BA728N - Dual Op-Amp, 3-18V, Single Supply | ROHM
MPN: BA728N ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $0.85 | $0.85 |
| 10 | $0.72 | $7.20 |
| 100 | $0.58 | $58.00 |
| 500 | $0.49 | $245.00 |
| 1,000 | $0.42 | $420.00 |
BA728N Overview
What is a dual operational amplifier? A dual operational amplifier (dual op-amp) is an integrated circuit that combines two independent op-amp channels in a single package, sharing only the power and ground pins. Dual op-amps belong to the linear IC family, which itself sits within the broader category of analog signal-conditioning semiconductors. They are fundamental to almost every analog PCB, providing gain, buffering, filtering, and comparison functions at low cost and low power.
Key features of the BA728N include: a single-supply operating voltage of 3V to 18V (or dual ±1.5V to ±9V), low power consumption typical of the BA728 family, pin configuration identical to the industry-standard 8-pin general-purpose op-amp outline, internal phase compensation (no external compensation capacitor required), and high common-mode input range that includes the negative supply rail when used in single-supply mode.
The internal architecture is a classic bipolar transistor design with on-chip frequency compensation, eliminating the need for external compensation capacitors. This makes the BA728N a true drop-in functional equivalent to legacy 8-pin dual op-amps such as the LM358 / NJM4558 / BA4558 family, with the same DC characteristics but at a lower quiescent current and with ROHM's signature wide single-supply range.
Typical applications include active filters, transducer signal conditioning, comparator circuits, DC gain blocks, audio pre-amplifiers, and general-purpose analog signal chains in consumer, industrial, and hobby electronics. Its pin-compatibility with the BA728 / BA728F variants (which differ only in mechanical package) allows designers to substitute across mechanical configurations without PCB changes.
When designing with the BA728N, observe the absolute maximum supply rating of 18V (single supply) or ±9V (dual supply), place a 0.1 µF decoupling capacitor close to VCC+ pin, and avoid output short circuits to ground or either rail. The exposed lead frame (SIP package) limits mounting to through-hole assemblies only.
This page synthesizes datasheet specifications, distributor pricing (as of 2026-10-05), pin-compatible alternatives, and practical design notes to help engineers select and apply this dual operational amplifier.
Drop-in alternatives for BA728N — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
BA4558N
✅ Drop-In📋 Reference alternative (not in catalog)
LM358N
✅ Drop-In📋 Reference alternative (not in catalog)
LM2904N
✅ Drop-In📋 Reference alternative (not in catalog)
NJM4558D
✅ Drop-In📋 Reference alternative (not in catalog)
BA10358N
✅ Drop-In📋 Reference alternative (not in catalog)
BA728N Maximum Ratings & Electrical Characteristics
| Manufacturer | ROHM Semiconductor |
| Part Number | BA728N |
| Function | Dual operational amplifier |
| Number of Channels | 2 |
| Internal Phase Compensation | Yes (built-in) |
| Single-Supply Voltage Range | 3 V to 18 V |
| Dual-Supply Voltage Range | ±1.5 V to ±9 V |
| Common-Mode Input Range | Includes negative rail (single supply mode) |
| Package Type | SIP-8 (Single In-line Package, 8-pin) |
| Pin Configuration | Industry-standard 8-pin dual op-amp |
| Low Power Consumption | Yes |
| Mounting Type | Through-Hole (SIP) |
| RoHS Status | Compliant |
| Lead-Free | Yes (per ROHM product line convention) |
| Datasheet Document Pages | 4 pages (per alldatasheet.com) |
BA728N Pin Configuration
| Pin 1 | OUTPUT A — Op-amp A output |
| Pin 2 | INVERTING INPUT A — Op-amp A inverting input |
| Pin 3 | NON-INVERTING INPUT A — Op-amp A non-inverting input |
| Pin 4 | VCC- — Negative supply / Ground (single supply) |
| Pin 5 | NON-INVERTING INPUT B — Op-amp B non-inverting input |
| Pin 6 | INVERTING INPUT B — Op-amp B inverting input |
| Pin 7 | OUTPUT B — Op-amp B output |
| Pin 8 | VCC+ — Positive supply |
Typical Applications
BA728N is suitable for 6 applications: Active Audio Filter Circuits, Transducer Signal Conditioning, Window Comparator Circuits, DC Gain Blocks for Instrumentation, Hobby Electronics and Educational Kits, Legacy Equipment Repair and Replacement.
Active Audio Filter Circuits
The BA728N's built-in phase compensation and wide single-supply range (3V to 18V) make it well-suited to active audio filter circuits such as Sallen-Key low-pass and high-pass topologies. Its dual-channel integration allows both filter poles of a 2nd-order filter to be implemented with a single IC, reducing PCB area. Compared to uncompensated op-amps, the BA728N eliminates external compensation capacitors, simplifying PCB layout in stompbox and consumer audio designs where its SIP-8 through-hole form factor is preferred.
Recommended
Transducer Signal Conditioning
The BA728N is commonly deployed as a signal-conditioning front-end for transducers such as thermistors, photodiodes, and strain gauges. Its input common-mode range includes the negative rail when operated from a single 5V to 12V supply, allowing direct connection to ground-referenced sensor bridges without level shifting. With both channels internally compensated, designers can implement a differential amplifier plus gain stage with a single BA728N IC, simplifying BOM and saving PCB space in industrial sensor modules.
Recommended
Window Comparator Circuits
Window comparators monitor an input signal to detect excursions above and below defined thresholds, commonly used in battery voltage monitoring, sensor fault detection, and over/under-speed detection. The BA728N's two internally compensated op-amps can implement a complete window comparator (two comparators plus a reference buffer) in a single SIP-8 package. Operated from a single 5V to 15V rail, the BA728N can compare input signals from 0V to VCC-1.5V with no level shifting required.
Recommended
DC Gain Blocks for Instrumentation
DC-coupled gain stages require op-amps with low offset and stable DC performance; the BA728N provides standard bipolar DC characteristics suitable for non-precision instrumentation such as panel meters and process-indicator displays. Its dual integration supports two independent gain channels (e.g., voltage and current measurement paths) on a single 8-pin footprint. Designers should note that the BA728N is a general-purpose part, not a precision op-amp; for sub-mV offset applications consider a precision alternative.
Recommended
Hobby Electronics and Educational Kits
The BA728N's SIP-8 through-hole package makes it a favorite in hobby electronics, educational lab kits, and through-hole soldering tutorials. Its industry-standard pinout mirrors the LM358 and BA4558, so students can swap between parts to compare datasheets and learn about op-amp behavior. Operated from a 9V battery via single supply, the BA728N can drive LED bar-graph indicators, audio amplifiers, and oscillator circuits across a 3V to 18V range without external regulators.
Recommended
Legacy Equipment Repair and Replacement
Vintage consumer electronics, industrial controllers, and audio equipment often rely on SIP-8 dual op-amps that are now obsolete. The BA728N's continued active production status and identical 8-pin SIP pinout make it a service-friendly replacement for legacy BA728 / BA4558 / NJM4558 sockets. Restoration technicians can stock the BA728N as a universal SIP-8 dual op-amp spare, with the 3V to 18V supply range covering virtually all vintage analog rails (5V, 9V, 12V, 15V, 18V).
Recommended
Recommended Products Summary
Engineering reference data for BA728N — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | BA728F | BA4558N | BA10358N | LM358N | LM2904N | NJM4558D |
|---|---|---|---|---|---|---|---|
| Brand | ROHM Semiconductor | ROHM Semiconductor | ROHM Semiconductor | ROHM Semiconductor | Texas Instruments | Texas Instruments | NJR |
| Package | SIP-8 (through-hole) | SOP-8 (SMD) - different footprint | SIP-8 - same footprint | SIP-8 - same footprint | PDIP-8 - functionally same pinout | PDIP-8 - functionally same pinout | DIP-8 - functionally same pinout |
| Number of Channels | 2 | 2 | 2 | 2 | 2 | 2 | 2 |
| Dual-Supply Range | ±1.5V to ±9V | ±1.5V to ±9V | ±18V | ±18V | ±1.5V to ±16V | ±1.5V to ±13V | ±18V |
| Internal Phase Compensation | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
| Common-Mode to V- | Yes (single supply) | Yes (single supply) | No (dual supply) | Yes | Yes | Yes | No (dual supply) |
| Mounting Type | Through-Hole (SIP) | Surface Mount (SOP) | Through-Hole (SIP) | Through-Hole (SIP) | Through-Hole (PDIP) | Through-Hole (PDIP) | Through-Hole (DIP) |
| Automotive Grade | No | No | No | No | No | Yes (AEC-Q100) | No |
Key Differentiators
- SIP-8 through-hole variant of the BA728 family (vs BA728F)
- Wide single-supply voltage range up to 18V (vs NJM4558D)
- Includes negative rail in common-mode input range (vs BA4558N)
Design Notes
Decouple the BA728N supply pins (VCC+ pin 8 and VCC- pin 4) with a 0.1 µF ceramic capacitor placed within 5 mm of the package, plus a 10 µF electrolytic bulk capacitor on the same rail. Single-supply operation requires only pin 4 tied to ground; dual-supply operation requires both rails to be referenced. Do not exceed the absolute maximum supply rating of 18V (single) or ±9V (dual) - transients above these levels can permanently damage the IC.
The SIP-8 single in-line package requires through-hole PCB assembly and a single-row 8-hole land pattern with 2.54 mm (0.1 inch) pin pitch. For SIP-8, allow at least 3 mm of clearance on each side of the package body for solder fillet formation and inspection. If converting a SIP-8 design to surface-mount, use the BA728F (SOP-8 variant) on an SOIC-8 land pattern - do not attempt to bend SIP leads for SMT retrofit.
The BA728N's input common-mode range includes the negative supply rail when operated in single-supply mode, allowing direct sensing of ground-referenced signals without level shifting. However, the upper common-mode limit is typically VCC-1.5V; inputs approaching VCC may saturate the input stage. For rail-to-rail input requirements, consider the BA10358N family. Avoid routing high-impedance input traces near switching nodes - the BA728N's standard bipolar input stage has moderate input bias current and is susceptible to EMI pickup.
Do not assume the BA728N is a precision op-amp - it is a general-purpose bipolar part with typical input offset voltage in the millivolt range and unspecified drift characteristics. For precision instrumentation requiring sub-mV offset or low drift, substitute a dedicated precision op-amp. Also avoid shorting the output to either supply rail; the BA728N has output short-circuit protection only to ground, and sustained shorts to VCC+ can cause thermal failure. Always check the load impedance - the BA728N can drive 2 kΩ loads to within a few volts of the rails but cannot drive low-impedance headphones directly.
Compliance Information
RoHS and REACH compliance inferred from ROHM product line convention. Halogen-free status not explicitly stated in available web data. AEC-Q100 not applicable - standard commercial/industrial grade part. Choose LM2904N for automotive-grade equivalent.
