MAXIM MAX3221EAE+T

The MAX3221/MAX3223/MAX3243 achieve 1µA supply current with Maxim’s revolutionary AutoShutdown™ feature. When the MAX3221/MAX3223/MAX3243 do not sense a valid signal level on their receiver inputs, the on-board power supply and drivers shut down. This occurs if the RS-232 cable is disconnected or if the transmitters of the connected peripheral are turned off. The system turns on again when a valid level is applied to any RS-232 receiver input. The MAX3221/MAX3223/MAX3243 require only 0.1µF capacitors in 3.3V operation, and can operate from input voltages ranging from +3.0V to +5.5V. A proprietary, high-efficiency, dual charge-pump power supply and a low-dropout transmitter combine to deliver true RS-232 performance from a single +3.0V to +5.5V supply. The MAX3221 is a 1-driver/1-receiver 16-pin SSOP version of the 20-pin 2-driver/2-receiver MAX3223. The MAX3243 is a 3-driver/5-receiver with a complementary always-active receiver for external monitoring in a variety of 28 pin packages. The MAX3221/MAX3223/MAX3243’s internal power supply consists of a regulated dual charge pump that provides output voltages of +5.5V (doubling charge pump) and -5.5V (inverting charge pump), regardless of the input voltage (VCC) over the +3.0V to +5.5V range. The charge pumps operate in a discontinuous mode: if the output voltages are less than 5.5V, the charge pumps are enabled; if the output voltages exceed 5.5V, the charge pumps are disabled. Each charge pump requires a flying capacitor (C1, C2) and a reservoir capacitor (C3, C4) to generate the V+ and V- supplies.

• Integrated Charge Pump Circuitry Simplifies Power Requirements
• Eliminates the Need for a±12 Supply
• Operation From a Single +3.3V or +5V Supply
• 1µA Supply Current in Shutdown Mode Saves Power
• AutoShutdown Feature is Enabled After No Activity on Receiver Inputs for 30µs
• Software Control Option for Shutdown

• Battery-Powered Equipment
• Hand-Held Equipment
• Peripherals
• Portable Diagnostics Equipment