CA3420AE - BiMOS Op-Amp, 0.5MHz, Low-V, pA Input | Renesas
Référence : CA3420AE ✓ Actif| Qté | Prix unitaire | Total |
|---|---|---|
| 1 | $2.85 | $2,85 |
| 10 | $2.55 | $25,50 |
| 100 | $2.1 | $210,00 |
| 500 | $1.75 | $875,00 |
| 1 000 | $1.45 | $1 450,00 |
CA3420AE Présentation
What is a BiMOS operational amplifier? A BiMOS op-amp is a hybrid analog integrated circuit that combines the high input impedance and ultra-low input current of PMOS transistors with the strong drive capability and DC precision of bipolar transistors. This places the BiMOS family in the broader taxonomy: operational amplifier -> amplifier IC -> linear IC -> analog signal chain -> semiconductor. Compared with a pure bipolar op-amp, a BiMOS part offers several picoamperes of input bias (rather than nanoamperes), and compared with a CMOS op-amp, a BiMOS part typically delivers higher output drive and better DC accuracy.
Key features include 0.5 MHz unity-gain bandwidth, internal phase compensation for unity-gain stability, a unique bootstrapped guardbanding network that minimizes leakage, and rail-to-rail-ground sensing on the low side. The PMOS input pair gives the CA3420AE an input impedance exceeding 1 Tohm, and the bipolar output stage can swing within millivolts of ground while sinking several milliamps - a useful trait when the supply is only a few volts and headroom is at a premium.
The CA3420AE is internally compensated and designed to operate from a single 2 V to 15 V supply (or dual ±1 V to ±7.5 V), making it compatible with low-voltage battery and legacy ±5 V analog rails. The bipolar output stage, combined with the PMOS input pair, gives the part its distinctive low-input-current / moderate-drive profile.
Typical applications include pH and ion-selective electrode buffers, photodiode transimpedance preamps, precision long-time-constant integrators, sample-and-hold circuits, and high-impedance sensor signal conditioning. The wide supply range and single-supply ground-sensing capability make it a strong fit for battery-powered instrumentation as well as industrial process-control front ends.
When designing with the CA3420AE, observe that the bipolar output stage cannot swing fully to the positive rail - typically leaving roughly 1 V of headroom - so design the surrounding circuit with appropriate margin. Input traces should be guarded to fully realize the 1 pA input bias advantage; unterminated high-impedance nodes will pick up 50/60 Hz hum and any nearby leakage.
This page synthesizes Renesas datasheet specifications, distributor pricing snapshots, and pin-compatible cross references for engineers evaluating the CA3420AE for low-leakage precision analog front ends.
Alternatives de remplacement direct pour CA3420AE — même boîtier, compatible broche à broche. Les références à boîtier différent nécessitant une retouche du PCB sont exclues.
Variantes de cette série
Modèles de la même série directement compatibles avec CA3420AE (même facteur de forme et même empreinte) — différant par Gain Bandwidth Product, Mounting Type, Product Type.
Outil de comparaison rapide — sélectionnez des références alternatives pour une comparaison côte à côte :
CA3420E
✅ Remplacement direct✓ En stock
$3.25 / unité
Voir la fiche technique →CA3420AMZ
✅ Remplacement direct📋 Alternative de référence (hors catalogue)
CA3140AE
✅ Remplacement direct📋 Alternative de référence (hors catalogue)
CA3140AMZ
✅ Remplacement direct📋 Alternative de référence (hors catalogue)
LM358N
✅ Remplacement direct📋 Alternative de référence (hors catalogue)
CA3420AE Valeurs maximales et caractéristiques électriques
| Product Type | Operational Amplifier |
| Architecture | BiMOS (PMOS input + Bipolar output) |
| Number of Channels | 1 |
| Gain Bandwidth Product | 0.5 MHz |
| Input Bias Current (typical) | < 1 pA |
| Input Impedance | > 1 Tohm |
| Supply Voltage Range (single) | 2 V to 15 V |
| Supply Voltage Range (dual) | ±1 V to ±7.5 V |
| Output Swing (low side) | Near ground (mV above GND) |
| Plage de température de fonctionnement | -40C to +85C (industrial) |
| Boîtier | 8-pin PDIP (E suffix) |
| Type de montage | Through-Hole |
| Compliance | RoHS - depends on date code (legacy part) |
Configuration des broches de CA3420AE
| Broche 1 | OFFSET NULL — Offset trim pin 1 (typically left open or 10 kohm pot to OFFSET NULL 2) |
| Broche 2 | IN- — Inverting input |
| Broche 3 | IN+ — Non-inverting input |
| Broche 4 | V- — Negative supply (or GND for single-supply operation) |
| Broche 5 | OFFSET NULL — Offset trim pin 2 |
| Broche 6 | OUTPUT — Amplifier output |
| Broche 7 | V+ — Positive supply |
| Broche 8 | NC — Not connected (per datasheet) |
Applications typiques
CA3420AE convient pour 6 applications: pH / Ion-Selective Electrode Buffer, Photodiode Transimpedance Preamplifier, Long-Time-Constant Integrator, High-Impedance Sensor Signal Conditioning, Battery-Powered Instrumentation Front End, Sample-and-Hold Circuit.
pH / Ion-Selective Electrode Buffer
The CA3420AE's sub-1 pA input bias and >1 Tohm input impedance make it a textbook front end for high-source-impedance electrodes. Placed as a voltage follower between the probe and an ADC, the op-amp preserves the small electrochemical voltage (tens of millivolts) without drawing appreciable current from the electrode, which would otherwise polarize it and introduce drift. Trade-off: the 0.5 MHz GBW limits the buffer to slow process-control loops rather than fast analytical instrumentation.
Recommandé
Photodiode Transimpedance Preamplifier
In a photodiode TIA, the CA3420AE converts the photodiode's pA-to-uA photocurrent into a usable voltage via a feedback resistor. The PMOS input stage's sub-picoampere bias keeps the dark-current error negligible, while the bipolar output stage sinks the feedback current and swings within millivolts of ground for single-supply operation. This combination is widely used in medical pulse oximeters and industrial smoke detectors where ambient light rejection at the analog front end is critical.
Recommandé
Long-Time-Constant Integrator
The CA3420AE is a classic integrator op-amp for sample-and-hold, charge-amplifying piezo sensor front ends, and analog computation. Its PMOS input keeps the integrator's hold capacitor from being discharged by input bias current, extending hold times to seconds or minutes - essential for peak-detect and slow-event capture circuits. The bipolar output can drive subsequent gain stages or ADCs with millivolts of ground-sensing accuracy, simplifying single-rail 5 V designs.
Recommandé
High-Impedance Sensor Signal Conditioning
Used as the first stage after a piezoelectric sensor, humidity sensor, or other high-Z transducer, the CA3420AE preserves signal fidelity that a bipolar op-amp would corrupt with nanoampere-class bias current. According to the Renesas datasheet, the unique guardbanding network further reduces leakage paths, supporting >1 Tohm effective input impedance on a properly guarded PCB. This makes the part a strong fit for vibration, acoustic, and weigh-scale front ends.
Recommandé
Battery-Powered Instrumentation Front End
Operating from a single 2 V to 15 V supply, the CA3420AE is ideal for portable, battery-powered instrumentation including handheld pH meters, medical monitors, and field data loggers. Its modest 0.5 MHz bandwidth and millivolt-level ground-sensing capability let designers run the entire analog chain from a single lithium cell with predictable headroom. The 8-pin PDIP also simplifies hand-soldered prototypes and field repairs.
Recommandé
Sample-and-Hold Circuit
In a sample-and-hold, the CA3420AE drives the hold capacitor while a low-leakage analog switch disconnects the input; its sub-picoampere input bias and bipolar output stage combine to give long hold times with low droop. According to Renesas datasheet figures, the BiMOS architecture delivers hold-time performance that pure-CMOS op-amps struggle to match in low-voltage single-supply designs. Typical uses include successive-approximation ADC input buffers and peak detectors in test equipment.
Recommandé
Récapitulatif des produits recommandés
Données de référence d'ingénierie pour CA3420AE — comparaison, recommandations de conception et informations de conformité.
Guide de sélection
Comparaison avec les alternatives
| Paramètre | Ce produit | CA3420E | CA3420AMZ | CA3140AE | CA3140AMZ | LM358N |
|---|---|---|---|---|---|---|
| Package | PDIP-8 | PDIP-8 - same | SOIC-8 - same pin count, surface-mount | PDIP-8 - same | SOIC-8 - same | PDIP-8 - same (dual op-amp) |
| Brand | Renesas Electronics | Renesas Electronics | Renesas Electronics | Renesas Electronics | Renesas Electronics | Texas Instruments |
| Architecture | BiMOS (PMOS input + Bipolar output) | BiMOS (PMOS input + Bipolar output) - same | BiMOS (PMOS input + Bipolar output) - same | BiMOS (MOSFET input + Bipolar output) | BiMOS (MOSFET input + Bipolar output) | Bipolar (BJT input) |
| Gain Bandwidth Product | 0.5 MHz | 0.5 MHz | 0.5 MHz | 4.5 MHz | 4.5 MHz | 1 MHz (per channel) |
| Input Bias Current (typ) | < 1 pA | < 1 pA | < 1 pA | ~10 pA | ~10 pA | ~45 nA |
| Single Supply Voltage Range | 2 V to 15 V | 2 V to 15 V | 2 V to 15 V | 4 V to 36 V | 4 V to 36 V | 3 V to 32 V |
| Number of Channels | 1 | 1 | 1 | 1 | 1 | 2 (dual) |
| Offset Grade | A grade (enhanced) | Standard | A grade | A grade | A grade | N/A |
| Pin-to-Pin Compatible | Reference | Yes | Yes (SOIC-8 vs PDIP-8) | Yes (same PDIP-8, different pin 1/5/8 usage) | Yes (SOIC-8) | Pin-compatible package, dual op-amp pinout |
Principaux différenciateurs
- Sub-picoampere input bias with single-supply ground-sensing output (vs LM358N)
- Lower minimum supply voltage (2 V vs 4 V) (vs CA3140AE)
- Standard-grade drop-in option available in same package (vs CA3420E)
Notes de conception
Guard the high-impedance input traces with a driven ring tied to the same potential as the input (or to the op-amp output if in follower configuration). Without guarding, PCB surface leakage at high humidity will dominate the CA3420AE's <1 pA input bias, defeating the main advantage of the part. Use a PTFE or ceramic substrate if possible, and avoid solder flux residue near the input node.
Decouple V+ (pin 7) with a 0.1 uF ceramic capacitor placed within 5 mm of the pin, and add a 10 uF tantalum or ceramic bypass on the supply rail. The CA3420AE is internally compensated, so no compensation capacitor is needed, but the bipolar output stage draws brief current spikes during load transitions that must be supplied locally. Estimated: at 5 V single rail the part draws a few hundred microamps quiescent, so the 0.1 uF bypass is sufficient for normal sensor loads.
Do not assume the CA3420AE swings rail-to-rail. The bipolar output stage cannot reach V+, so leave at least 1 V of headroom (typically more) between the desired output swing and V+; the low side swings within millivolts of V-. Choosing V+ too close to the desired output is the most common CA3420 design mistake, especially when migrating from a CMOS op-amp.
Informations de conformité
CA3420AE is a mature Renesas/Intersil part with date-code-dependent RoHS compliance. Verify the date code with the manufacturer or distributor before using in RoHS-strict designs. AEC-Q100 qualification not applicable for this through-hole industrial-grade op-amp.
