MAX1684/MAX1685 are high-efficiency, internal-switch, pulse-width modulation (PWM) step-down switching regulators intended to power cellular phones, communicating PDAs, and handy-terminals. These devices deliver a guaranteed 1A output current from two lithium-ion (Li+) batteries. Their wide-input voltage range of 2.7V to 14V gives design flexibility and allows batteries to charge from a wall cube, since the ICs operate at the higher voltages that occur when the battery is removed. The output voltage is preset to 3.3V or can be externally adjusted from 1.25V to VIN. The low on-resistance power switch and built-in synchronous rectifier provide high efficiencies of up to 96%. There are four modes of operation: fixed-frequency, normal, low-power, and shutdown. The fixed-frequency PWM mode of operation offers excellent noise character- istics. The normal mode maintains high efficiency at all loads. The low-power mode is used to conserve power in standby or when full load is not required. The shutdown mode is used to power down the device for minimal cur- rent draw. The MAX1684 runs at 300kHz for applications that require highest efficiency. The MAX1685 runs at 600kHz to allow the use of smaller external compo- nents. These devices can also be synchronized to an external clock. Other features include a 100% duty cycle for low-dropout applications, an auxiliary 3V/5mA output, and a 1% accurate reference. Both devices are available in a space-saving 16-pin TSSOP package.
The MAX1684 and MAX1685 are high‑efficiency, internal‑switch, PWM step‑down regulators designed for cellular phones, PDAs, and other portable devices. They provide up to 1 A output current from a wide input range of 2.7 V to 14 V and support adjustable output voltages.
Key performance figures include up to 96 % efficiency, fixed‑frequency PWM operation at 300 kHz (MAX1684) or 600 kHz (MAX1685), and operation in four modes (fixed‑frequency, normal, low‑power, shutdown). The devices are offered in a compact 16‑QSOP package and feature low quiescent currents for standby operation.
| Input Voltage Range | 2.7 V to 14 V |
|---|---|
| Output Current Capability | 1 A |
| Maximum Efficiency | up to 96 % |
| Package | 16‑QSOP |
| Low‑Power Mode Quiescent Current | 25 µA |
| Shutdown Current | 2 µA |
The devices operate from 2.7 V up to 14 V input.
They can achieve up to 96 % efficiency.
Both are available in a 16‑QSOP package.