AS2214 Primary Side PWM Controller Features Description • • • • Low Startup Current • The AS2214 is a full featured, pulse width modulation controller. Based on an improved AS3842, the AS2214 provides additional features that reduce component count and improve specifications in a wide range of power supply designs. The added functionality includes AC power and bulk voltage sensing, over-voltage input, as well as the ability to latch off or bounce through different fault conditions. Oscillator trimmed for precision duty cycle clamp • Standard temperature range extended to 105°C • • Remote on / off control • Standard current mode control Bulk and AC sensing Soft Start Single-start or auto-restart modes The PWM function is controlled by the current sense comparator for normal current mode control and a second comparator for voltage mode soft start. A buffered RAMP signal is available for slope compensation without loading the oscillator. The output stage is a high current totem pole output that sees only 85 ns delay from the PWM comparator. Buffered Ramp for slope compensation Pin Configuration — The AS2214 requires less than 10µA of startup current. The undervoltage lockout (UVLO) thresholds are nominally 13.8V for turn on and 8 V for turn off. A precision 2.5 V bandgap reference serves as an input for the error amplifier. The oscillator discharge current is trimmed to provide guaranteed duty cycle clamping. Top view VCC 1 14 OUT VREG 2 13 GND COMP 3 12 BOK VFB 4 11 LEN ISNS 5 10 ACP SS 6 9 OV RAMP 7 8 RT/CT Ordering Information Package 14-Pin Plastic DIP ASTEC Semiconductor Temperature Range 0 to 105° C 83 Order Code AS2214N Primary Side PWM Controller AS2214 Functional Block Diagram VCC AC DETECT A CP 5V enab le (LEN) LEN V REG 5V Reg. V REG 6V 50µA UV LO V REG BOK (BULK_UV ) 2V 5 6µA (CLR) SS 3V 95 SS LOGIC OV (RUN) (OV ) 2V 5 ISNS COMP VFB 2V 5 2R CM PWM VCC 1V R (PWM) OUT SS PWM RA MP (BLA NK) OSC RT/CT x1 ASTEC Semiconductor 84 GND ASTEC Semiconductor 85 BOK OV LEN 0 0 1 0 1 0 0 1 0 1 0 0 1 1 0 0 0 1 1 1 2V5 3V9 1V7 VREG 1 0 1 0 - 1 2V5 •Q Q 0 0 - 1 •Q Q PRESET R S ENBL •Q Q VOV PRESET R S ENBL 0 0 - - - 0 OV •Q Q R S Preset ENABL Faulted •Q R PRESET Q S ENBL Started V REG Q •Q PWM_Disable PRESET R S ENBL Latch_bias 2V7 SS 6µA V REG Primary Side PWM Controller AS2214 AS2214 Soft Start Logic Primary Side PWM Controller AS2214 Pin Function Description Pin Number Function Description 1 VCC Positive supply voltage for the IC. 2 VREG Output of 5V series regulator. 3 COMP 4 VFB 5 ISNS A voltage proportional to inductor current is connected to this pin. The PWM uses this information to terminate the gate drive of the output. 6 SS This pin provides a 6µA current source to linearly charge an external capacitor. This pin is compared to the RAMP pin in the soft start comparator, terminating output pulses when RAMP goes above the SS voltage. 7 RAMP This pin is a level-shifted and buffered oscillator signal used to provide slope compensation to the current sense signal. The pin also serves as the non-inverting input of the softstart comparator. 8 RT/CT Oscillator frequency and maximum duty cycle are set by connecting a resistor (RT) to VREG and a capacitor (CT) to ground. 9 OV This pin latches SS low when pulled above 2.5 V. The latch can be reset by pulling OV above 4 V then back to ground. 10 ACP This pin detects the presence of AC signal and drives LEN high. 11 LEN This pin must be high to enable starting. The pin can also clear all latches by going low then high. 12 BOK This pin monitors the bulk voltage through a resistor divider and, when BOK exceeds 2.5 V, provides a 50µA current source for hysteresis. When BOK drops below 2.5V, SS is pulled low and the hysteresis current is turned off. Auto-restart after a brown-out is possible. 13 GND Circuit common ground. 14 OUT This totem pole output is designed to directly drive a power MOSFET switch capable of sourcing and sinking peak currents up to 1 A. This pin is the error amplifier output. Typically used to provide loop compensation to maintain VFB at 2.5 V. Inverting input of the error amplifier. The non-inverting input is a trimmed 2.5 V bandgap reference. ASTEC Semiconductor 86 Primary Side PWM Controller AS2214 Absolute Maximum Ratings Parameter Symbol Rating Unit IREF IOUT VCC VOUT PD TJ TSTG TL 200 1 20 20 500 150 – 65 to 150 300 mA A V V mW °C °C °C Reference Current Output Current Supply Voltage Output Voltage Continuous Power Dissipation at 25° C Junction Temperature Storage Temperature Range Lead Temperature, Soldering 10 Seconds Stresses greater than those listed under ABSOLUTE MAXIMUM RATINGS may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or any other conditions above indicated in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect reliability. Recommended Conditions Typical Thermal Resistance Parameter Symbol Rating Unit Package θJA θJC Typical Derating Supply Voltage VCC 10 - 15 V 14L PDIP 85° C/W 40° C/W 11.7 mW/°C Oscillator FOSC 50 - 250 kHz Electrical Characteristics Electrical Characteristics are guaranteed over full junction temperature range (0 to 105° C). Ambient temperature must be derated based on power dissipation and package thermal characteristics. Unless otherwise specified, the conditions of test are VCC = 15 V; BOK = 3 V; OV = 0V; RT = 680 Ω; CT = 10 nF. To override UVLO, VCC should be raised above 18 V prior to test. Parameter Symbol Test Condition Min Typ Max Unit 2.465 2.500 2.535 V -0.1 -1 Error Amplifier Input Voltage VFB Input Bias Current IBIAS Voltage Gain AVOL Transconductance TJ = 25°C 2 ≤ VCOMP ≤ 4 V µA 65 90 dB 1 mA/mV 0.8 1.2 MHz Gm Unity Gain Bandwidth GBW Power Supply Rejection Ratio PSRR 12 ≤ VCC ≤ 18 V 60 70 dB Output Sink Current ICOMPL VFB = 2.7 V; VCOMP = 1.1 V 2 6 mA Output Source Current ICOMPH VFB = 2.3 V; VCOMP = 5 V 0.5 1.0 mA Output Swing High ICOMPH VFB = 2.3 V; RL = 15 Ω to GND 5 5.5 V Output Swing Low ICOMPL VFB = 2.7 V; RL = 15 Ω to VREG ASTEC Semiconductor 87 0.7 1.1 V Primary Side PWM Controller AS2214 Electrical Characteristics (cont’d) Electrical Characteristics are guaranteed over full junction temperature range (0 to 105° C). Ambient temperature must be derated based on power dissipation and package thermal characteristics. Unless otherwise specified, the conditions of test are VCC = 15 V; BOK = 3 V; OV = 0V; RT = 680 Ω; CT = 10 nF. To override UVLO, VCC should be raised above 18 V prior to test. Parameter Symbol Test Condition Min Typ Max 4.90 Unit 5 V Regulator Output Voltage VREG IREG = 1 mA, TJ= 25° C 5.00 5.10 V Line Regulation PSRR 12 ≤ VCC ≤ 18 V 5 15 mV 1≤ IREG ≤ 20mA 5 15 mV 0.2 0.4 mV/°C 5.15 V 25 mV Load Regulation Temperature Stability TCREG Total Output Variation Line, Load,Temperature Long-Term Stability Over 1,000 hrs at 25°C 5 10 ≤ f ≤ 100kHz, TJ = 25°C 50 Output Noise Voltage Maximum Source Current VNOISE 4.85 µV IMAX VREG = 4.8 V 30 120 180 mA FOSC TJ =25°C 108 120 132 kHz 0.2 1 % Oscillator Initial Accuracy 12 ≤ VCC ≤ 18 V Voltage Stability Temperature Stability TCF TMIN ≤ TJ ≤ TMAX Amplitude VOSC VRT/CT peak-to-peak 5 % 1.55 V Upper Trip Point VH 2.80 V Lower Trip Point VL 1.25 V Discharge Current IDSC RT =680 Ω, CT =10nF, TJ =25°C Duty cycle Limit Over-Temperature Shutdown 7.50 8.70 9.50 mA 46 50 54 % TOT °C 140 Soft Start Comparator SS Charge Current ISS VSS ≤ VRAMP -4 -6 VSS = 1 V, VOV > 2.5V 2 8 mA 0.6 V V -10 µA SS Discharge Current IDsc SS SS Lower Clamp VSS Low RAMP High Level VRAMPH TJ =25°C 2.15 RAMP Low Level VRAMPL TJ =25°C 0.6 V Note: RAMP wavefrom is the same as the RT/CT wavefrom, but level shifted down one diode drop -2 mV/°C – 0.2 mA RAMP Levels TC RAMP Sink Current IRAMPL TJ =25°C – 0.1 RAMP Source Current IRAMPH TJ =25°C 1 Propagation Delay to Output tPB mA 85 ASTEC Semiconductor 88 150 ns Primary Side PWM Controller Electrical Characteristics AS2214 (cont’d) Electrical Characteristics are guaranteed over full junction temperature range (0 to 105° C). Ambient temperature must be derated based on power dissipation and package thermal characteristics. Unless otherwise specified, the conditions of test are VCC = 15 V; BOK = 3 V; OV = 0V; RT = 680 Ω; CT = 10 nF. To override UVLO, VCC should be raised above 18 V prior to test. Parameter Symbol Test Condition Min Typ Max Unit BOK UV Threshold VBOK UV VREG = 5 V 2.500 2.537 2.575 V BOK UV Hysteresis Current IHYST BOK VBOK = 2.6 V BOK Input Bias Current IOFF BOK VBOK = 2.4 V Housekeeping 42 50 58 µA 0.1 1.0 µA OV Threshold VOV 2.50 2.80 3.10 V OV Clear Threshold VOVH 3.80 4.00 4.50 V OV Reset Threshold VOVL 1.10 1.75 2.20 V -1 -0.2 1 µA OV Bias Current IBIAS OV VREG = 5 V, VOV ≤ OV Threshold * For Vov > OV Reset Threshold, see characteristic curve ACP Voltage VACP IACP = 10 µA 1.3 V ACP Voltage VACP IACP = -10 µA -1.2 V LEN Charge Current ILEN IACP = 10 µA; VLEN = 0 V -30 -45 -65 µA LEN Charge Current ILEN IACP = -10 µA; VLEN = 0 V -30 -50 -65 µA 3.6 4.5 V Minimum Voltage for LEN Functionality VLEN MIN LEN Logic Reset Voltage VLEN LEN Regeneration Current ILENrgn LEN Clamp VLEN This level reflects one diode drop of hysteresis from VLEN min IACP = 5 µA 5.2 IBIAS LEN VLEN = 5 V, IACP = 0 µA * For LEN input current over full range, see characteristic curve. Transfer Gain AVISNS -0.2 ≤ VISNS ≤ 0.8 V ISNS Level Shift VLS LEN Bias Current 3.0 V -10 µA 5.9 6.6 V µA 8 Current Sense Comparator Maximum Input Signal Power Supply Rejection Ratio VISNS = 0 V 3.00 3.15 1.50 VCOMP =+5 V PSRR 2.85 1.00 12 ≤ VCC ≤ 18 V 1.08 V/V V 1.20 70 V dB Input Bias Current IBIAS -1 -10 µA Propagation Delay to Output tPB 85 150 ns ASTEC Semiconductor 89 Primary Side PWM Controller AS2214 Electrical Characteristics (cont’d) Electrical Characteristics are guaranteed over full junction temperature range (0 to 105° C). Ambient temperature must be derated based on power dissipation and package thermal characteristics. Unless otherwise specified, the conditions of test are VCC = 15 V; BOK = 3 V; OV = 0V; RT = 680 Ω; CT = 10 nF. To override UVLO, VCC should be raised above 18 V prior to test. Parameter Symbol Test Condition Min Typ Max Unit Under Voltage Lockout Startup Threshold VCC (ON) 12.5 14.0 15.8 V Minimum Operating Voltage after Trun-on VCC (OFF) 7.3 8.0 8.5 V Startup Current ICC VCC = 12 V; VACP = VLEN = 0 V Startup Current ICC VCC = 12V; IACP = 5 µA Operating Supply Current ICC 2 10 µA 225 300 µA 12 20 mA 18 V Maximum Operating Supply Voltage VCC Max Output Impedance to GND in UVLO State ZOUT VCC = 6 V 22.0 Output Low Level VOL ISINK = 20 mA 0.1 0.4 V Output Low Level VOL ISINK = 150 mA 1.5 2.2 V Output High Level VOH ISOURCE = 20 mA 13 13.5 V Output High Level VOH ISOURCE = 150 mA 12 13 V kΩ Output Rise Time Fall Time tR CL = 1 nF tF CL = 1 nF Maximum Duty Cycle DMAX 94 Minimum Duty Cycle DMIN 0 50 150 ns 50 150 ns 97 100 % % ASTEC reserves the right to make changes without further notice to any products described herein to improve reliability, function, or design. ASTEC does not assume any liability arising out of the application or use of any product or circuit described herein; neither does it convey any license under its patent rights or the rights of others. ASTEC products are not authorized for use as components in life support devices or systems intended for surgical implant into the body or intended to support or sustain life. Buyer agrees to notify ASTEC of any such intended end use whereupon ASTEC will determine availability and suitability of its products for the intended use. ASTEC and the ASTEC logo are trademarks of ASTEC (BSR) PLC. ASTEC SEMICONDUCTOR 255 Sinclair Frontage Road • Milpitas, California 95035 • Tel. (408) 263-8300 • FAX (408) 263-8340 ASTEC Semiconductor 90