LV56351HA DC/DC Boost converter for BS/CS antennas Application Note http://onsemi.com Ver.2.0 1. Overview LV56351HA integrates 1ch DC/DC boost converter and 1ch LDO. It is suitable as the power supply for BS/CS antennas of LCD/PDP TV and BD recorders that require automatic recovery without IC destruction and malfunction when the output is short-circuited. 2. Function DC/DC boost converter Soft-start time: 2.8ms Pulse by pulse over-current limiter LDO Over-current limiter (Fold back) ALL Under-voltage lockout Power good Frequency 425kHz operation Short circuit protector Thermal shut-down protector 3. Block diagram and Application circuit VCC=12V C1 VCC DC/DC OUT (LDOIN) DC/DC OUT VREF R2 D1 C7 R1 VREG SW C5 R6 L1 DC/DC Boost Converter C2 IN1 R5 Soft Start C6 OSC P by P FB LDOIN SCP C4 PGOOD V1 High Enable LDOOUT R7 PGOOD SCP UVLO TSD EN DDCTL DC/DC Control LDOOUT ILimit IO=300mA IN2 R4 C3 R3 LDO SGND PGND Figure 1: Block diagram and Application circuit Semiconductor Components Industries, LLC, 2013 December, 2013 1/11 LV56351HA Application Note 4. Evaluation Board Figure 2: Evaluation Board 4.1 Performance summary VCC input LDOOUT output Oscillation Frequency EN input 12V 16.5V 425kHz High(2V): IC ON Low(0V): IC OFF V1 input 2V DDCTL state * Open or Low(0V) *About DDCTL: When DDCTL pin is Open or Low, Evaluation Board operates normally. If DDCTL pin is high, DC-DC converter operation is compulsorily stopped and only LDO operates. When DDCTL becomes Open or Low from High, LDO stops temporarily and DC-DC boost converter starts with soft start and then LDO restart. 2/11 LV56351HA Application Note 4.2 Schematic VCC=12V F1 C1 10uF/ 25V LDOIN (DC/DCOUT) C5 R2 0.1uF R6 5.1k 240k C7 43k 12 L1 VCC 22uH NRS5040T 220MMGK 5 R8 D1 IN1 SB1003M3 C2 LV56351HA R5 R1 Open LDOIN (DC/DCOUT) =17.5V SW 220pF 6.8k 10uF/ 35V 22k C6 Tr1 3900pF 6 FB 9 SCP Open SCP C4 LDOIN 0.01uF 8 V1 R7 LDOOUT =16.5V LDOOUT PGOOD R4 10k PGOOD 82k EN 11 EN DDCTL 10 DDCTL 39k SGND PGND 7 Fin C3 4.7uF/ 4.7uF/ 25V 25V IN2 R9 R3 Open LDO 10k 15V/11V CTL DC/DC Boost Converter Tr2 Tr1 Gate & Tr2 Gate Open Open (It is not used) Figure 3: Schematic of Evaluation Board 4.3 Bill of Materials Designator Quantity C1 1 C2 1 C3 2 C4 1 C5 1 C6 1 C7 1 D1 1 F1 1 L1 1 R1 1 1 R2 1 R3 1 1 R4 1 R5 1 R6 1 R7 1 R8 R9 U1 1 Tr1 Tr2 - Description Capacitor,Ceramic,B Capacitor,Ceramic,X7R Capacitor,Ceramic,B Capacitor,Ceramic,B Capacitor,Ceramic,B Capacitor,Ceramic,SL Capacitor,Ceramic,CH Diode,Schottky Fuse Resistor Power Inductor Chip Resistor Chip Resistor Chip Resistor Chip Resistor Chip Resistor Chip Resistor Chip Resistor Chip Resistor Chip Resistor DNP DNP DCDC and LDO Driver DNP DNP Value 10uF/25V 10uF/35V 4.7uF/25V 0.01uF/50V 0.1uF/50V 3900p/50V 220pF/50V 30V/1A 3.15A 22uH 22k 240k 43k 10k 82k 39k 6.8k 5.1k 10k DNP DNP DNP DNP Tolerance 10% 10% 10% 10% 10% 5% 5% 20% 1% 1% 1% 1% 1% 1% 1% 1% 1% - Footprint 1206 1210 1206 0603 0603 0603 0603 MCPH3 0603 4.9x4.9 0603 0603 0603 0603 0603 0603 0603 0603 0603 HSSOP-14 - Manufacturer MURATA MURATA MURATA MURATA MURATA MURATA MURATA ON Semiconductor KOA TAIYO YUDEN KOA KOA KOA KOA KOA KOA KOA KOA KOA ON Semiconductor - Manufacturer Part Number GRM31CB31E106K GRM32ER7YA106K GRM31CB31E475K GRM188B11H103K GRM188B31H104K GRM1881X1H392JA01J GRM1882C1H221J SB1003M3 TF16AT3.15TBK NRS5040T 220MMGK RK73H1JTTD223 RK73H1JTTD244 RK73H1JTTD433 RK73H1JTTD103 RK73H1JTTD823 RK73H1JTTD393 RK73H1JTTD682 RK73H1JTTD512 RK73H1JTTD103 DNP DNP LV56351HA DNP DNP 3/11 LV56351HA Application Note 4.4 Test Procedure Suggested equipment: Current limited DC Power Supply (e.g. ADVANTEST R6243 DC Voltage Current Source/Monitor) ···· 2pcs Digital Multimeter (e.g. ADVANTEST R6452 Digital Multimeter) ················································· 2pcs Multifunction Generator (e.g. NF WF1974) ············································································ 1pc Electronic Load (e.g. FUJITSU ACCESS LIMITED Electric Load EUL-150αXL) ···························· 1pc Oscilloscope (e.g. LeCroy WaveRunner) ·············································································· 1pc PGOOD SCP 2V Current limited DC Power Supply V1 LDOIN Hi Multifunction Generator + - EN Digital Multimeter Lo LDOOUT VCC IO Current limited DC Power Supply 12V + Electronic Load - + - Digital Multimeter GND Figure 4: Test setup Procedure: (1) Connect the test setup as shown in Figure 4 (2) Apply 12Vdc to VCC. (3) Apply 2Vdc to V1. (4) Apply Low level (0V) signal to EN. (5) Check that LDOIN=0[V] and LDOOUT=0[V]. (6) Apply IO(load)=0[A] to LDOOUT. (7) Apply High level (2V) signal to EN. (8) Check that LDOIN=17.5[V] and LDOOUT=16.5[V] (9) Set IO to desired level, 0[mA] – 300[mA], and measure LDOOUT voltage and LDOIN voltage. (10) Apply Low level signal to EN. (11) Turn off IO(load). (12) Turn off VCC, V1, and EN. 4/11 LV56351HA Application Note 4.5 Reference data (Ta=25˚C, VCC=12V, V1=2V) Line Regulation (Load from LDOOUT) LDOIN (DC-DC boost converter output) LDOOUT LDOIN-VCC LDOOUT-VCC 18.0 17.0 IO=0A IO=0A IO=300mA LDOOUT [V] LDOIN [V] IO=300mA 17.5 17.0 16.5 16.0 8 9 10 11 12 13 14 15 16 17 8 9 10 11 12 13 14 15 16 17 VCC [V] VCC [V] Load Regulation (Load from LDOOUT) LDOIN (DC-DC boost converter output) LDOOUT LDOIN-IO LDOOUT-IO 17.0 LDOOUT [V] LDOIN [V] 18.0 17.5 17.0 16.5 16.0 0 50 100 150 IO [mA] 200 250 300 0 50 100 150 200 250 300 IO [mA] 5/11 LV56351HA Application Note Output waveform IO=0A(LDOOUT load) IO=270mA(LDOOUT load) LDOIN (DC-DC output) [20mV/div] LDOIN (DC-DC output) [20mV/div] LDOOUT [20mV/div] LDOOUT [20mV/div] Time 1us/div Time 1us/div Start-up and Stop waveform VCC=12V, IO=270mA(LDOOUT load) Start-up Stop EN [2V/div] EN [2V/div] LDOIN (DC-DC output) [5V/div] LDOOUT [5V/div] LDOOUT [5V/div] LDOIN (DC-DC output) [5V/div] Time 1ms/div Time 1ms/div LDO current limit operation [ Output setting: LDOIN=16V, LDOOUT=15V ] LDOOUT-IO 20 LDOOUT [V] 15 10 Ta=-40℃ Ta=25℃ Ta=85℃ Ta=125℃ 5 0 0 200 400 600 IO [mA] 6/11 LV56351HA Application Note Load transient response (Load from LDOOUT) LDOOUT load =50mA↔270mA Load=270mA IO(load) [0.2A/div] Load=50mA LDOOUT [0.2V/div] Time 50us/div IO fall time: 200ns IO rise time: 200ns Short Circuit Protection (SCP) (Over load from LDOIN (DC-DC output) ) Load from LDOIN (DC-DC output) [1A/div] LDOIN (DC-DC output) [5V/div] FB [0.5V/div] VREF=1.26V SCP [0.2V/div] Time 1ms/div TSCP = 2.6ms Over load Latched off PGOOD operation PGOOD→ High (Output fault) LDOIN (DC-DC output) [5V/div] PGOOD→ Low (Output good) LDOIN (DC-DC output) [5V/div] LDOOUT [5V/div] PGOOD [1V/div] LDOOUT [5V/div] PGOOD [1V/div] 7/11 LV56351HA Application Note 4.6 Board Layout Top-Side Bottom-Side Board size: 63.0mm×38.5mm 8/11 LV56351HA Application Note 5. Detailed description 5.1 Output voltage setting DC/DC output (LDOIN) “DC/DC boost converter output (LDOIN)” and “LDOOUT” are given by the following expressions. LDOIN = R1+R2 × VREF R1 LDOOUT = R2 R3+R4 × VREF R3 IN1 R4 IN2 R1 where, VREF = 1.26 V (typical) LDOOUT R3 5.2 Start-up and Stop Diagram Softstart 2.8ms DC/DC boost output (LDOIN) LDO output (LDOOUT) 17.5V 16.5V 12V(=VCC) 5ms 0V 500us Time Delay for initialization EN 5.2 Short Circuit Protection (SCP) time setting When the output voltage of DC/DC boost converter decreases due to short circuit; for example, SCP function latches off the outputs of DC/DC and LDO by timer. To define SCP time (TSCP), you need to calculate a value of SCP capacitor (C4) using the following formula. TSCP = C4 × VREF ISCP where, ISCP = 4.8 uA (typical) 9/11 LV56351HA Application Note 5.3 Inductor In DCDC boost converter, the current as IL shown in the figure on the right-hand side flows through inductor. DCDC boost converter output voltage ΔIL IL_AVG ΔIL (VOUT) is given by the following expression. VIN VOUT = 1 - D where, VIN : Input voltage t D : Power MOSFET ON Duty, D = Ton T Ton : Power MOSFET ON Time Ton Toff Ton : Switching On Time Toff : Switching Off Time T =1/fOSC 1 T : Switching period, T = f OSC fOSC : Switching frequency = 1 MHz (typical) Ripple current of the inductor (ΔIL) is given by the following expression. VIN × D VIN × Ton ΔIL = 2 × L × f = 2×L OSC where, L : Inductance value of L1 At the maximum output load (IOmax), the peak of the inductor current (ILpeak) is given by ILpeak = IL_AVG[max] + ΔIL where, IL_AVG[max] : The average of inductor current at the maximum output load Select an inductor (L1) which can permit ILpeak. If ΔIL is higher than the average inductor current, the mode is switched to Discontinuous Mode. 5.3 Input capacitor RMS ripple current of the input capacitor (C1,C5) is given by Irms(Cin) = 1 VIN × D × 2 3 L × fOSC Select the input capacitor which can be low ESR and enough capacitance value to supply the stable voltage to VCC pin. 5.4 Output capacitor for DCDC boost converter RMS ripple current of the output capacitor (C2) for DCDC boost converter is given by Irms(Cout) ≈ IO × VOUT - VIN VIN where, IO : Output load When VIN is minimum and IO is maximum, Irms(Cout) is maximum. Select the output capacitor which can permit the maximum Irms(Cout). Use the capacitor which has enough margin to the maximum rating. 10/11 LV56351HA Application Note 5.5 Rectifier diode for DCDC boost converter Use the Schottky Diode as rectifier diode for DCDC boost converter. Make sure that the diode meets the following 3 conditions: 1) rated reverse voltage of the diode is higher than output voltage, 2) rated average current is higher than maximum load current and 3) rated surge forward current is higher than peak inductor current. 5.6 Phase compensation for DCDC boost converter To stabilize DCDC boost converter by phase compensation, you need to cancel double pole (-180deg) caused by LC with 2 zeros (+90deg ×2). Set the frequency of 2 zeros near the LC resonance frequency. DCDC OUT (LDOIN) VCC R5 C7 C6 L1 SW R2 DCDC OUT IN1 － C2 VREF ＋ FB PWM Comp. R1 Error Amp. 【LC resonance frequency】 1 fr = [Hz] 2π× L1×C2 【Zero】 1 [Hz] 2π× C5×RA 1 fz2 = [Hz] 2π× C6×R2 fz1 = 11/11