LT1684 Linear Technology, LT1684 Datasheet
LT1684
Available stocks
Related parts for LT1684
LT1684 Summary of contents
Page 1
... The LT1684 uses its own ring tone output as a reference for generating local supply rails using complementary high voltage external MOSFETs as dynamic level-shifting devices. This “active tracking” supply mode of operation ...
Page 2
... Industrial Grade ................................ – 125 C Storage Temperature Range ................. – 150 0.3V) Lead Temperature (Soldering, 10 sec).................. 300 0.3V OUT 12 AMPIN + 11 GATE + LIM 8 OUT – Current .......................................... – 350mA – Current ....................................... 20mA ORDER PART NUMBER LT1684CN LT1684CS LT1684IN LT1684IS ...
Page 3
... Shorted to OUT – – LIM Shorted to V Note 3: PWM inputs are high impedance through 100mV beyond the input thresholds. Note 4: 10k resistor from pin AMPIN to ground. + – , GATE Note 5: Guaranteed but not tested. LT1684 = MIN TYP MAX UNITS 680 950 A 6 ...
Page 4
... LT1684 W U TYPICAL PERFOR A CE CHARACTERISTICS + – DC Supply Current vs V – V 740 720 700 IN A – 1.6V 680 660 IN A – –1.6V 640 620 600 – V – V (V) 1684 G01 V – V Voltage GATE ATREF Magnitudes vs Temperature 14 ...
Page 5
... AMPIN (Pin 12): Output Amplifier Input. Connected to external filter components through series protection re- . Pull-down sistor (usually 5k). Thevenin DC resistance of external REF filter and protection components should be 10k for opti- mum amplifier offset performance. See Applications In- formation section. LT1684 + pin bias and = I + – I – ). ATREF GATE ...
Page 6
... W 1.25V –1.25V BG OUT 15k – CURRENT LIMIT 5k AMPIN + COMP1 COMP2 LT1684 Block Diagram + GATE 14V AT REF + LIM OUT 14V – GATE – LIM – V – ...
Page 7
... LT1684. The LT1684 uses its own output as a voltage reference for the FET level shifters, “suspending” itself (by these generated supply voltages) about the signal output. In this manner, the LT1684 can linearly generate a signal hundreds of volts in amplitude at its output, while main- . When OUT taining 10V local supply rails across the IC itself ...
Page 8
... Encoded PWM Signal Input Basics The LT1684 accepts a user-supplied PWM carrier that represents the desired output ring tone signal. This PWM input is normalized by the LT1684 such that ring tone output amplitudes can be accurately encoded into the PWM input. The LT1684 accepts a differential input to maximize rejec- tion of system transients and ground noise ...
Page 9
... Component selection and active tracking supply transformation will be described for the following 2-pole MFB infinite-gain lowpass filter. TRANSFORMATION LOAD + V IN – TRANSFORMATION LOAD LT1684 Active Tracking Supply Amplifier + – – LOAD R2 Active Tracking Supply Lowpass Multiple Feedback Filter – ...
Page 10
... However, bootstrapping an amplifier system about its own output creates a complex myriad of inherent stability and response issues. Attempting such a configuration with generic “jelly-bean” components is not recommended for the faint of heart or type-A personalities. The LT1684, however, makes for a simplistic approach to active track- –1 .005 ing component selection ...
Page 11
... U APPLICATIO S I FOR ATIO Active Filter Tuned Oscillator Block Diagram The LT1684 can be implemented easily into a telephone ringer circuit based on the active filter tuned oscillator topology, eliminating the need for a user-supplied PWM input signal. The LT1684’s active filter amplifier can be used as a high-Q bandpass filter element by configuring active tracking supply bandpass. The LT1684’ ...
Page 12
... V 7 1/2 LT1017 – V – 4 R10 10k 100pF 2 COMP1 BG OUT C1 20pF 3 COMP2 AMPIN LT1684 4 – LIM GATE D1 5 1N5817 – – GATE LIM 7 AT OUT REF –110V FB1: FERRONICS FMB1601 Active Filter Tuned Oscillator Ring Tone Generator ...
Page 13
... U TYPICAL APPLICATIO S LT1684 13 ...
Page 14
... LT1684 U TYPICAL APPLICATIO S 120V 6800pF 100k 100 11 1000pF + 10k GATE PWM COMP1 1000pF 10k IN 1 LIM IN B OUT LT1684 OUT COMP2 LIM AMPIN – 0.1 F 470pF GATE 300k 6 6800pF 100k –120V FB1: FERRONICS FMB1601 (716) 388-1020 14 5kW PWM-to-Analog Converter ...
Page 15
... TYP 0.014 – 0.019 (0.355 – 0.483) TYP LT1684 0.770* (19.558) MAX 0.065 (1.651) TYP 0.018 0.003 (0 ...
Page 16
... LT1684 U TYPICAL APPLICATIO 100pF + C1 PWM R4 R2 100pF INPUT 10k 10k – LT1684 C3 100pF COMP1 BG OUT R3 C4 20pF 5k COMP2 AMPIN – + LIM GATE FB1 – 1N4001 – + GATE LIM 300k AT OUT REF FB1: FERRONICS FMB1601 ...