MAX8785AETI+T Maxim Integrated Products, MAX8785AETI+T Datasheet
MAX8785AETI+T
Specifications of MAX8785AETI+T
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MAX8785AETI+T Summary of contents
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... Notebook LCDs LCD TVs and Monitors Simplified Operating Circuit appears at end of data sheet. ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. Full-Bridge Controller for Piezoelectric Transformers o Resonant, All n-Channel, Full-Bridge Topology o Wide Input-Voltage Range (4 ...
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Full-Bridge Controller for Piezoelectric Transformers ABSOLUTE MAXIMUM RATINGS BATT, RATE, LX1, LX2 to GND .............................-0.3V to +30V BST1, BST2 to GND ...............................................-0.3V to +36V BST1 BST2 to V ..................................-0.3V to +30V DD1 DD2 BST1 to LX1..............................................................-0.3V to ...
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ELECTRICAL CHARACTERISTICS (continued 12V 5.35V, R SHDN BATT DD1 DD2 are +25°C.) A PARAMETER IFB Lamp-Out Threshold IFB-to-COMP Transconductance COMP Output Impedance COMP Maximum Voltage Threshold COMP Discharge Current ...
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Full-Bridge Controller for Piezoelectric Transformers ELECTRICAL CHARACTERISTICS (continued 12V 5.35V, R SHDN BATT DD1 DD2 are +25°C.) A PARAMETER SHDN Input Bias Current TFLT Charging Current TFLT Trip Threshold ...
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ELECTRICAL CHARACTERISTICS (continued 12V SHDN BATT DD1 DD2 A PARAMETER Current-Limit Leading-Edge Blanking IFB Regulation Point IFB Input Bias Current IFB Lamp-Out Threshold IFB-to-COMP Transconductance COMP Discharge Current During Overvoltage Initial ...
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Full-Bridge Controller for Piezoelectric Transformers (Circuit of Figure 12V +25°C, unless otherwise noted LOW INPUT-VOLTAGE OPERATION (V = 12V) IN MAX8785A toc01 V = 2.0V CNTL SEL = GND 10μs/div CH1: 10V/div CH2: ...
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Figure 12V +25°C, unless otherwise noted MAXIMUM SWITCHING FREQUENCY vs. R 100 100 R (kΩ LINE REGULATION CC 5.362 5.361 5.360 5.359 5.358 ...
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Full-Bridge Controller for Piezoelectric Transformers PIN NAME Duty Ratio Ramp Adjustment Input. Connect a feed-forward network between BATT and RATE to adjust the 1 RATE slope of the internal ramp that adjusts the H-bridge duty cycle with input voltage. 2 ...
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PIN NAME Arc Fault-Detection Input. When the peak voltage on OLF rises above the internal threshold of 1.2V (typ), an internal current source starts charging the TFLT capacitor. The MAX8785A sets the fault latch and disables the 24 OLF gate ...
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Full-Bridge Controller for Piezoelectric Transformers 2A VIN GND C2 0.22μF VCC C3 R10 1.0μF 280kΩ 3.6V ON/OFF DIMMING LSYNC R11 90kΩ R12 150kΩ C4 47nF C5 10nF C6 0.22μF Figure 1. Typical Operating Circuit 10 ______________________________________________________________________________________ VCC BATT V DD1 ...
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V CC 4.12V LINEAR BATT REGULATOR GND RATE HF F. IFB RECT 800mV ERROR AMPLIFIER COMP 1mA 2.25V OVERVOLTAGE COMPARATOR VFB 230mV SHORT-CIRCUIT COMPARATOR 800mV IFB OPEN-LAMP COMPARATOR 1.2V OLF OLF COMPARATOR Figure 2. MAX8785A Block Diagram Detailed ...
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Full-Bridge Controller for Piezoelectric Transformers PRIMARY OUT Figure 3. Typical Multilayer PZT in Longitudinal Mode The MAX8785A can achieve 10:1 dimming range with the DPWM method. CCFL brightness can be adjusted using analog or digital ...
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CCFL strike voltage is reached and the lamp impe- dance begins to decrease. The operating frequency continues to decrease as the lamp impedance drops until the correct operating point is reached, somewhere between Points C and D. Figure 5 ...
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Full-Bridge Controller for Piezoelectric Transformers The frequency of the internal DPWM oscillator is adjustable through a resistor connected between LF and GND. The DPWM frequency is given by: ≈ × 150 Ω 208 Hz k DPWM The adjustable ...
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Open PZT Protection The MAX8785A has protection against faulty connections of PZT to the PC board. The OLF pin is used to detect high-voltage conditions on the secondary side of the transformer. When the OLF voltage exceeds 1.2V (typ), a ...
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Full-Bridge Controller for Piezoelectric Transformers Setting the Lamp Current The MAX8785A senses the lamp current flowing through resistor R1 (Figure 1) connected between the low-voltage terminal of the lamp and ground. The voltage across R1 is fed to IFB and ...
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Setting the Fault Delay Time The TFLT capacitor determines the delay time for both open-lamp fault and arc fault. The MAX8785A charges the TFLT capacitor with a 0.75µA current source during open-lamp fault and charges the TFLT capacitor with a ...
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Full-Bridge Controller for Piezoelectric Transformers VIN GND BATT GND VCC V SEL RATE SHDN ON/OFF CNTL DIMMING LSYNC LSYNC HF LF COMP PCOMP TFLT Chip Information TRANSISTOR COUNT: 6281 PROCESS: BiCMOS 18 ______________________________________________________________________________________ V DD1 V DD2 CC FLT GH1 ...
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... Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 19 © 2008 Maxim Integrated Products ...