Datasheet AS1720 Solenoid / Valve Driver with Current Limitation 1 General Description 2 Key Features Supply Range: +5V to +50V The AS1720A is a low side current source providing an optimized DC Operation for power saving and ultra low electromagnetic Internal VDDA: 3.3V radiation. Supply Current: 1 mA The AS1720B is a low side switch providing a PWM output, which Internal osc frequency: 30kHz frequency is defined by an internal RC oscillator. The adjustable Fix delay: 136ms PWM allows a fine control of the power delivered to the load. Adjustable duty cycle: 20% 90% (AS1720B only) Table 1. Standard Products Adjustable energizing current: 10mA 100mA Model Operation Mode Adjustable hold current: 30% - 70% of energizing current AS1720A DC Current Source Operation Current Limitation AS1720B PWM Switching Operation Thermal shutdown: 150C 8-pin MLPD (2x2mm) Package The AS1720A and AS1720B can be set to provide a strong initial closure current and is automatically switching to hold mode for On request SOIC 8 Package (reduced temperature range -40C power saving. The initial DC current, the hold current and the duty to +85C) cycle of the PWM can be adjusted by external resistors. An internal thermal sensor prevents damage of the circuit due to excessive 3 Applications heating up. The AS1720 is ideal for fluid and gas flow systems, industrial control, Both devices are optimized for driving electromechanical devices electrical heaters, motor speed control. such as valves, solenoids relays, actuators and positioners. Figure 1. AS1720 - Block Diagram Vsupply: +5V to +50V Internal VDDA typ. 3.3V 1 LDO & Ref Generator VDDHV 100nF AS1720 2 VDDA 30kHz Delay L Oscillator Free- Wheeling Diode R1 RL Thermal 4 3 adjustable Shutdown PWM & Duty cycle DUTY OUT Control 10nF R2 Current V ref Adjust VDDA 5 R PU VSS ENN 8 IH 7 IE 6 Off RIE RIH On Hold Current adjust Energising Current adjust www.austriamicrosystems.com/Solenoid-Relay-Driver/AS1720 Revision 1.04 1 - 12AS1720 Datasheet - P in A s s ig n me n t s 4 Pin Assignments Figure 2. Pin Out (Top View) 8 ENN VDDHV 1 VDDA 2 7 IH AS1720 DUTY 3 6 IE VSS OUT 4 5 Pin Description Table 2. Pin Descriptions Pin Name Pin Number Description Positive supply voltage VDDHV 1 Internal supply of 3.3V (typ.) VDDA 2 Duty-Cycle. By means of this pin the duty cycle can be adjusted between 20% and 90% during hold DUTY 3 phase. The duty cycle can be adjusted by a voltage source or an external resistor divider. Setting this pin to VDDA the 50% duty cycle is selected automatically. Current Source Output OUT 4 5 Ground VSS 6 Energize Current. This pin defines the current during energize phase by means of a resistor. IE 7 Hold Current. This pin defines the current during hold phase by means of a resistor. IH Enable Not. This pin can be used to switch on/off the current source (e.g. via a P), when the AS1720 is always powered on. Low during start-up: When VDDHV is applied, the device starts with the energise phase, followed by the hold phase. 8 ENN When the device is constantly powered on, it can be controlled by this pin. High: The output current source is switched off. Low: The device starts with the energise phase, followed by the hold phase. www.austriamicrosystems.com/Solenoid-Relay-Driver/AS1720 Revision 1.04 2 - 12