
- -
- Impedance (Max) (Zzt):
- 15 Ohms
- Current - Reverse Leakage @ Vr:
- 2 µA @ 3 V
- Voltage - Forward (Vf) (Max) @ If:
- -
- Operating Temperature:
- -65°C ~ 175°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- Die
CD821 FAQ
1.How can I place an order for CD821 through Aetrix?
Please submit a Request for Quotation (RFQ) for CD821 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for CD821 reliable?
The price and inventory of CD821 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for CD821 is usually 5 days.
3.What payment methods are accepted for CD821?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for CD821 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for CD821?
CD821 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your CD821 order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for CD821?
For technical support, including CD821 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your CD821 requirements.
6.How does Aetrix verify that CD821 is sourced from the original manufacturer or authorized distributors?
All CD821 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that CD821 meets industry standards.
7.What is the process for return or replacement of CD821?
All CD821 units undergo pre-shipment inspection (PSI). If there is an issue with CD821, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The CD821 part is unused and in its original packaging.
Return procedure for CD821:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
CD821 Tags
-
MMBZ5240B-7-F
Diodes Incorporated
-
BZT52C5V6T-7
Diodes Incorporated
-
MMSZ5231B-7-F
Diodes Incorporated
-
BZT52C15-7-F
Diodes Incorporated
-
BZX84C3V3LT1G
onsemi
-
MMSZ5245BS-7-F
Diodes Incorporated
-
MMSZ4682T1G
onsemi
-
BZT52C15S-7-F
Diodes Incorporated
-
MM5Z5V1ST1G
onsemi
-
SMAJ4744A-TP
Micro Commercial Co
-
BZT52C3V6LP-7
Diodes Incorporated
-
SMAZ12-13-F
Diodes Incorporated
Tech Hub
TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
