Si9120 Vishay Siliconix Off-Line Power Si9120 Universal Input Switchmode Controller FEATURES * 10- to 450-V Input Range * Current-Mode Control * 125-mA Output Drive * Internal Start-Up Circuit * Internal Oscillator (1 MHz) * SHUTDOWN and RESET DESCRIPTION The Si9120 is a BiC/DMOS integrated circuit designed for use in low-power, high-efficiency off-line power supplies. High-voltage DMOS inputs allow the controller to work over a wide range of input voltages (10- to 450-VDC). Current-mode PWM control circuitry is implemented in CMOS to reduce quiescent current to less than 1.5 mA. A CMOS output driver provides high-speed switching for MOSFET devices with gate charge, Qg, up to 25 nC, enough to supply 30 W of output power at 100 kHz. These devices, when combined with an output MOSFET and transformer, can be used to implement single-ended power converter topologies (i.e., flyback and forward). The Si9120 is available in a 16-pin plastic DIP and SOIC packages, and is specified over the industrial, D suffix (-40 to 85C) temperature range. FUNCTIONAL BLOCK DIAGRAM Applications information may also be obtained via FaxBack, request document #70580 and #70578. FaxBack 408-970-5600, request 70006 www.siliconix.com S-60752--Rev. F, 05-Apr-99 1 Si9120 Vishay Siliconix ABSOLUTE MAXIMUM RATINGS Voltages Referenced to -VIN (Note: VCC < +VIN + 0.3 V) Power Dissipation (Package)b VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 V 16-Pin Plastic DIP (J Suffix)c . . . . . . . . . . . . . . . . . . . . . . . . . 750 mW +VIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 450 V 16-Pin SOIC (Y Suffix)d . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 900 mW Logic Inputs (RESET SHUTDOWN, OSC IN, OSC OUT). . . . . . . . . . . -0.3 V to VCC + 0.3 V Thermal Impedance (JA) Linear Input 16-Pin SOIC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .140C/W (FEEDBACK, SENSE, BIAS, VREF) . . . . . . . . . . . . . . . . .-0.3 V to 7 V Notes HV Pre-Regulator Input Current (continuous). . . . . . . . . . . . . . .5 mAa 16-Pin Plastic DIP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .167C/W Continuous Output Current (Source or Sink) . . . . . . . . . . . . . 125 mA a. Continuous current may be limited by the applications maximum input voltage and the package power dissipation. Storage Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . -65 to 150C b. Device mounted with all leads soldered or welded to PC board. Operating Temperature. . . . . . . . . . . . . . . . . . . . . . . . . . . -40 to 85C c. Derate 6 mW/C above 25C. Junction Temperature (TJ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150C d. Derate 7.2 mW/C above 25C. RECOMMENDED OPERATING RANGE Voltages Referenced to -VIN ROSC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 k to 1 M VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9.5 V to 13.5 V Linear Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 to VCC - 3 V +VIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10 V to 450 V Digital Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 to VCC fOSC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 kHz to 1 MHz SPECIFICATIONSa Limits Test Conditions Unless Specified Parameter Symbol D Suffix -40 to 85C DISCHARGE = -VIN = 0 V, VCC = 10 V +VIN = 300 V RBIAS = 390 k, ROSC = 330 k Tempb Minc Typd Maxc Unit OSC IN = - VIN (OSC Disabled) RL = 10 M Room Full 3.88 3.82 4.0 4.12 4.14 V Room 15 30 45 k Room 70 100 130 A 0.5 1.0 mV/C Reference Output Voltage VR Output Impedancee ZOUT Short Circuit Current ISREF Stabilitye TREF Maximum Frequencye fMAX Initial Accuracy fOSC Temperature VREF = -VIN Full Oscillator f/f Voltage Stability Temperature Coefficiente ROSC = 0 Room 1 3 MHz CSTRAY Pin 9 5 pF, ROSC = 330 k Room 80 100 120 CSTRAY Pin 9 5 pF, ROSC = 150 k Room 160 200 240 f/f = f(13.5 V) - f(9.5 V) / f(9.5 V) Room 10 15 % Full 200 500 ppm/C 4.08 V 25 500 nA 15 40 mV TOSC kHz Error Amplifier Feedback Input Voltage VFB FB Tied to COMP OSC IN = - VIN (OSC Disabled) Room Input BIAS Current IFB OSC IN = - VIN, VFB = 4 V Room Input OFFSET Voltage VOS OSC IN = - VIN Room Open Loop Voltage Gaine AVOL OSC IN = - VIN Room 60 1.0 e BW OSC IN = - VIN Room Dynamic Output Impedancee ZOUT Error Amp configured for 60 dB gain Room Output Current IOUT Unity Gain Bandwidth Power Supply Rejection S-60752--Rev. F, 05-Apr-99 2 PSRR 3.92 80 dB 1.5 MHz 1000 2000 -2.0 -1.4 Source VFB = 3.4 V Room Sink VFB = 4.5 V Room 0.12 0.15 9.5 V VCC 13.5 V Room 50 70 mA dB FaxBack 408-970-5600, request 70006 www.siliconix.com Si9120 Vishay Siliconix SPECIFICATIONSa Limits Test Conditions Unless Specified Parameter D Suffix -40 to 85C Symbol DISCHARGE = -VIN = 0 V, VCC = 10 V +VIN = 300 V RBIAS = 390 k, ROSC = 330 k Tempb Minc Typd Maxc Unit VSOURCE VFB = 0 V Room 1.0 1.2 1.4 V td VSENSE = 1.5 V, See Figure 1. Room 100 150 ns 10 A Current Limit Threshold Voltage Delay to Outpute Pre-regulator/Start-up Input Voltagef +VIN IIN = 10 A Room Input Leakage Current +IIN VCC 9.4 V Room VCC Pre-Regulator Turn-Off Threshold Voltage VREG IPRE-REGULATOR = 10 A Room 7.8 8.6 9.4 Undervoltage Lockout VUVLO Room 7.0 8.1 8.9 VREG -VUVLO VDELTA Room 0.3 0.6 450 V V Supply Supply Current Bias Current ICC CL = 500 pF at Pin 5 Room Room IBIAS 10 0.85 1.5 mA 15 20 A 50 100 Logic SHUTDOWN Delaye tSD CL = 500 pF, VSENSE = -VIN See Figure 2. Room SHUTDOWN Pulse Widthe tSW Room 50 RESET Pulse Widthe tRW Room 50 tLW Room 25 Latching Pulse Width SHUTDOWN and RESET Lowe ns See Figure 3. Input Low Voltage VIL Room Input High Voltage VIH Room 2.0 Input Current Input Voltage High IIH VIN = 10 V Room Input Current Input Voltage Low IIL VIN = 0 V Room -35 Output High Voltage VOH IOUT = -10 mA Room Full 9.7 9.5 Output Low Voltage VOL IOUT = 10 mA Room Full Output Resistance ROUT IOUT = 10 mA, Source or Sink Room Full 20 25 30 50 Room 40 75 8.0 1 V 5 A -25 Output Rise Time Fall Time e e tr tf CL = 500 pF Room 0.3 0.5 40 75 V ns Notes a. Refer to PROCESS OPTION FLOWCHART for additional information. b. Room = 25C, Cold and Hot = as determined by the operating temperature suffix. c. The algebraic convention whereby the most negative value is a minimum and the most positive a maximum, is used in this data sheet. d. Typical values are for DESIGN AID ONLY, not guaranteed nor subject to production testing. e. Guaranteed by design, not subject to production test. f. 250V +VIN 380V place a 10 k, 1/4 W resistor in series with +VIN (Pin 1). 380V +VIN 450V place a 15 k, 1/4 W resistor in series with +VIN (Pin 1). Connect a 0.01 d capacitor between +VIN (Pin 1) and -VIN (Pin 6). FaxBack 408-970-5600, request 70006 www.siliconix.com S-60752--Rev. F, 05-Apr-99 3 Si9120 Vishay Siliconix TIMING WAVEFORMS FIGURE 1. FIGURE 2. FIGURE 3. TYPICAL CHARACTERISTICS FIGURE 4. S-60752--Rev. F, 05-Apr-99 4 FaxBack 408-970-5600, request 70006 www.siliconix.com Si9120 Vishay Siliconix PIN CONFIGURATIONS Top View Top View Order Number: Si9120DJ Order Number: Si9120DY Note: Pins 2 and 3 are removed DETAILED DESCRIPTION Pre-Regulator/Start-Up Section BIAS Due to the low quiescent current requirement of the Si9120 control circuitry, bias power can be supplied from the unregulated input power source, from an external regulated low-voltage supply, or from an auxiliary "bootstrap" winding on the output inductor or transformer. To properly set the bias for the Si9120, a 390-k resistor should be tied from BIAS (pin 16) to -VIN (pin 6). This determines the magnitude of bias current in all of the analog sections and the pull-up current for the SHUTDOWN and RESET pins. The current flowing in the bias resistor is nominally 15 A. When power is first applied during start-up, +VIN (pin 1) will draw a constant current. The magnitude of this current is determined by a high-voltage depletion MOSFET which is connected between +VIN and VCC (pin 7). This start-up circuitry provides initial power to the IC by charging an external bypass capacitance connected to the VCC pin. The constant current is disabled when VCC exceeds 8.6 V. If VCC is not forced to exceed the 8.6-V threshold, then VCC will be regulated to a nominal value of 8.6 V by the pre-regulator circuit. As the supply voltage rises toward the normal operating conditions, an internal undervoltage (UV) lockout circuit keeps the output driver disabled until VCC exceeds the undervoltage lockout threshold (typically 8.1 V). This guarantees that the control logic will be functioning properly and that sufficient gate drive voltage is available before the MOSFET turns on. The design of the IC is such that the undervoltage lockout threshold will be at least 300 mV less than the pre-regulator turn-off voltage. Power dissipation can be minimized by providing an external power source to VCC such that the constant current source is always disabled. Note: When driving large MOSFETs at high frequency without a bootstrap VCC supply, power dissipation in the pre-regulator may exceed the power rating of the IC package. For operation of +VIN > 250V a 10 k, 1/4 W resistor should be placed in series with +VIN (Pin 1). For +VIN > 380V a 15 k, 1/4 W resistor is recommended. FaxBack 408-970-5600, request 70006 www.siliconix.com Reference Section The reference section of the Si9120 consists of a temperature compensated buried zener and trimmable divider network. The output of the reference section is connected internally to the non-inverting input of the error amplifier. Nominal reference output voltage is 4 V. The trimming procedure that is used on the Si9120 brings the output of the error amplifier (which is configured for unity gain during trimming) to within 2% of 4 V. This compensates for input offset voltage in the error amplifier. The output impedance of the reference section has been purposely made high so that a low impedance external voltage source can be used to override the internal voltage source, if desired, without otherwise altering the performance of the device. Error Amplifier Closed-loop regulation is provided by the error amplifier, which is intended for use with "around-the-amplifier" compensation. A MOS differential input stage provides for high input impedance. The noninverting input to the error amplifier (VREF) is internally connected to the output of the reference supply and should be bypassed with a small capacitor to ground. S-60752--Rev. F, 05-Apr-99 5 Si9120 Vishay Siliconix Oscillator Section The oscillator consists of a ring of CMOS inverters, capacitors, and a capacitor discharge switch. Frequency is set by an external resistor between the OSC IN and OSC OUT pins. (See Typical Characteristics for details of resistor value vs. frequency.) The DISCHARGE pin should be tied to -VIN for normal internal oscillator operation. A frequency divider in the logic section limits switch duty cycle to 50% by locking the switching frequency to one half of the oscillator frequency. open-collector driver to the SHUTDOWN or RESET pins to provide variable shutdown time. TABLE 1. Truth Table for SHUTDOWN and RESET Pins SHUTDOWN RESET H H Normal Operation L H Off (Not Latched) L L Off (Latched) L Off (Latched, No Change) H SHUTDOWN and RESET SHUTDOWN (pin 12) and RESET (pin 13) are intended for overriding the output MOSFET switch via external control logic. The two inputs are fed through a latch preceding the output switch. Depending on the logic state of RESET. SHUTDOWN can be either a latched or unlatched input. The output is off whenever SHUTDOWN is low. By simultaneously having SHUTDOWN and RESET low, the latch is set and SHUTDOWN has no effect until RESET goes high. See Table 1. Both pins have internal current source pull-ups and should be left disconnected when not in use. An added feature of the current sources is the ability to connect a capacitor and an S-60752--Rev. F, 05-Apr-99 6 Output Normal Operation (No Change) Output Driver The push-pull driver output has a typical on-resistance of 20- maximum switching times are specified at 75 ns for a 500-pF load. This is sufficient to directly drive MOSFETs such as the IRF820, BUZ78 or BUZ80. Larger devices can be driven, but switching times will be longer, resulting in higher switching losses. For applications information refer to AN707 (FaxBack #70580) and AN708 (FaxBack #70581). FaxBack 408-970-5600, request 70006 www.siliconix.com