CS51221 CHERRY

Document overview

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Technical content

Features

I 1MHz Frequency Capability I Fixed Frequency Voltage Mode Operation, with Feed Forward I Thermal Shutdown I Under Voltage Lock-out I Accurate Programmable Max Duty Cycle Limit I 1A Sink/Source Gate Drive I Programmable Pulse by Pulse Over Current Protection I Leading Edge Current Sense Blanking I 75ns Shutdown Propagation Delay I Programmable Soft Start I Under Voltage Protection I Over Voltage Protection with Programmable Hysteresis I Bidirectional Synchronization I 25ns GATE Rise and Fall Time (1nF load) I 3.3V 3% Reference Voltage Output Package Options CS51221 Enhanced Voltage Mode PWM Controller CS51221

Description

16 Lead SO Narrow & PDIP

36V-72V to 5V/5A converter Rev. 3/26/99 Cherry Semiconductor Corporation

2000 South County Trail, East Greenwich, RI 02818

Tel: (401)885-3600 Fax: (401)885-5786 Email: info@cherry-semi.com Web Site: www.cherry-semi.com A Company ® The CS51221 fixed frequency feed forward voltage mode PWM controller contains all of the features necessary for basic voltage mode operation. This PWM controller has been opti- mized for high frequency prima- ry side control operation. In addition, this device includes such features as: Soft Start, accu- rate duty cycle limit control, less than 50µA startup current, over and under voltage protection, and bidirectional synchroniza- tion. The CS51221 is available in 16 lead PDIP and SO narrow surface mount packages. VIN (36V to 72V) 51k 0.01µF 470pF 20.25k 13k 510k 0.1µF IRF634 100 1µF 680pF 150 180 MOC81025 100µF SGnd VOUT (5V/5A) 2200pF 5.1k0.1µF SYNC 4.3k 20010k 1µF 330pF MBRB2545CT 100pF D11 BAS21 10k BAS21 18V22µF 11V FZT688 0.22µF 24.3k TL431 4:1 100:1 T2 2:5 UV OV VREF RT/CT ISET LGnd SS VFB COMP SYNC PGnd FF VC VCC ISENSE CS51221/2 GATE 160k 5.6k D13 V33MLA1206A23 4700pF

Lead Temperature Soldering: Absolute Maximum Ratings PIN SYMBOL PIN NAME VMAX VMIN ISOURCE ISINK GATE Gate Drive Output 15V -0.3V 1.0A Peak 1.0A Peak 200mA DC 200mA DC ISENSE Current Sense Input 6V -0.3V 1mA 1mA RTCT Timing Resistor/Capacitor 6V -0.3V 1mA 10mA FF Feed Forward 6V -0.3V 1mA 25mA COMP Error Amp Output 6V -0.3V 10mA 20mA V FB Feedback Voltage 6V -0.3V 1mA 1mA SYNC Sync Input 6V -0.3V 10mA 10mA UV Under Voltage 6V -0.3V 1mA 1mA OV Over Voltage 6V -0.3V 1mA 1mA I SET Current Set 6V -0.3V 1mA 1mA SS Soft Start 6V -0.3V 1mA 10mA V CC Logic Section Supply 15V -0.3V 10mA 50mA VC Power Section Supply 15V -0.3V 10mA 1.0A Peak 200mA DC VREF Reference Voltage 6V -0.3V Internally 10mA Limited PGnd Power Ground N/A N/A 1.0A Peak N/A 200mA DC LGnd Logic Ground N/A N/A N/A N/A

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT Electrical Characteristics: -40˚C < TA < 85˚C; -40˚C < TJ < 125˚C; 3V < VC < 15V; 4.7V < VCC < 15V; Rt=12K, Ct=390pF Unless otherwise stated. I Start/Stop Voltages Start Threshold 4.4 4.6 4.7 V Stop Threshold 3.2 3.8 4.1 V Hysteresis Start - Stop 400 850 1400 mV I CC @ Startup V CC < UVL Start Threshold 38 75 µA I Supply Current ICC Operating 9.5 14 mA IC Operating 1nF Load on GATE 12 18 mA IC Operating No switching 2 4 mA I Reference Voltage Total Accuracy 0mA < I REF < 2mA 3.2 3.3 3.4 V Line Regulation 6 20 mV Load Regulation 0mA < I REF < 2mA 6 15 mV Noise Voltage 10Hz < F < 10kHz (Note 1) 50 µV Op Life Shift T = 1000Hrs. (Note 1) 4 20 mV Fault Voltage 2.8 2.95 3.1 V V REF(OK) Voltage 2.9 3.05 3.2 V VREF(OK) Hysteresis 30 100 150 mV Current Limit 2 40 100 mA I Error Amp Reference Voltage V FB = COMP 1.234 1.263 1.285 V VFB Input Current V FB = 1.2V 1.3 2 µA Open Loop Gain (Note 1) 60 dB Unity Gain Bandwidth (Note 1) 1.5 MHz COMP Sink Current COMP = 1.4V, V FB = 1.45V 3 12 32 mA COMP Source Current COMP = 1.4V, V FB = 1.15V 1 1.6 2.0 mA COMP High Voltage V FB = 1.15V 2.8 3.1 3.4 V COMP Low Voltage V FB = 1.45V 75 125 300 mV PSRR Freq = 120Hz (Note 1) 60 85 dB SS Clamp, VCOMP SS = 1.4V, VFB = 0V, ISET = 2V 1.3 1.4 1.5 V COMP Max Clamp Note 1 1.7 1.8 1.9 V

Electrical Characteristics: -40˚C < TA < 85˚C; -40˚C < TJ < 125˚C; 3V < VC < 15V; 4.7V < VCC < 15V; Rt=12K, Ct=390pF Unless otherwise stated. CS51221 PARAMETER TEST CONDITIONS MIN TYP MAX UNIT I Oscillator Frequency Accuracy 260 273 320 kHz Voltage Stability 1 2 % Temperature Stability (Note 1) -40 ˚C < T J < 125˚C8 % Max Frequency (Note 1) 1 MHz Duty Cycle 80 85 90 % Peak Voltage (Note 1) 1.94 2.00 2.06 V Valley Clamp Voltage 0.90 0.95 1.00 V Valley Voltage (Note 1) 0.85 1.00 1.15 V Discharge Current 0.85 1.00 1.15 mA I Synchronization Input Threshold 0.9 1.4 1.8 V Output Pulse Width 200 320 450 ns Output High Voltage 100µA Load 2.1 2.5 2.8 V Input Resistance 35 70 140 k Ω SYNC to Drive Delay Time from SYNC to 100 140 180 ns GATE Shutdown Output Drive Current R SYNC = 1Ω 1.00 1.50 2.25 mA I GATE Driver High Saturation Voltage V C-GATE, VC = 10V, 1.5 2.0 V ISOURCE = 200mA Low Saturation Voltage GATE-PGnd, I SINK = 200mA 1.2 1.5 V High Voltage Clamp 11.0 13.5 16.0 V Output Current 1 nF load (Note 1) 1 1.25 A Output UVL Leakage GATE = 0V 1 50 µA Rise Time 1nF load, V C = 20V, 1V < GATE < 9V 60 100 ns Fall Time 1nF load, V C = 20V, 9V < GATE < 1V 25 50 ns Max Gate Voltage I GATE = 500µA .4 .7 1.0 V during UVL/Sleep I FeedForward (FF) Discharge Voltage I FF = 2mA 0.3 0.7 V Discharge Current FF = 1V 2 16 30 mA FF to GATE Delay 50 75 125 ns

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT I Overcurrent Protection Overcurrent Threshold I SET = 0.5V, Ramp ISENSE 0.475 0.500 0.525 V ISENSE to GATE Delay 50 90 125 ns I External Voltage Monitors Overvoltage Threshold OV increasing 1.9 2.0 2.1 V Overvoltage Hysteresis OV = 2.15V 10.0 12.5 15.0 µA Current Undervoltage Threshold UV increasing 0.95 1.00 1.05 V Undervoltage Hysteresis 25 75 125 mV I Soft Start (SS) Charge Current SS = 2V 40 50 70 µA Discharge Current SS = 2V 4 5 7 µA Charge Voltage 2.8 3.0 3.4 V Discharge Voltage 0.25 0.3 0.35 V Soft Start Clamp Offset FF = 1.25V 1.15 1.25 1.35 V Soft Start Fault Voltage OV = 2.15V or LV = 0.85V 0.1 0.2 V I Blanking Blanking Time 50 150 250 ns SS Blanking Disable V FB < 1 2.8 3.0 3.3 V Threshold COMP Blanking Disable V FB < 1, SS > 3V 2.8 3.0 3.3 V Threshold I Thermal Shutdown Thermal Shutdown (Note 1) 125 150 180 ˚C Thermal Hysteresis (Note 1) 5 10 15 ˚C Note 1: Guaranteed by design, not 100% tested in production. Electrical Characteristics: -40˚C < TA < 85˚C; -40˚C < TJ < 125˚C; 3V < VC < 15V; 4.7V < VCC < 15V; Rt=12K, Ct=390pF Unless otherwise stated.

Typical Performance Characteristics Package Pin Description PACKAGE PIN # PIN SYMBOL FUNCTION Block Diagram CS51221 3.1V VREF DISABLE FF Discharge 50µA VREF = 3.3V OSC S R Q 150ns Blank 13.5V SS PGnd VC GATE ISENSE COMP VFB ISET VREF VCC SYNC RTCT OV ENABLE VBG FF Latching Discharge UV Monitor UVL 2mA(maximum load current) Low Sat Gate Driver Thermal Shutdown EAMP ILIM OV MonitorMax SS Det (Sat Sense) 3.0V UV PWM Comp VREF OK UV Lockout Start/Stop 3.3V VO Off 5µA SS to 1.8V Max (Sat Sense) Max Duty Cycle3.0V LGnd 2V to 1V Trip Points Q (1.263V) Soft Start Clamp ON 16L PDIP & 16L SO Narrow 1 GATE External power switch driver with 1.0A peak capability. Rail to rail output occurs when the capacitive load is between 470pF and 10nF. SENSE Current sense comparator input. 3 SYNC Bidirectional synchronization. Locks to highest frequency. 4 FF PWM ramp. 5 UV Undervoltage protection monitor. 6 OV Overvoltage protection monitor. T/CT Timing resistor RT and capacitor CT determine oscillator frequency and maximum duty cycle, DMAX. 8I SET Voltage at this pin sets pulse-by-pulse overcurrent threshold. 9V FB Feedback voltage input. Connected to the error amplifier inverting input. 10 COMP Error amplifier output.

11 SS Charging external capacitor restricts error amplifier output

voltage during the power up or fault conditions. 12 LGnd Logic Ground. 13 V REF 3.3V reference voltage output. Decoupling capacitor can be selected from 0.01µF to 10µF. 14 V CC Logic supply voltage. 15 PGnd Output power stage ground. 16 V C Output power stage supply voltage.

RΘJC typ 28 42 ˚C/W RΘJA typ 115 80 ˚C/W 12Rev. 3/26/99 © 1999 Cherry Semiconductor Corporation D Lead Count Metric English Max Min Max Min 16L SO Narrow 10.00 9.80 .394 .386 16L PDIP 19.69 18.67 .775 .735

Ordering Information

CS51221EDR16 16L SO Narrow (tape & reel) CS51221EN16 16L PDIP CS51221 PACKAGE DIMENSIONS IN mm (INCHES) PACKAGE THERMAL DATA Cherry Semiconductor Corporation reserves the right to make changes to the specifications without notice. Please contact Cherry Semiconductor Corporation for the latest available information. Surface Mount Narrow Body (D); 150 mil wide Plastic DIP (N); 300 mil wide 0.39 (.015) MIN. 1.14 (.045) D Some 8 and 16 lead packages may have 1/2 lead at the end of the package. All specs are the same. .203 (.008) .356 (.014) REF: JEDEC MS-001 3.68 (.145) 2.92 (.115) 8.26 (.325) 7.62 (.300) 7.11 (.280) 6.10 (.240) .356 (.014) .558 (.022) 0.33 (.013) 6.20 (.244) 5.80 (.228) 4.00 (.157) 3.80 (.150) 1.57 (.062) 1.37 (.054) D 0.25 (0.10) 0.10 (.004) 1.75 (.069) MAX 1.27 (.050) 0.40 (.016) REF: JEDEC MS-012 0.25 (.010) 0.19 (.008)