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| LAB TOP VIEW COMP 1 V FB 2 I SENSE 3 R T /C T 4 8 7 6 5 SEME IP1844A SERIES IP1845A SERIES VREF VCC OUTPUT GROUND CURRENT MODE REGULATING PULSE WIDTH MODULATORS FEATURES * * * * * * Guaranteed 1% reference voltage tolerance Accurate oscillator discharge current Guaranteed 10% frequency tolerance Low start-up current (<500 mA) Under voltage lockout with hysteresis Output state completely defined for all supply and input conditions * Interchangeable with IP and UC1844/5 series for improved operation * 500kHz Oscillator operation 250kHz Output operation J Package - 8 Pin Ceramic DIP N Package - 8 Pin Plastic DIP D-8 Package - 8 Pin Plastic (150) SOIC TOP VIEW COMP 1 N/C 2 14 13 12 11 10 9 8 VREF N/C VCC VC OUTPUT GROUND POWER GROUND V FB 3 N/C 4 I SENSE 5 N/C 6 R T /C T 7 D-14 Package - 14 Pin Plastic (150) SOIC Part Number IP1844A IP2844A IP3844A IP1845A IP2845A IP3845A J-Pack 8 Pin N-Pack 8 Pin D-8 8 Pin D-14 14 Pin Order Information Temp. Range -55 to +125C -25 to +85C 0 to +70C -55 to +125C -25 to +85C 0 to +70C Note: To order, add the package identifier to the part number. eg. IP1844AD-14 IP3845AJ ABSOLUTE MAXIMUM RATINGS (Tcase = 25C unless otherwise stated) VCC IO Supply Voltage Output Current Output Energy Analog Inputs Error Amp Output Sink Current Power Dissipation Derate @ Tamb > 50C Power Dissipation Derate @ Tamb > 50C Power Dissipation Derate @ Tcase > 25C Storage Temperature Range Lead Temperature (low impedance source) (ICC < 30mA) (capacitive load) (pins 2 and 3) Tamb = 25C Tcase = 25C Tcase = 25C J, N Packages D Package J, N Packages +30V Self limiting 1A 5J -0.3V to +VCC 10mA 1W 10mW/C 725mW 7.25mW/C 2W 16mW/C -65 to 150C +300C Prelim. 2/95 PD PD PD TSTG TL (soldering, 10 seconds) Semelab plc. Telephone (01455) 556565. Telex: 341927. Fax (01455) 552612. LAB DESCRIPTION SEME IP1844A SERIES IP1845A SERIES The IP1844A/IP1845A series of switching regulator control circuits contain all the functions necessary to implement off-line, current mode switching regulators, using a minimum number of external parts. Functions included are voltage reference, error amplifier, current sense comparator, oscillator, totem-pole output driver and under-voltage lockout circuitry. In addition the IP1844A and IP1845A series of devices have a toggle flip-flop which blanks the output on every second clock pulse, thereby ensuring that the duty cycle never exceeds 50%. For applications requiring more flexible control, all devices feature an on-chip trimmed oscillator discharge current, allowing accurate control to maximum-duty-cycle by selection of timing components. This can be beneficial even when using the IP1844A or IP1845A series, as it allows optimum safety margins to be designed into the application. Although pin compatible with the standard IP1844/5 parts these devices offer improved performance in several areas. They also offer tighter specification and improved performance over the IP and UC1844/5 series, whilst retaining complete compatibility. BLOCK DIAGRAM VCC 7/12 34V GND 5/9 UNDER-VOLTAGE LOCKOUT ENABLE REFERENCE 5V REGULATOR INTERNAL BIAS 2.5V REG 8/14 VREF 16V (8.4V) 6V (0.5V) S R 3.6V R T /CT 4/7 VREF STATUS LATCH 7/11 VC OSCILLATOR Q T ERROR AMP S R R 1V CURRENT SENSE COMPARATOR PWM LATCH TOGGLE FLIP FLOP * 6/10 OUTPUT 5/8 POW ER GROUND 2R V FB COMP I SENSE 2/3 1/1 * 1844A and 1845A series only. Values in brackets are for IP1845 series. PIN NUMBERS 1st Number - N, J and 8 Pin D Packages 2nd Num ber - 14 Pin D Package. 3/5 RECOMMENDED OPERATING CONDITIONS VCC IO Supply Voltage 1 Output Current Analog Inputs (pins 2 and 3) IP1844A , IP1845A IP2844A , IP2845A IP3844A , IP3845A Error Amp Output Sink Current Operating Ambient Temperature Range 30V 0 to 200mA -0.3V to 3V 0 to 2mA -55 to 125C -25 to 85C 0 to 70C Notes: 1. Lower limit set by under voltage lockout specification. Telephone (01455) 556565. Telex: 341927. Fax (01455) 552612. Prelim. 2/95 Semelab plc. LAB Parameter Output Voltage Input Regulation Output Regulation Temperature Stability Total Output Variation Output Noise Voltage Long Term Stability Output Short Circuit Current Frequency Voltage Stability Temperature Stability Amplitude Discharge Current Line, Load, Temp f = 10Hz to 10kHz TJ = 25C TJ = 125C @ 1000Hrs VREF = 0 SEME IP1844A SERIES IP1845A SERIES ELECTRICAL CHARACTERISTICS (Over Full Operating Temperature Range unless otherwise stated) Test Conditions 1 REFERENCE SECTION IO = 1mA VCC = 12V to 25V IO = 1mA to 20mA TJ = 25C IP1844A , IP1845A IP2844A , IP2845A Min. Typ. Max. 4.95 5.00 6 6 0.2 4.90 50 5 30 80 25 160 5.05 20 25 0.4 5.10 Min. 4.90 IP3844A IP3845A Typ. 5.00 6 6 0.2 Max. Units 5.10 20 25 0.4 5.18 V mV mV C V V 25 160 mV mA 4.82 50 5 30 80 OSCILLATOR SECTION TJ = 25C VCC = 12V to 25V TA = Min to Max VPIN4 Peak to Peak TJ = 25C TA = Min to Max (Note 2) 47 52 0.2 5 1.7 57 1 47 52 0.2 5 1.7 57 1 kHz % % V 7.8 7 2.45 8.3 8.8 9 7.8 7 2.42 8.3 8.8 9 mA ERROR AMP SECTION Input Voltage Input Bias Current Open Loop Voltage Gain Unity Gain Bandwidth Supply Voltage Rejection Output Sink Current Output Source Current VOUT High VOUT Low VCC = 12V to 25V VPIN2 = 2.7V VPIN2 = 2.3V VPIN2 = 2.3V VPIN2 = 2.7V VPIN1 = 1.1V VPIN1 = 5V RL = 15k RL = 15k VO = 2V to 4V VPIN1 = 2.5V 2.50 -0.3 2.55 -1 2.50 -0.3 2.58 -2 V A dB MHz dB mA V 65 0.7 60 2 -0.5 5 90 1 70 6 -0.8 6 0.7 1.1 65 0.7 60 2 -0.5 5 90 1 70 6 -0.8 6 0.7 1.1 NOTES 1. Test Conditions unless otherwise stated: VCC = 15V* , RT = 10k , CT = 3.3nF , f = 52kHz. *Adjust VCC above start threshold before setting at required level. 2. Output frequency is half the oscillator frequency. All specifications apply over the full operating temperature range unless otherwise stated. (See Ordering Information for further details). Semelab plc. Telephone (01455) 556565. Telex: 341927. Fax (01455) 552612. Prelim. 2/95 LAB Parameter Gain Maximum Input Signal Supply Voltage Rejection Input Bias Current Delay to Output SEME IP1844A SERIES IP1845A SERIES ELECTRICAL CHARACTERISTICS (Over Full Operating Temperature Range unless otherwise stated) Test Conditions 1 CURRENT SENSE SECTION See Notes 2,3 VPIN1 = 5V VC = 12V to 25V (Note 2) IP1844A , IP1845A IP2844A , IP2845A Min. Typ. Max. 2.85 0.9 60 3 1 70 -2 150 -10 300 0.4 2.2 3.15 1.1 Min. 2.85 0.9 60 IP3844A IP3845A Typ. 3 1 70 -2 150 0.1 1.5 Max. Units 3.15 1.1 V/V V dB -10 300 0.4 2.2 A ns OUTPUT SECTION Output Low Level Output High Level Rise Time Fall Time UVLO Saturation Upper Threshold (VCC) Lower Threshold (VCC) Start-up Current Operating Supply Current VCC Zener Voltage Maximum Duty Cycle Minimum Duty Cycle VPIN2 = 0V VPIN3 = 0V ICC = 25mA IP1844A Series IP1845A Series ISINK = 20mA ISINK = 200mA ISOURCE = 20mA ISOURCE = 200mA CL = 1nF CL = 1nF VCC = 6V IP1844A Series IP1845A Series IP1844A Series IP1845A Series IL = 1mA 0.1 1.5 13 12 13.5 13.5 50 50 0.7 15 7.8 9 7 16 8.4 10 7.6 0.3 11 14 30 47 34 48 V V 13 12 150 150 1.1 17 9 11 8.2 0.5 15 17 40 50 0 30 46 14.5 7.8 8.5 7 13.5 13.5 50 50 0.7 16 8.4 10 7.6 0.3 11 14 34 48 150 150 1.1 17.5 9 11.5 8.2 0.5 15 17 40 50 0 ns V UNDER-VOLTAGE LOCKOUT SECTION V V TOTAL STANDBY CURRENT mA mA V PWM SECTION % NOTES 1. Test Conditions unless otherwise stated: VCC = 15V* , RT = 10k , CT = 3.3nF , f = 52kHz. *Adjust VCC above start threshold before setting at required level. All specifications apply over the full operating temperature range unless otherwise stated. (See Ordering Information for further details). 2. Parameter measured at trip point of latch with VPIN2 = 0V 3. Gain defined as: VPIN1 VPIN3 0 VPIN3 0.8 A= Semelab plc. Telephone (01455) 556565. Telex: 341927. Fax (01455) 552612. Prelim. 2/95 LAB APPLICATIONS INFORMATION Oscillator Waveforms and Maximum Duty Cycle LARGE R T SMALL C T SEME IP1844A SERIES IP1845A SERIES VPIN4 (VPIN7 for 14 pin D package) INTERNAL CLOCK OUTPUT - Max. Duty Cycle VPIN6 (VPIN10 for 14 pin D package) V REF 8 RT RTCT 4 CT GND 5 LARGE C T SMALL R T VPIN4 (VPIN7 for 14 pin D package) INTERNAL CLOCK OUTPUT - Max. Duty Cycle VPIN6 (VPIN10 for 14 pin D package) Oscillator timing capacitor C T is charged by V REF tc 0.55 RTCT through RT and discharged by an internal current source. .0063 RT - 2.3 During the discharge time, the internal clock signal td RTCT Rn .0063 - 4 blanks the output to the low state. Selection of RT and 1 CT therefore determines both oscillator frequency and Resultant frequency f = (tc + td) maximum duty cycle. Charge and discharge times are determined by the formulae: For RT > 5k, Resultant frequency f 1.8 (RTCT) ( ) Open-Loop Laboratory Test Fixture VREF RT 4.7k 2N2222 100k 1k ERROR AMP ADJUST 5k ISENSE ADJUST 4.7k VCC 1 COMP 2 VFB 3 ISENSE 4 R T /C T VREF 8 VCC 7 O/P 6 GND 5 GROUND CT 0.1 F 0.1 F 1k 1kW OUTPUT High peak current associated with capacitive loads necessitate careful grounding techniques. Timing and bypass capacitors should be connected close to pin 5 in a single point ground. The transistor and 5K potentiometer are used to sample the oscillator wave form and apply an adjustable ramp to pin 3. Semelab plc. Telephone (01455) 556565. Telex: 341927. Fax (01455) 552612. Prelim. 2/95 LAB OUTPUT SATURATION CHARACTERISTICS 4 100 SAT U R AT IO N VO L TAG E (V) 80 TA = 25C TA = -55C 2 (dB) 3 VCC = 15V 60 VO LT AG E G AIN 40 SEME IP1844A SERIES IP1845A SERIES TYPICAL PERFORMANCE CHARACTERISTICS ERROR AMPLIFIER OPEN-LOOP FREQUENCY RESPONSE 0 -45 PH ASE () B -90 SOURCE SAT 1 ( VCC- VOH) 20 AV 0 -135 -180 SINK SAT (VOL ) 0 .01 .02 .03 .04 .05 .07 .1 .2 .3 .4 .5 .7 1.0 10 100 1k 10k FREQUENCY (Hz) 100k 1M 10M OUTPUT CURRENT, SOURCE / SINK (A) UNDER VOLTAGE LOCKOUT 1844A SERIES 20 20 UNDER VOLTAGE LOCKOUT 1845A SERIES 15 15 10 I CC (m A) 0 5 10 VCC (V) 15 20 I CC (m A) 10 0.5 0.5 0 0 0 2.5 5 VCC (V) 7.5 10 Semelab plc. Telephone (01455) 556565. Telex: 341927. Fax (01455) 552612. Prelim. 2/95 |
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