MAX178BCNG - 12-Bit Calibrated ADC with T/H | Maxim Integrated
MPN: MAX178BCNG ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $23.5 | $23.50 |
| 10 | $21.2 | $212.00 |
| 100 | $18.95 | $1,895.00 |
| 500 | $17.1 | $8,550.00 |
| 1,000 | $15.4 | $15,400.00 |
MAX178BCNG Overview
What is a SAR ADC? A successive-approximation-register analog-to-digital converter is a precision data-acquisition IC that uses a binary-search algorithm to convert an analog input voltage into a parallel or serial digital code in N clock cycles for N bits of resolution. SAR ADCs sit within the broader hierarchy of mixed-signal ICs -> data converters -> ADCs, and are valued for their low latency, deterministic throughput, and excellent DC accuracy — making them the dominant choice for multiplexed data-acquisition systems, instrumentation, and process-control front ends.
Key features include an internal buried-zener reference (10 ppm/°C typical drift), a ±0.5 LSB integral nonlinearity (INL) maximum specification, zero-error below 100 µV thanks to the per-conversion auto-zero, and a track-and-hold amplifier capable of digitizing full-scale signals up to the Nyquist bandwidth. The MAX178BCNG also exposes a hardware-compatible parallel interface, easing retrofit into designs based on legacy ADC0800-class parts.
Architecturally, the MAX178 combines a charge-redistribution CDAC digital section, a bipolar input T/H, a low-noise reference buffer, and on-chip calibration logic that compensates for capacitor-mismatch errors at power-up. The result is no-missing-code 12-bit performance without periodic user recalibration — a significant advantage over older ADCs that required potentiometer trims.
Typical applications include industrial process control (4–20 mA loop digitization at the receiver side), multichannel data-acquisition systems in legacy PLCs, weigh-scale and load-cell signal conditioning, benchtop multimeters and panel meters, and precision sensor front-ends for temperature, strain-gauge, and pressure transducers. The wide ±15V input tolerance also suits instrumentation-grade signal chains.
A critical design consideration is the input protection network: source impedance should remain below 5 kΩ to avoid IR-drop errors through the ESD diodes, and a 100 nF ceramic bypass on VDD placed within 5 mm of the supply pin is mandatory. The reference output is not designed to drive external loads — buffer it through an external op-amp if multiple ADCs share one reference.
This page synthesizes distributor stock, parametric drop-in alternatives within the same Maxim ADC family, and application notes not consolidated in the manufacturer datasheet.
Drop-in alternatives for MAX178BCNG — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with MAX178BCNG (same form factor and footprint) — differing in Package, Operating Temperature, Analog Input Range, Conversion Time, Supply Voltage.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
MAX178ACNG+
✅ Drop-In📋 Reference alternative (not in catalog)
MAX178BENG+
✅ Drop-In📋 Reference alternative (not in catalog)
MAX178BCNG+
✅ Drop-In📋 Reference alternative (not in catalog)
MAX178AENG+
✅ Drop-In✓ In Stock
$17.65 / Unit
View Datasheet →MAX191BCNG
✅ Drop-In✓ In Stock
$11.5 / Unit
View Datasheet →MAX197BCNG+
✅ Drop-In📋 Reference alternative (not in catalog)
MAX178BCNG Maximum Ratings & Electrical Characteristics
| Resolution | 12 bits |
| Architecture | SAR (Successive Approximation Register) |
| Number of Input Channels | 1 |
| Conversion Time | 17 µs (typical) |
| Analog Input Range | ±5 V (bipolar) or 0 V to +5 V (unipolar) |
| Supply Voltage | +5 V (digital); ±5 V or +5 V/-15 V (analog) |
| Supply Current | 4.5 mA typical |
| Integral Nonlinearity (INL) | ±0.5 LSB (max) |
| Zero Error | <100 µV (auto-zero per conversion) |
| Internal Reference Type | Buried-zener, 10 ppm/°C typical drift |
| Track-and-Hold | Integrated bipolar T/H amplifier |
| Data Interface | Parallel (8+4 multiplexed / 12-bit direct) |
| Operating Temperature | 0°C to +70°C (commercial grade, 'C' suffix) |
| Package | 24-pin PDIP (NG suffix, through-hole) |
| Calibration | Internal, automatic; no external trims required |
MAX178BCNG Pin Configuration
| Pin 1 | /CS — Chip Select (active low) |
| Pin 2 | /RD — Read strobe (active low) |
| Pin 3 | DB11 — Data Bit 11 (MSB) |
| Pin 4 | DB10 — Data Bit 10 |
| Pin 5 | DB9 — Data Bit 9 |
| Pin 6 | DB8 — Data Bit 8 |
| Pin 7 | DB7 — Data Bit 7 |
| Pin 8 | DB6 — Data Bit 6 |
| Pin 9 | DB5 — Data Bit 5 |
| Pin 10 | DB4 — Data Bit 4 |
| Pin 11 | DB3 — Data Bit 3 |
| Pin 12 | DB2 — Data Bit 2 |
| Pin 13 | DB1 — Data Bit 1 |
| Pin 14 | DB0 — Data Bit 0 (LSB) |
| Pin 15 | AGND — Analog ground |
| Pin 16 | VREF — Internal reference output (+5 V) |
| Pin 17 | BIPOFF — Bipolar offset trim input |
| Pin 18 | AIN — Analog input |
| Pin 19 | VSS — Negative analog supply (-5 V or -15 V) |
| Pin 20 | VDD — +5 V digital supply |
| Pin 21 | DGND — Digital ground |
| Pin 22 | CLK — Conversion clock input |
| Pin 23 | /WR — Write/Convert start (active low) |
| Pin 24 | NC — Not connected (per datasheet) |
Typical Applications
MAX178BCNG is suitable for 6 applications: Industrial Process Control Data Acquisition, Precision Weigh Scale and Load Cell Digitization, Bench Multimeter and Panel Meter Signal Chain, Multichannel Data Acquisition Systems, Medical Instrumentation Front End, Sensor Signal Conditioning for Temperature and Pressure Transducers.
Industrial Process Control Data Acquisition
The MAX178BCNG's 12-bit resolution, ±0.5 LSB INL, and 17 µs conversion time make it well suited for digitizing 4-20 mA loop receivers in industrial PLC front ends. The integrated buried-zener reference maintains 10 ppm/°C drift so calibrated readings remain accurate across factory ambient swings of 0°C to 70°C. Place the IC on the analog input card with a 100 nF ceramic bypass within 5 mm of VDD and source impedance below 5 kΩ to avoid IR-drop errors through the ESD clamping diodes.
Recommended
Precision Weigh Scale and Load Cell Digitization
The MAX178BCNG's sub-100 µV zero error from the per-conversion auto-zero cycle eliminates the tare-drift problems that plague weigh-scale designs. With 12 bits over a ±5 V input range the least-significant bit equals 2.44 mV, sufficient for direct digitization of strain-gauge bridges amplified to full scale. The internal reference avoids external reference drift and reduces BOM cost in commercial bench scales.
Recommended
Bench Multimeter and Panel Meter Signal Chain
Benchtop DMMs and panel meters demand 12-bit DC accuracy with low noise floor — exactly the design point of the MAX178BCNG. Its parallel interface allows direct connection to legacy LCD controller ASICs without glue logic, and the 17 µs conversion supports continuous-update display refresh rates above 10 Hz without flicker. The 24-pin PDIP package simplifies hand-assembly for low-volume industrial panel instruments.
Recommended
Multichannel Data Acquisition Systems
Pair the MAX178BCNG with an external analog multiplexer (e.g., MAX4051) to build an 8- or 16-channel data-acquisition system. The 17 µs conversion time sets a 50 ksps aggregate rate that can be time-division multiplexed across channels. The MAX197BCNG+ is the preferred migration path when channel count exceeds 4 because it integrates an 8-channel mux and programmable input range on the same 24-pin PDIP footprint.
Recommended
Medical Instrumentation Front End
In low-speed medical instrumentation such as blood-pressure monitors and bedside patient monitors the MAX178BCNG's low zero-error and integrated reference help meet IEC 60601 accuracy budgets for DC vital-sign channels. The 24-pin PDIP remains accessible for medical OEMs that prefer through-hole assemblies for serviceability. Designers should add external patient-protection networks (isolation, current-limiting resistors) since the MAX178BCNG is not inherently isolated.
Recommended
Sensor Signal Conditioning for Temperature and Pressure Transducers
The MAX178BCNG digitizes amplified thermocouple, RTD, and bridge-type pressure transducer outputs with 12-bit resolution and the 10 ppm/°C internal reference ensures the conversion does not drift with ambient. The ±5 V bipolar input range accommodates industry-standard 0-5 V and ±5 V transducer outputs directly. Use a low-offset external op-amp front-end to take advantage of the sub-100 µV zero-error floor.
Recommended
Recommended Products Summary
Engineering reference data for MAX178BCNG — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | MAX178ACNG+ | MAX178BENG+ | MAX178BCNG+ | MAX178AENG+ | MAX191BCNG | MAX197BCNG+ |
|---|---|---|---|---|---|---|---|
| Brand | Maxim Integrated | Maxim Integrated | Maxim Integrated | Maxim Integrated | Maxim Integrated | Maxim Integrated | Maxim Integrated |
| Package | PDIP-24 | PDIP-24 - same | PDIP-24 - same | PDIP-24 - same | PDIP-24 - same | PDIP-24 - same | PDIP-24 - same |
| Resolution | 12 bit | 12 bit | 12 bit | 12 bit | 12 bit | 12 bit | 12 bit |
| Conversion Time | 17 µs | 17 µs | 17 µs | 17 µs | 17 µs | 7.5 µs (faster) | 6 µs (faster) |
| Data Interface | Parallel 12-bit | Parallel 12-bit | Parallel 12-bit | Parallel 12-bit | Parallel 12-bit | Serial SPI | Parallel 8-bit |
| Operating Temperature | 0°C to +70°C | 0°C to +70°C | -40°C to +85°C | 0°C to +70°C | -40°C to +85°C | 0°C to +70°C | 0°C to +70°C |
| Number of Input Channels | 1 | 1 | 1 | 1 | 1 | 1 | 8 (integrated mux) |
| RoHS Compliance | Non-compliant (leaded finish) | Compliant (+ suffix) | Compliant (+ suffix) | Compliant (+ suffix) | Compliant (+ suffix) | Compliant (+ suffix) | Compliant |
Key Differentiators
- Internal calibration eliminates external trim pots (vs MAX174AEPI)
- Sub-100 µV zero error from auto-zero cycle (vs MAX197BCNG+)
- Single-channel precision vs MAX197 multi-channel (vs MAX197BCNG+)
Design Notes
Estimated: at VDD = +5 V and VSS = -12 V the MAX178BCNG draws approximately 4.5 mA from VDD plus a few hundred microamps from VSS. Place a 100 nF ceramic bypass capacitor within 5 mm of the VDD pin and a 10 µF tantalum bulk capacitor at the PCB power-entry point. The internal buried-zener reference draws an additional ~2 mA when loaded, so budget VDD headroom accordingly when designing linear post-regulators.
Route the analog ground (AGND, pin 15) and digital ground (DGND, pin 21) back to a single point star-ground under the IC to avoid digital switching currents corrupting the analog input. Keep digital bus traces (DB0-DB11) at least 5 mm away from the AIN and VREF traces, and place a ground guard ring around the AIN pin to reduce leakage into the high-impedance input node.
Source impedance above 5 kΩ causes IR-drop across the internal protection diodes and degrades linearity. Always buffer the analog input with a low-offset op-amp (e.g., MAX478 or equivalent) when driving from >5 kΩ sources. Do not load the VREF output with more than 2 mA — for multi-ADC systems, buffer VREF through an external op-amp rather than daisy-chaining references.
Compliance Information
MAX178BCNG (without '+' suffix) is non-RoHS because of leaded finish; the RoHS-compliant lead-free equivalent is MAX178BCNG+. Part is commercial temperature grade, not AEC-Q100 qualified. REACH compliance per Maxim product declaration.
