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SI9145 Vishay Siliconix Low-Voltage Switchmode Controller FEATURES D D D D D D 2.7-V to 7-V Input Operating Range Voltage-Mode PWM Control High-Speed, Source-Sink Output Drive (200 mA) Internal Oscillator (up to 2 MHz) Standby Mode 0-100% Controllable Maximum Duty-Cycle DESCRIPTION The SI9145 switchmode controller IC is ideally suited for high efficiency dc/dc converters in low input voltage systems. Operation is guaranteed down to 2.7 V, with a minimum start-up voltage of 3.0 V making the SI9145 ideal for use with NiCd, NMH, and lithium ion battery packs. A mode select pin allows the output driver polarity to be programmed allowing the device to function as a step-up or step-down converter. Features include a precision bandgap reference, a wide bandwidth error amplifier, a 2-MHz oscillator, an input voltage monitor with standby mode and a 200-mA output driver. Supply current in normal operation is typically 1.1 mA and 250 mA in standby mode. The SI9145 implements conventional voltage mode control. The maximum duty cycle in boost mode can be limited by voltage on DMAX/SS pin. Frequency can be externally programmed by selection of ROSC and COSC. The SI9145 is available in both standard and lead (Pb)-free 16-pin SOIC and TSSOP packages and is specified over the industrial temperature range (-25_C to 85_C). FUNCTIONAL BLOCK DIAGRAM 1.5-V Reference Generator VDD UVLOSET UVLO VREF VUVLO ENABLE Temp Sense S OTS R MODE SELECT DMAX/SS COMP Error Amp NI FB + - + - Logic Control Driver VS OUTPUT PGND GND + - COSC ROSC Oscillator Pentiumt is a trademark of Intel Corporation. PowerPCt is a trademark of IBM. Document Number: 70021 S-40710--Rev. K, 19-Apr-04 www.vishay.com 1 SI9145 Vishay Siliconix ABSOLUTE MAXIMUM RATINGS Voltages Referenced to GND. VDD, VS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 V PGND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . "0.3 V VDD to VS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 V Linear Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 V to VDD to +0.3 V Logic Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 V to VDD to +0.3 V Continuous Output Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 mA Storage Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -65 to 125_C Operating Junction Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150_C Power Dissipation (Package)a 16-Pin SOIC (Y Suffix)b . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 900 mW 16-Pin TSSOP (Q Suffix)c . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 925 mW Thermal Impedance (QJA) 16-Pin SOIC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140_C/W 16-Pin TSSOP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135_C/W Notes a. Device mounted with all leads soldered or welded to PC board. b. Derate 7.2 mW/_C above 25_C. c. Derate 7.4 mW/_C above 25_C. RECOMMENDED OPERATING RANGE Voltages Referenced to GND. VDD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.7 V to 7 V VS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.7 V to 7 V fOSC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 kHz to 2 MHz ROSC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 kW to 250 kW COSC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 pF to 200 pF Linear Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 to VDD Digital Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 to VDD VREF Load Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . >150 kW SPECIFICATIONS Test Conditions Unless Otherwise Specifieda Parameter Reference Output Voltage VREF IREF = -10 mA TA = 25_C 1.455 1.477 1.50 1.545 1.523 V Limits B Suffix - 25 to 85_C Symbol 2.7 V v VDD v 7 V, VDD = VS GND = PGND Minb Typ Maxb Unit Oscillator Maximum Frequencyc Accuracy ROSC Voltage Minimum Start-Up Voltage 50% DMAX/SS 100% DMAX/SS DMAX/SS Input Current Voltage Stabilityc g y Temperature Stabilityc fMAX fOSC VROSC VDDOSC VDMAX 50% VDMAX 100% IDMAX MODE SELECT = VDD DMAX = 0 to VDD 2.7 V v VDD v 7 V, Ref to 4.8 V Df/f 2.7 V v VDD v 4.2 V, Ref to 3.5 V 3.8 V v VDD v 5.6 V, Ref to 4.7 V Referenced to 25_C TA = 25_C -100 -16 -8 -7 "5 3.0 1.30 1.58 100 16 8 7 % nA VCC = 3.0 V, COSC = 47 pF, ROSC = 5.0 kW VCC = 3.0 V COSC = 100 pF, ROSC = 6.98 kW TA = 25_C 2.0 0.85 1.0 1.0 V 1.15 MHz www.vishay.com 2 Document Number: 70021 S-40710--Rev. K, 19-Apr-04 SI9145 Vishay Siliconix SPECIFICATIONS Test Conditions Unless Otherwise Specifieda Parameter Symbol 2.7 V v VDD v 7 V, VDD = VS GND = PGND Limits B Suffix - 25 to 85_C Minb Typ Maxb Unit Error Amplifier (COSC = GND, OSC DISABLED) Input Bias Current Open Loop Voltage Gain Offset Voltage Unity Gain Bandwidthc Output Current Power Supply Rejectionc IFB AVOL VOS BW IEA PSRR Source (VFB = 1 V, NI = VREF) Sink (VFB = 2 V, NI = VREF) 2.7 V < VDD < 7.0 V 0.4 VNI = VREF VNI = VREF , VFB = 1.0 V -1.0 47 -15 55 0 10 -2.0 0.8 60 -1.0 15 1.0 mA dB mV MHz mA dB UVLOSET Voltage Monitor Under Voltage Lockout Hysterisis UVLO Input Current VUVLOHL VUVLOLH VHYS IUVLO UVLOSET High to Low UVLOSET Low to High VUVLOLH - VUVLOHL VUVLO = 0 to VDD -100 0.85 1.0 1.2 200 100 1.15 V mV nA Output Output High Voltage Output Low Voltage Peak Output Current Peak Output Current VOH VOL ISOURCE ISINK VDD = 2.7 V, IOUT = -10 mA VDD = 2.7 V, IOUT = 10 mA VDD = 2.7 V, VOUT = 0 V VDD = 2.7 V, VOUT = 2.7 V 150 2.55 2.60 0.06 -180 200 0.15 -130 V mA Logic ENABLE Delay to Output ENABLE Logic Low ENABLE Logic High ENABLE Input Current MODE SELECT Logic Low MODE SELECT Logic High MODE SELECT Input Current tdEN VENL VENH IEN VMODEL VMODEH IMODE MODE SELECT = 0 to VDD 0.8 VDD -1.0 1.0 ENABLE = 0 to VDD 0.8 VDD -1.0 1.0 0.2 VDD ENABLE Rising to OUTPUT 1.5 0.2 VDD ns V mA V mA Over Temperature Sense Trip Point Output Low Voltage Output High Voltage TTRIP VOTSL VOTSH VDD = 2.7 V, IOUT = 1 mA VDD = 2.7 V, IOUT = -1 mA 2.55 150 0.06 2.6 0.15 _C V Supply Supply Current - Normal Mode Supply Current - Standby Mode VDD = 2.7 V, fOSC = 1 MHz, ROSC = 6.98 kW IDD VDD = 7 V, fOSC = 1 MHz, ROSC = 6.98 kW ENABLE = Low 1.1 1.6 250 1.5 2.3 330 mA mA Notes a. CSTRAY < 5 pF on COSC. After Start-Up, VDD of w 3 V. b. The algebraic convention whereby the most negative value is a minimum and the most positive a maximum, is used in this data sheet. c. Guaranteed by design, not subject to production testing. Document Number: 70021 S-40710--Rev. K, 19-Apr-04 www.vishay.com 3 SI9145 Vishay Siliconix TYPICAL CHARACTERISTICS (25_C UNLESS NOTED) 1.515 1.510 1.505 V REF (V) 1.500 1.495 1.490 1.485 2 3 4 5 6 7 8 VDD - Supply Voltage (V) V REF (V) VREF vs. Supply Voltage VREF with 10 mA Load 1.515 1.510 1.505 1.500 1.495 1.490 1.485 -25 VREF vs. Temperature VDD = 3.6 V 0 25 50 75 100 125 t - Temperature (_C) 1.515 1.510 1.505 VREF vs. Load Current 80 60 Error Amplifier Gain and Phase 0 Gain -30 Phase (deg) Phase -60 -90 -120 40 Gain (dB) 5.0 V 2.7, 3.0, 3.6 V 20 0 -20 V REF (V) 1.500 7.0 V 1.495 1.490 1.485 0 5 10 15 20 25 30 VREF - Sourcing Current (mA) -40 0.0001 0.001 0.01 0.1 1 10 100 f - Frequency (MHz) -150 25 Supply Current vs.Supply Voltage and Output Load f = 1 MHz 25 Supply Current vs. Switching Frequency and Output Load VDD = 3.6 V 20 Supply Current (mA) CL = 2,200 pF 20 Supply Current (mA) CL = 2,200 pF 15 900 pF 10 100 pF 5 10 pF 0 2 3 4 5 6 7 15 900 pF 10 5 100 pF 10 pF 0 0.5 1.0 1.5 2.0 VDD - Supply Voltage (V) www.vishay.com Switching Frequency (MHz) Document Number: 70021 S-40710--Rev. K, 19-Apr-04 4 SI9145 Vishay Siliconix TYPICAL CHARACTERISTICS (25_C UNLESS NOTED) Supply Current vs. Frequency and Supply Voltage 5 1.9 CL = 10 pF VDD = 7.0 V 1.7 Normal Current (mA) 5.0 V CL = 10 pF f = 1 MHz Supply Current vs. Supply Voltage and Temperature 4 Supply Current (mA) 1.5 TA = 85_C 25_C -25_C 3 1.3 2 3.6 V 2.7 V 1.1 3.0 V 1 0.0 0.2 0.4 0.6 0.8 1.0 0.9 2.5 3.5 4.5 5.5 6.5 7.5 f - Frequency (MHz) VDD - Supply Voltage (V) Standby Current vs. Supply Voltage and Temperature 270 100 Duty Cycle vs. DMAX/SS Voltage 260 Standby Current (m A) TA = 85_C 80 250 Duty Cycle (%) 25_C 60 240 -25_C 230 40 20 220 2 3 4 5 6 7 VDD - Supply Voltage (V) 1.20 1.15 Switching Frequency (MHz) 1.10 1.05 1.00 0.95 0.90 2 3 4 5 6 7 VDD - Supply Voltage (V) Document Number: 70021 S-40710--Rev. K, 19-Apr-04 0 1.0 1.1 1.2 1.3 DMAX/SS (V) 1.4 1.5 1.6 Switching Frequency vs. Supply Voltage ROSC = 6.98 kW COSC = 100 pF Switching Frequency (MHz) 10.00 Frequency vs. ROSC/COSC 1.00 4.99 kW 12.1 kW 24.9 kW 0.10 49.9 kW 100 kW 249 kW 0.01 40 100 COSC - Capacitance (pF) www.vishay.com 200 300 5 SI9145 Vishay Siliconix TYPICAL CHARACTERISTICS (25_C UNLESS NOTED) Output Rise Time vs. Supply Voltage and Load Output Fall Time vs. Supply Voltage and Load 50 50 40 Output Rise Time (nS) CL = 2,200 pF 30 900 pF 20 100 pF Fall Time (nS) 40 CL = 2,200 pF 30 900 pF 20 10 10 100 pF 10 pF 0 2 3 10 pF 4 5 6 7 0 2 3 4 5 6 7 VDD - Supply Voltage (V) VDD - Supply Voltage (V) 50 Enable Delay to Output 250 UVLO Hysteresis vs. Supply Voltage Mode Select = High 30 UVLO Hysteresis (mV) 6 7 40 Output Delay (nS) 230 210 190 20 Mode Select = Low 170 10 2 3 4 5 VDD - Supply Voltage (V) 150 2 3 4 5 6 7 VDD - Supply Voltage (V) 1.515 1.510 1.505 V REF (V) 1.500 1.495 1.490 1.485 0 VREF vs. Bypass Capacitor VDD = 3.6 V 2 4 6 8 10 Capacitance (mF) www.vishay.com Document Number: 70021 S-40710--Rev. K, 19-Apr-04 6 SI9145 Vishay Siliconix TIMING WAVEFORMS Start-Up (UVLO) ENABLE Normal (Duty Cycle Limit) Standby MODE SELECT 1.2 V UVLOSET 1.0 V ROSC 1.0 V COSC ON OUTPUT OFF >1.5 V DMAX/SS Set for 50% Max. Figure 1. SI9145 Timing Diagram (MODE SELECT = High) Start-Up (UVLO) ENABLE Normal (Duty Cycle Limit) Standby MODE SELECT 1.2 V UVLOSET 1.0 V ROSC 1.0 V COSC OFF OUTPUT ON DMAX/SS Figure 2. SI9145 Timing Diagram (MODE SELECT = Low) Document Number: 70021 S-40710--Rev. K, 19-Apr-04 www.vishay.com 7 SI9145 Vishay Siliconix PIN CONFIGURATIONS SOIC-16 VDD MODE SELECT DMAX/SS COMP FB NI VREF GND 1 2 3 4 5 6 7 8 Top View 16 15 14 13 12 11 10 9 VS OUTPUT PGND UVLOSET ENABLE OTS COSC ROSC VDD MODE SELECT DMAX/SS COMP FB NI VREF GND 1 2 3 4 5 6 7 8 Top View TSSOP-16 16 15 14 13 12 11 10 9 VS OUTPUT PGND UVLOSET ENABLE OTS COSC ROSC ORDERING INFORMATION-SOIC-16 Part Number SI9145BY-T1 SI9145BY-T1--E3 ORDERING INFORMATION-TSSOP-16 Part Number SI9145BQ-T1 SI9145BQ-T1--E3 Temperature Range -25_ to 85_C 25_ Temperature Range -25_ to 85_C 25_ PIN DESCRIPTION Pin 1: VDD The positive power supply for all functional blocks except output driver. A bypass capacitor of 0.1 mF (minimum) is recommended. Pin 2: MODE SELECT This pin is used to enable maximum duty cycle limit and set output polarity of controller. When connected to VDD, the maximum duty cycle function is controlled by the DMAX/SS pin. The maximum duty cycle limit is usually used for forward, flyback, and boost converters. The output polarity is high when the PWM circuitry requires the external device to be turned on. When connected to GND, the maximum duty cycle is not limited (usually for buck converters driving a p-channel MOS). The output polarity is low when the PWM circuitry requires the external PMOS to be turned on. Pin 3: DMAX/SS DMAX/SS pin controls the maximum duty cycle achievable by the PWM circuitry when the MODE SELECT = VDD. When DMAX/SS is at less than 1.0 V (typical) the OUTPUT is held low (0% duty cycle). When DMAX/SS is at more than 1.5 V (typical), the PWM circuitry can achieve 100% duty cycle. With www.vishay.com voltage at DMAX/SS between 1.0 V and 1.5 V, the maximum duty cycle is proportionally limited to this voltage. The addition of external components can implement a soft start function. Pin 4: COMP This pin is the output of the error amplifier. A compensation network is connected from this pin to the FB pin to stabilize the system. This pin drives one input of the internal pulse width modulation comparator. Pin 5: FB The inverting input of the error amplifier. External resistors are connected to this pin to set the regulated output voltage. The compensation network is also connected to this pin. Pin 6: NI The non-inverting input of the error amplifier. In normal operation it is externally connected to the VREF pin. Pin 7: VREF This pin supplies 1.5 V trimmed to "1.5%. The reference voltage is generated by a band-gap reference. Pin 8: GND Negative return for VDD. Document Number: 70021 S-40710--Rev. K, 19-Apr-04 8 SI9145 Vishay Siliconix Pin 9: ROSC This pin is the equivalent of a 1.0-V voltage source derived from the on-chip VREF . When a low T.C. resistor is externally connected from this pin to GND, a temperature independent current is generated internally. This current is used as the charging current source connected to the COSC pin. The current is internally multiplied by 2 and is used as the discharging current source connected to the COSC pin. Therefore, the external resistor is one of the factors that determine the oscillator frequency. Pin 10: COSC An external capacitor is connected to this pin to set the oscillator frequency. Internal current sources alternately charge and discharge the external capacitor. The oscillator waveform is a symmetrical triangular type with a typical voltage swing between 1.0 V and 1.5 V. fOSC ] R 0.7 OSC < C OSC Pin 12: ENABLE A logic high on this pin allows normal operation. A logic low places the chip in the standby mode. In standby mode normal operation is disabled, supply current is reduced, the oscillator stops and the output is held high for MODE SELECT = low, and low for MODE SELECT = high. Pin 13: UVLOSET This pin will place the chip in the standby mode if the UVLOSET voltage drops below 1.2 V. Once the UVLOSET voltage exceeds 1.2 V, the chip operates normally. There is a built-in hysteresis of 200 mV. Pin 14: PGND The negative return for the VS supply. Pin 15: OUTPUT This CMOS push-pull output pin drives the external MOSFET and is capable of sinking 150 mA or sourcing 130 mA with VS equal to 2.7 V. Pin 16: VS The positive terminal of the power supply which powers the CMOS output driver. A bypass capacitor is required. Pin 11: OTS This pin indicates an over-temperature condition on the device when the output is low. The output is latched low and is reset with the ENABLE pin going low then high, or by turning power off and on. Document Number: 70021 S-40710--Rev. K, 19-Apr-04 www.vishay.com 9 SI9145 Vishay Siliconix APPLICATIONS L1 D1 VOUT VDD 2.7 V - 7 V Q1 C1 C2 SI9145 0V Figure 3. Non-Isolated Step Up Boost Converter for VOUT > VIN Q1 L1 VOUT VDD 2.7 V - 7 V C1 C2 SI9145 D1 0V Figure 4. Non-Isolated Step Down Buck Converter for VOUT < VIN VDD 2.7 V - 7 V Q1 C1 L1 SI9145 Q2 C2 VOUT 0V Figure 5. Non-Isolated Synchronous Buck Converter for VOUT < VIN www.vishay.com 10 Document Number: 70021 S-40710--Rev. K, 19-Apr-04 |
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