MAX328/MA329 are monolithic CMOS analog multi-plexers. The MAX328 is a single-ended, 1-of-8 device, and the MAX329 is a differential, 2-of-8 device. Designed to provide the lowest possible on- and off- leakages, these multiplexers switch signals from high source impedance, providing the mux operates into a high-input-impedance op amp or A/D converter. The MAX328/MAX329 are pin-for-pin replacements for the popular DG508/DG509 in these applications. Adding an external 40kΩ resistor to each input makes the MAX328/MAX329 an excellent fault-tolerant multi- plexer. Low leakage (less than 1pA at +25°C) and 2.5kΩ on-resistance allow the circuit to sustain 110V AC faults indefinitely while maintaining an error of less than 40nV for normal signals (i.e., 1pA times 40kΩ). The MAX328/MAX329 work equally well with a single supply of 10V to 30V or dual supplies of ±5V to ±18V. They also perform well with unbalanced combinations of supply voltage, such as +12V and -5V or +5V and -15V. Low power dissipation (1.9mW with ±15V supplies) allows use in portable applications.
The MAX328 is a single‑ended 1‑of‑8 analog multiplexer, while the MAX329 is a differential 2‑of‑8 device. Both are designed for ultra‑low on‑ and off‑leakage (typical 1 pA) and include fault‑tolerant features when used with external resistors. They operate from a single 10 V to 30 V supply or dual supplies of +5 V to +18 V and can withstand 120 V AC fault conditions.
The datasheet provides absolute maximum ratings, electrical characteristics, pin configurations for multiple package types (DIP, SO, QFN, etc.), and typical application circuits. Ordering information and package outlines are also included, with Maxim’s contact details for pricing and delivery.
| On‑Resistance | 2.5 kΩ |
|---|---|
| Leakage Current | 1 pA typ |
| Supply Voltage Range | 10 V–30 V single supply or +5 V–+18 V dual supplies |
| Power Dissipation | 1.9 mW at +15 V |
| Switching Speed | < 1.5 µs |
| Package (example) | 16‑Pin Plastic DIP (MAX328CPE) |
Both devices have ultra‑low off‑ and on‑leakage of about 1 pA typical.
They can run from a single 10 V to 30 V supply or from dual supplies of +5 V to +18 V.
Yes, they are pin‑for‑pin replacements for the DG508/DG509 devices.
The typical on‑resistance is about 2.5 kΩ.