ATLS1A101 Datasheet | AT

Analog Technologies Features Ultra Low Noise: <6µA- High Output Current: 1A High Absolute Accuracy: <0.1% Low Noise Constant Current Laser Driver ATLS1A101 Figure 1 is the actual size top view of the ATLS1A101, which shows the pin names and locations. APPLICATIONS Figure 2 shows a stand-alone application circuit, where W1 sets the current limit and the output current at the same time. It is remended that the current limit is set to 1.1 times of the output current. S1 is the shut down switch. The internal equivalent input circuit of SDN pin is a pull-up resistor of 100K being connected to VPS. If choose not to use a switch (S1) to control the laser, leave the SDN pin unconnected. D1 is the laser diode, which is float from the ground and the VPS, with its anode connected to the LDA, pin 9, and cathode connected to the LDC, pin 10. D2 is an LED, indicating when the control loop works properly, that is: the output current equals to the input set value. If choose not to use an LED for indicating the working status, leave the LPGD pin unconnected. Adjusting W1, set input voltages of LILM, pin 3, and LISL, pin 4, and the current limit and the output current will respectively be: I_limit = 1.1- LILM(V)/2.5V (A), I_output = LISL(V)/2.5V (A). LILM and LISL should never be left float. Otherwise, the output current will go too high a value and the laser might be damaged. In addition to using the LPGD pin for monitoring the working status of the controller, the output current can be monitored directly by measuring the voltage of LDC pin. The equation is: I_out = LDC(V)/0.5V (A). For example, when seeing LDC = 0.25V, the output current is 0.25V/0.5V = 0.5A. Figure 3 shows an application where ATLS1A101 is interfaced with a micro-controller. In this circuit, the input current can be set by a DAC (Digital to Analog Converter), the current limit can either be set by a POT (Potentiometer), a pair of resistors, or the same DAC. The output current can now be monitored by an ADC...