Philips Semiconductors Product specification Switched-mode power supply control circuit DESCRIPTION NE/SE5561 PIN CONFIGURATION The NE5561/SE5561 is a control circuit for use in switched-mode power supplies. It contains an internal temperature- compensated supply, PWM, sawtooth oscillator, overcurrent sense latch, and output stage. The device is intended for low cost SMPS applications where extensive housekeeping functions are not required. D, FE, N Packages FEATURES • Micro-miniature (D) package • Pulse-width modulator • Current limiting (cycle-by-cycle) • Sawtooth generator • Stabilized power supply • Double pulse protection • Internal temperature-compensated reference VCC 1 8 GND VZ 2 7 OUTPUT FEEDBACK 3 6 CURRENT SENSE GAIN 4 5 RT, CT Figure 1. Pin Configuration APPLICATIONS • Switched-mode power supplies • DC motor controller inverter • DC/DC converter ORDERING INFORMATION TEMPERATURE RANGE ORDER CODE DWG # 8-Pin Plastic Dual In-Line Package (DIP) DESCRIPTION 0 to +70°C NE5561N SOT97-1 8-Pin Plastic Dual In-Line Package (DIP) -55 to +125°C SE5561N SOT97-1 8-Pin Ceramic Dual In-Line Package (CERDIP) -55 to +125°C SE5561FE 0580A 0 to +70°C NE5561D SOT96-1 8-Pin Small Outline (SO) Package BLOCK DIAGRAM RT, CT 5 REF VOLTAGE SAWTOOTH GENERATOR VCC + ERROR AMP FEEDBACK 3 – 7 OUTPUT S LATCH PWM R GAIN 4 – 0.5V 1 CURRENT SENSE 6 8.2V STABILIZED SUPPLY VCC + 2 VZ 8 GND SL00385 Figure 2. Block Diagram 1994 Aug 31 1 853-0889 13721 Philips Semiconductors Product specification Switched-mode power supply control circuit NE/SE5561 ABSOLUTE MAXIMUM RATINGS SYMBOL PARAMETER RATING UNIT Supply1 VCC Voltage-forced mode +18 V Current-fed mode 30 mA mA Output transistor (at 20-30V max) IOUT Output current 40 VOUT Output voltage VCC+1.4V V 98 % 0.75 W SE5561 -55 to +125 °C NE5561 0 to 70 °C Output duty cycle PD Maximum total power dissipation TA Operating temperature range NOTES: 1. See Voltage-Current-fed supply characteristic curve. DC ELECTRICAL CHARACTERISTICS VCC=12V, TA=25°C, unless otherwise specified. SYMBOL PARAMETER TEST CONDITIONS SE5561 NE5561 UNIT Min Typ Max Min Typ Max 3.75 3.84 3.57 3.75 3.96 V 3.88 3.55 3.98 V 8.8 7.8 8.8 V Reference section VREF VZ Internal ref voltage Internal zener ref TA=25°C 3.69 Over temperature 3.65 *IL=7mA 7.8 8.2 8.2 Temp. coefficient of VREF ±100 ±100 ppm/°C Temp. coefficient of VZ ±200 ±200 ppm/°C Oscillator section Frequency range Initial accuracy Duty cycle range Over temperature 50 RT and CT constant fO=20kHz 100k 50 5 0 100k 5 98 0 Hz % 98 % -10 µA -20 µA Current limiting IIN Input current Pin 6=250mV TA=25°C -2 Over temp. Single pulse inhibit delay Inhibit delay time for 20% overdrive at -10 -2 -20 IOUT=20mA 0.88 1.10 0.88 1.10 µs IOUT=40mA 0.7 0.8 0.7 0.8 µs .500 .600 .500 .600 V Current limit trip level .400 .400 Error amplifier Open-loop gain 60 Feedback resistor BW Small-signal bandwidth VOH Output voltage swing VOL Output voltage swing 60 10k dB Ω 10k 3 3 6.2 MHz 6.2 0.7 V 0.7 V Output stage IOUT Output current VCE Sat 1994 Aug 31 Over temperature IC=20mA, Over temp. 2 20 20 0.4 mA 0.4 V Philips Semiconductors Product specification Switched-mode power supply control circuit NE/SE5561 DC ELECTRICAL CHARACTERISTICS VCC=12V, TA=25°C, unless otherwise specified. SYMBOL PARAMETER TEST CONDITIONS SE5561 Min Typ NE5561 Max Min Typ Max UNIT Supply voltage/current ICC Supply current VCC Supply voltage IZ=0, voltage-forced TA=25°C 10.0 10.0 Over temp. 13.0 13.0 ICC=10mA, current-fed 20.0 ICC=30mA current 20.0 21.0 22.0 19.0 30.0 20.0 10.5 8 21.0 24.0 30.0 mA V Low supply protection Pin 1 threshold 1994 Aug 31 8 3 9 9 10.5 V Philips Semiconductors Product specification Switched-mode power supply control circuit NE/SE5561 TYPICAL PERFORMANCE CHARACTERISTICS Error Amplifier Open-Loop Gain Error Amplifier Open-Loop Phase 0 50 –30 GAIN (dB) 40 30 20 10 0 1k 10k 100k 1M 100 90 80 –60 70 δ (%) PHASE ANGLE (DEG) 60 –90 60 50 40 –120 30 20 –150 10 0 –180 1k 10M Transfer Curve of Pulse-Width Modulator Duty Cycle vs Input Voltage 10k 100k 1M 0 10M 1 2 3 4 5 6 V4 FREQUENCY (Hz) FREQUENCY (Hz) Typical Frequency Plot vs RT and CT 1000 1.25 100 PT = VCC ICC + (VCC – VZ) IZ + [V7 I7 x DUTY CYCLE] 1.00 R=5kΩ 50 0.50 2 R=10kΩ 30 0.75 f (kHz) TOTAL PWR DISSIPATION (WATTS) Power Derating Curve 20 R=20kΩ 10 R=40kΩ 5 5 3 NE NE5561 RT CT 0.25 2 SE 1 0 25 50 70 125 100 AMBIENT TEMPERATURE (°C) 2 150 2.5 3 3.5 4 4.5 C (nF) Maximum Duty Cycle vs Base Voltage on Q1 Start-Up Circuit Slow-Start Voltage MAXIMUM DUTY CYCLE (%) 100 V4 δ MAX (%) 90 VZ 80 2 70 NE5561 R1 60 50 4 V1 Q1 40 30 C R2 20 10 0 0 1 2 3 V1 4 5 t max is a function of f R2 VZ V BEQ1 R1 R2 Figure 3. Typical Performance Characteristics 1994 Aug 31 4 t = R’C SL00386 Philips Semiconductors Product specification Switched-mode power supply control circuit NE/SE5561 initially going to the extreme maximum (δ>90%). Either overcurrent limit or slow-start circuitry must be employed to limit duty cycle to a safe value during start-up. Both may be used, if desired. NE5561 Voltage-Current-Fed Supply Characteristics To implement slow-start, the start-up circuit can be used. The divider R1 and R2 sets a voltage, buffered by Q1, such that the output of the error amplifier is clamped to a maximum output voltage, thereby limiting the maximum duty cycle. The addition of capacitor C will cause this voltage to ramp-up slowly when power is applied, causing the duty cycle to ramp-up simultaneously. mA 20 Overcurrent limit may be used also. To limit duty cycle in this mode, the switch current is monitored at Pin 6 and the output of the 5561 is disabled on a cycle-by-cycle basis when current reaches the programmed limit. With current limit control of slow-start, the duty cycle is limited to that value, just allowing maximum switch current to flow. (Approximately 0.50V measured at Pin 6.) 10 V 0 0 10 20 30 Current-Fed Dropping Resistor APPLICATIONS VS 5V, 0.5A Buck Regulator Operates from 15V The converter design shows how simple it is to derive a TTL supply from a system supply of 15V (see Figure 1). The NE5561 drives a 2N4920 PNP transistor directly to provide switching current to the inductor. RVCC 1 VCC Overall line regulation is excellent and covers a range of 12V to 18V with minimal change (<10mV) in the output operating at full load. GND 8 As with all NE5561 circuits, the auxiliary slow start and δMAX circuit is required, as evidenced by Q1. The δMAX limit may be calculated by using the relationship: * V S CC (10 20mA) V R VCC + NOTE: See DC Electrical Characteristics for Current Fed VCC Range. R2 (8.2V) + R1 ) R2 The maximum duty cycle is then determined from the pulse-width modulator transfer graph, with R1 and R2 being defined from the desired conditions. SL00387 Figure 4. NE5561 Voltage-Current-Fed Supply Characteristics NE5561 START-UP The start-up, or initial turn-on, of this device requires some degree of external protective duty cycle limiting to prevent the duty cycle from 1994 Aug 31 V MAX 5