The MAX856-MAX859 are high-efficiency CMOS step-up DC-DC switching regulators for small low input voltage or battery-powered systems. They combine ultra-low quiescent supply current and high efficiency to give maximum battery life. The MAX856-MAX859 also feature an internal MOSFET power transistor, allowing for high switching frequencies, and have internally set peak inductor current limits, enabling the use of small low-cost inductors.
The MAX856‑MAX859 family are high‑efficiency, CMOS step‑up DC‑DC switching regulators designed for low‑input‑voltage or battery‑powered systems. Fixed‑output versions provide 3.3 V or 5 V, while adjustable versions cover 2.7 V to 6 V.
Key features include typical efficiencies above 85 %, ultra‑low quiescent current (25 µA typical, 1 µA in shutdown), peak‑inductor current limits of 500 mA (MAX856/857) or 125 mA (MAX858/859), and switching frequencies up to 500 kHz. The devices are offered in 8‑SO, µMAX and CERDIP packages.
| Input voltage range (fixed versions) | 0.8 V to VOUT |
|---|---|
| Input voltage range (adjustable versions) | 0.8 V to 6.0 V |
| Output voltage options | 3.3 V or 5 V fixed; 2.7 V‑6.0 V adjustable |
| Typical efficiency | >85 % |
| Quiescent supply current (normal) | 25 µA |
| Quiescent supply current (shutdown) | 1 µA |
| Peak inductor current limit | 500 mA (MAX856/857), 125 mA (MAX858/859) |
| Maximum switching frequency | up to 500 kHz |
Typical efficiencies are greater than 85 %.
The shutdown quiescent current is 1 µA.
The MAX856 has a 500 mA peak‑inductor current limit.