LIA120S

Optically Isolated Linear Error Amplifier Features • Optocoupler, precision reference and error amplifier in single package • Low voltage operation 2.7V • 1.240V ± 2.5% reference • CTR Matching 15% • >70dB THD • 70dB CMRR • 3,750Vrms isolation • UL approval pending Description The LIA120 Optically Isolated Reference Amplifier combines Clare’s linear optical coupler technology with an industry standard 431 type precision programmable shunt regulator to provide very linear high gain with excellent temperature stability for a total gain error of less than 2dB. By using optical feedback, the LIA120 essentially eliminates temperature and gain variations due to current transfer ratio (CTR) changes in optocouplers while increasing the bandwidth up to 10X and easing engineering design constraints. The LIA120 is very well suited for high gain feedback amplifiers that require excellent linearity and low temperature variation such as isolated power supply feedback stages, modem audio transformer replacement, isolated industrial control signals, and sensor feedback. By using the LIA120, system designers can save precious board space and reduce component count. Available in an 8 pin surface mount package. Ordering Information Part # LIA120S LIA120STR 1 8 LED (Input) LIA120 Applications • Power supply feedback • Telecom central office supply • Telecom bricks • Modem transformer replacement • Digital telephone isolation Block Diagram Description 8 Pin Surface Mount (50/Tube) Tape and Reel (1000/Reel) NC K 2 7 COMP A 3 6 FB NC 4 5 GND DS-LIA120-R02.0 www.clare.com 1 LIA120 Absolute Maximum Ratings (@ 25˚ C) Parameter Photodiode Cathode-Anode Voltage Photodiode Anode-Cathode Voltage Input Voltage Input DC Current Total Power Dissipation (note 1) Operating Temperature Storage Temperature 1 Symbol Ratings Units VKAO 20 V VAKO 0.5 V AKO VLED 9 V ILED 20 mA PD 145 mW T -40 to +85 °C T -40 to +125 °C Absolute Maximum Ratings are stress ratings. Stresses in excess of these ratings can cause permanent damage to the device. Functional operation of the device at conditions beyond those indicated in the operational sections of this data sheet is not implied. Derate linearly from 25°C at a rate of 2.42 mW/ °C. Electrical Characteristics: Parameter Input Characteristics @ 25°C LED forward voltage Reference voltage Conditions ILED = 5 mA, VCOMP = VFB (Fig.1) ILED = 10 mA, VCOMP = VFB (Fig.1) TA = -40 to +85°C TA = 25°C TA = -40 to +85°C Symbol VF VREF Min 0.8 1.210 1.228 1.0 1.0 85 1 20 3750 Typ 1.2 1.24 32 2 2 100 226 110 0.001 0.21 0.3 1012 100 70 70 Max 1.4 1.265 1.252 3.0 3.0 115 0.1 100 Units V V mV % % % µA µA mA µA Ohm nA V Vrms Ω kHz dB dB Deviation of VREF over temperature - See Note 1 VREF (DEV) Transfer Characteristics @ 25°C Current Transfer Ratio in Feedback (IREF/ILED) /I ILED = 5mA, VREF = 0.5V (Fig.2) K1 K2 ILED = 5 mA, VCOMP = VFB, VKA = 5 V (Fig. 4) Current transfer ratio (IKA/ILED) /I Current Transfer Ratio Matching (IKA/IREF) /I ILED = 5mA, VKA = 5.0V K3 Feedback input current ILED = 10 mA, R1 = 10 kΩ (Fig.2) IREF Deviation of IREF over temperature - See Note 1 TA = -40 to +85°C IREF (DEV) Minimum drive current VCOMP = VFB (Fig.1) ILED (MIN) Off-state error amplifier current VIN = 6 V, VFB = 0 (Fig.3) IOFF Error amplifier output impedance - See Note 2 ILED = 0.1 mA to 15 mA, VCOMP = VFB, f