PDF CS3845B Data sheet ( Hoja de datos )

Número de pieza	CS3845B
Descripción	Current Mode PWM Control Circuit with 50% Max Duty Cycle
Fabricantes	Cherry Semiconductor Corporation
Logotipo
Hay una vista previa y un enlace de descarga de CS3845B (archivo pdf) en la parte inferior de esta página. Total 6 Páginas
No Preview Available ! CS3845B Current Mode PWM Control Circuit with 50% Max Duty Cycle Description Features The CS3845B provides all the neces- sary features to implement off-line fixed frequency current-mode control with a minimum number of external components. The CS3845B incorporates a precision temperature-controlled oscillator to minimize variations in frequency. An internal toggle flip-flop, which blanks the output off every other clock cycle, ensures that the duty-cycle never exceeds 50%. The undervoltage lock- out feature ensures that VREF is stabi- lized within specification before the output stage is enabled. The CS3845B has been optimized for lower start up current (500µA max). Other features include 1% trimmed band gap reference, pulse-by-pulse current limiting, and a high-current totem pole output for driving capaci- tive loads. Absolute Maximum Ratings Supply Voltage (ICC<30mA) ..........................................................Self Limiting Supply Voltage (Low Impedance Source)...................................................30V Output Current ...............................................................................................±1A Output Energy (Capacitive Load) .................................................................5µJ Analog Inputs (VFB, VSENSE)...........................................................-0.3V to 5.5V Error Amp Output Sink Current...............................................................10mA Lead Temperature Soldering Wave Solder (through hole styles only) ..........10 sec. max, 260°C peak Reflow (SMD styles only) ...........60 sec. max above 183°C, 230°C peak Block Diagram s Optimized for Off-line Use s Temperature Compensated Oscillator s 50% Maximum Duty-cycle Clamp s Low Start-up Current (500µA max) s Pulse-by-pulse Current Limiting s Undervoltage Active Pull Down s Double Pulse Suppression s 1% Trimmed Bandgap Reference s High Current Totem Pole Output Package Options 8 Lead PDIP & SO VCC Gnd VFB COMP OSC Sense VCC Undervoltage Lock-out 34V 8.4V/7.6V Error Amplifier - + 2.50V Oscillator Set/ 5.0 Volt Reset Reference R VREF Undervoltage Lockout R Toggle Flip-Flop NOR 2R R S R 1V Current PWM Sensing Latch Comparator Internal Bias VCC Pwr VREF VOUT Pwr Gnd COMP 1 VFB 2 Sense 3 OSC 4 8 VREF 7 VCC 6 VOUT 5 Gnd 14 Lead SO Narrow COMP 1 NC 2 VFB 3 NC 4 Sense 5 NC 6 OSC 7 14 VREF 13 NC 12 VCC 11 VCC Pwr 10 VOUT 9 Gnd 8 Pwr Gnd Rev. 11/19/98 Cherry Semiconductor Corporation 2000 South County Trail, East Greenwich, RI 02818 Tel: (401)885-3600 Fax: (401)885-5786 Email: [email protected] Web Site: www.cherry-semi.com 1 A ® Company 1 page VOSC OSC RESET Toggle F/F Output EA Output Switch Current VCC IO VO Figure 2: Timing Diagram Vupper Vlower ton tC ton = tC toff = tC+2td Figure 3: Timing Parameters. Circuit Description: continued Setting the Oscillator The parameters Tc and Td can be determined as follows: ( )tc = RTCT ln VREF - Vlower VREF - Vupper ( )td = RTCT ln VREF - IdRT - Vlower VREF - IdRT - Vupper Substituting in typical values for the parameters in the above formulas: VREF = 5.0V, Vupper = 2.7V, Vlower = 1.0V, Id = 8.3mA, then tc ≈ 0.5534RTCT ( )td = RTCT ln 2.3 - 0.0083 RT 4.0 - 0.0083 RT For better accuracy RT should be ≥10kΩ. Grounding toff High peak currents associated with capacitive loads neces- sitate careful grounding techniques. Timing and bypass td capacitors should be connected close to Gnd in a single point ground. The transistor and 5kΩ potentiometer are used to sample the oscillator waveform and apply an adjustable ramp to Sense. 5 5 Page

Páginas	Total 6 Páginas
PDF Descargar	[ Datasheet CS3845B.PDF ]

Hoja de datos destacado

Número de pieza	Descripción	Fabricantes
CS3845	Current Mode PWM Control Circuit	ON Semiconductor
CS3845B	Current Mode PWM Control Circuit with 50% Max Duty Cycle	Cherry Semiconductor Corporation

Número de pieza	Descripción	Fabricantes
SLA6805M	High Voltage 3 phase Motor Driver IC.	Sanken
SDC1742	12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters.	Analog Devices

DataSheet.es es una pagina web que funciona como un repositorio de manuales o hoja de datos de muchos de los productos más populares,
permitiéndote verlos en linea o descargarlos en PDF.

DataSheet.es | 2020 | Privacy Policy | Contacto | Buscar