LT1175 TYPICAL PERFORMANCE CHARACTERISTICSShutdown Input CurrentShutdown ThresholdsSHDN Pin Characteristics 25 2.5 15 VIN = 25V CHARACTERISTICS DO NOT POSITIVE THRESHOLD CHANGE SIGNIFICANTLY WITH 20 2.0 10 TEMPERATURE, SO A SINGLE CURVE IS SHOWN. POSITIVE CURRENT FLOWS INTO 15 1.5 5 SHDN PIN TJ = 25°C NEGATIVE THRESHOLD TJ = 125°C 10 1.0 0 THRESHOLD (V) T PIN CURRENT (μA) INPUT CURRENT (μA) J = –55°C IF SHDN PIN IS NEGATIVE WITH RESPECT TO INPUT VOLTAGE AND 5 0.5 –5 INPUT VOLTAGE IS LESS THAN 15V, DEVICE IS OFF NEGATIVE BREAKOVER POINT WILL BELOW THRESHOLD BE ABOUT 8V BELOW –VIN 0 0 –10 0 5 10 15 20 25 –50 –25 0 25 50 75 100 125 –25 –20 –15 –10 –5 0 5 10 15 20 25 INPUT VOLTAGE (V) TEMPERATURE (°C) SHUTDOWN TO GROUND VOLTAGE (V) 1175 G07 1175 G08 1175 G09 GND Pin CurrentRipple Rejection 20 100 VOUT = 12V (ADJUSTABLE) 16 80 WITH 0.1μF ACROSS DIVIDER RESISTOR 12 60 VOUT = 5V V POWER IN – VOUT = 2V (FIXED) T TRANSISTOR J = 25°C VOUT = 12V 8 IN DROPOUT 40 (ADJUSTABLE) REJECTION (dB) TJ = –55°C TJ = 25°C GROUND PIN CURRENT (mA) 4 20 IOUT = 100mA V V IN – VOUT = 2V IN – VOUT ≥ 3V C T OUT = 1μF TANT J = 25°C 0 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 10 100 1k 10k 100k 1M OUTPUT CURRENT (A) FREQUENCY (Hz) 1175 G10 RIPPLE REJECTION IS RELATIVELY INDEPENDENT OF INPUT VOLTAGE AND LOAD FOR CURRENTS BETWEEN 25mA AND 500mA. LARGER OUTPUT CAPACITORS DO NOT IMPROVE REJECTION FOR FREQUENCIES BELOW 50kHz. AT VERY LIGHT LOADS, REJECTION WILL 1175 G11 IMPROVE WITH LARGER OUTPUT CAPACITORS 1175ff 7