Hi-performance Regulator IC Series for PCs Nch FET Ultra LDOs for Desktop PCs BD3523HFN, BD35230HFN, BD35231HFN No.09030EBT01 Description The BD3523HFN, BD35230HFN, BD35231HFN ultra low-dropout linear chipset regulator operates from a very low input supply, and offers ideal performance in low input voltage to low output voltage applications. It incorporates a built-in N-MOSFET power transistor to minimize the input-to-output voltage differential to the ON resistance (RON=150m) level. By lowering the dropout voltage in this way, the regulator realizes high current output (Iomax=2.0A) with reduced conversion loss, and thereby obviates the switching regulator and its power transistor, choke coil, and rectifier diode. Thus, the BD3523HFN, BD35230HFN, BD35231HFN designed to enable significant package profile downsizing and cost reduction. In BD3523HFN, an external resistor allows the entire range of output voltage configurations between 0.65 and 2.7V, while the NRCS (soft start) function enables a controlled output voltage ramp-up, which can be programmed to whatever power supply sequence is required. Features 1) Internal high-precision reference voltage circuit(0.65V1%) 2) Internal high-precision output voltage circuit 3) Built-in VCC undervoltage lockout circuit (VCC=3.80V) 4) NRCS (soft start) function reduces the magnitude of in-rush current 5) Internal Nch MOSFET driver offers low ON resistance (100m typ) 6) Built-in short circuit protection (SCP) 7) Built-in current limit circuit (2.0A min) 8) Built-in thermal shutdown (TSD) circuit 9) Variable output (0.652.7V) 10) High-power package HSON8 : 2.9mmx3.0mmx0.6mm 11) Tracking function Applications Notebook computers, Desktop computers, LCD-TV, DVD, Digital appliances Line-up Maximum Output Voltage Adjustable (0.652.7V) 1.0V (fixed) 1.2V (fixed) www.rohm.com (c) 2009 ROHM Co., Ltd. All rights reserved. Package HSON8 1/20 Product name BD3523HFN BD35230HFN BD35231HFN 2009.04 - Rev.B Technical Note BD3523HFN, BD35230HFN, BD35231HFN Absolute maximum ratings Parameter Limit Symbol Input Voltage 1 Input Voltage 2 BD3523HFN BD35230HFN Unit VCC +6.0 *1 V VIN *1 V +6.0 *1 IO Maximum Output Current BD35231HFN 2 A -0.3+6.0 V Enable Input Voltage VEN Power Dissipation 1 Pd1 0.63 *2 W Power Dissipation 2 Pd2 1.35 *3 W *4 W Power Dissipation 3 Pd3 Operating Temperature Range Topr -10+100 Storage Temperature Range Tstg -55+125 Tjmax +150 Maximum Junction Temperature 1.75 *1 Should not exceed Pd. *2 Reduced by 5.04mW/ for each increase in Ta25 (when mounted on a 70mmx70mmx1.6mm glass-epoxy board, 1-layer, copper foil area : less than 0.2%) *3 Reduced by 10.8mW/ for each increase in Ta25 (when mounted on a 70mmx70mmx1.6mm glass-epoxy board, 1-layer, copper foil area : less than 7.0%) *4 Reduced by 14.0mW/ for each increase in Ta25 (when mounted on a 70mmx70mmx1.6mm glass-epoxy board, 1-layer, copper foil area : less than 65.0%) Operating Voltage(Ta=25) Parameter Symbol BD3522EFV Min. Max. BD35221EFV Min. Max. BD35222EFV Min. Max. Unit Input Voltage 1 VCC 4.3 5.5 4.3 5.5 4.3 5.5 V Input Voltage 2 VIN 0.95 VCC-1 *5 1.3 VCC-1 *5 1.5 VCC-1 *5 V Output Voltage Setting Range IO VFB 2.7 VEN -0.3 5.5 -0.3 5.5 -0.3 5.5 V CNRCS 0.001 1 0.001 1 0.001 1 F Enable Input Voltage NRCS Capacity 1.0 (fixed) 1.2 (fixed) V *5 VCC and VIN do not have to be implemented in the order listed. *This product is not designed for use in radioactive environments. www.rohm.com (c) 2009 ROHM Co., Ltd. All rights reserved. 2/20 2009.04 - Rev.B Technical Note BD3523HFN, BD35230HFN, BD35231HFN Electrical Characteristics BD3523HFN (Unless otherwise specified, Ta=25, VCC=5V, VEN=3V, VIN=1.7V, R1=3.9k, R2=3.3k) Parameter Symbol Limit Min. Typ. Max. Unit Bias Current ICC - 0.7 1.2 mA VCC Shutdown Mode Current IST - 0 10 A Output Voltage IO 2.0 Condition VEN=0V - - A Feedback Voltage 1 VFB1 0.643 0.650 0.657 V Feedback Voltage 2 VFB2 0.637 0.650 0.663 V Line Regulation 1 Reg.l1 - 0.1 0.5 %/V VCC=4.3V to 5.5V Line Regulation 2 Reg.l2 - 0.1 0.5 %/V VIN=1.2V to 3.3V Load Regulation Reg.L - 0.5 10 mV IO=0 to 2A Tj=-10 to 100 Output ON Resistance RON - 100 150 m IO=2A,VIN=1.2V, Tj=-10 to 100 Standby Discharge Current IDEN 1 - - mA VEN=0V, VO=1V Enable Pin Input Voltage High ENHIGH 2 - - V Enable Pin Input Voltage Low ENLOW 0 - 0.8 V IEN - 7 10 A IFB -100 0 100 nA NRCS Charge Current INRCS 12 20 28 A NRCS Standby Voltage VSTB - 0 50 mV VCCUVLO 3.5 3.8 4.1 V VCChys 100 160 220 mV VINUVLO 0.55 0.65 0.75 V VOSCP VOx0.3 VOx0.4 VOx0.5 V TSCP 45 90 200 sec [ENABLE] Enable Input Bias Current VEN=3V [FEEDBACK] Feedback Pin Bias Current [NRCS] [UVLO] VCC Undervoltage Lockout Threshold Voltage VCC Undervoltage Lockout Hysteresis Voltage VINUndervoltage Lockout Threshold Voltage [SCP] SCP Start up Voltage SCP Threshold Voltage www.rohm.com (c) 2009 ROHM Co., Ltd. All rights reserved. 3/20 VEN=0V VCC:Sweep-up VCC:Sweep-down VIN:Sweep-up 2009.04 - Rev.B Technical Note BD3523HFN, BD35230HFN, BD35231HFN Electrical Characteristics BD35230HFN (Unless otherwise specified, Ta=25, VCC=5V, VEN=3V, VIN=1.7V) Limit Parameter Symbol Unit Min. Typ. Max. Bias Current ICC - 0.7 1.2 mA VCC Shutdown Mode Current IST - 0 10 A Output Voltage Condition VEN=0V IO 2.0 - - A Feedback Voltage 1 VOS1 0.990 1.000 1.010 V Feedback Voltage 2 VOS2 0.980 1.000 1.020 V Line Regulation 1 Reg.l1 - 0.1 0.5 %/V VCC=4.3V to 5.5V Line Regulation 2 Reg.l2 - 0.1 0.5 %/V VIN=1.3V to 3.3V Load Regulation Reg.L - 0.5 10 mV IO=0 to 2A Tj=-10 to 100 Output ON Resistance RON - 100 150 m IO=2A,VIN=1.0V, Tj=-10 to 100 Standby Discharge Current IDEN 1 - - mA VEN=0V, VO=1V Enable Pin Input Voltage High ENHIGH 2 - - V Enable Pin Input Voltage Low ENLOW 0 - 0.8 V IEN - 7 10 A NRCS Charge Current INRCS 12 20 28 A NRCS Standby Voltage VSTB - 0 50 mV VCCUVLO 3.5 3.8 4.1 V VCCHYS 100 160 220 mV VINUVLO 0.60 0.70 0.80 V VOSCP VOx0.3 VOx0.4 VOx0.5 V TSCP 45 90 200 sec [ENABLE] Enable Input Bias Current VEN=3V [NRCS] [UVLO] VCC Undervoltage Lockout Threshold Voltage VCC Undervoltage Lockout Hysteresis Voltage VIN Undervoltage Lockout Threshold Voltage [SCP] SCP Start up Voltage SCP Threshold Voltage www.rohm.com (c) 2009 ROHM Co., Ltd. All rights reserved. 4/20 VEN=0V VCC:Sweep-up VCC:Sweep-down VIN:Sweep-up 2009.04 - Rev.B Technical Note BD3523HFN, BD35230HFN, BD35231HFN Electrical Characteristics BD35231HFN(Unless otherwise specified, Ta=25, VCC=5V, VEN=3V, VIN=1.7V) Limit Parameter Symbol Unit Min. Typ. Max. Bias Current ICC - 0.7 1.2 mA VCC Shutdown Mode Current IST - 0 10 A Output Voltage Condition VEN=0V IO 2.0 - - A Feedback Voltage 1 VOS1 1.188 1.200 1.212 V Feedback Voltage 2 VOS2 1.176 1.200 1.224 V Line Regulation 1 Reg.l1 - 0.1 0.5 %/V VCC=4.3V to 5.5V Line Regulation 2 Reg.l2 - 0.1 0.5 %/V VIN=1.5V to 3.3V Load Regulation Reg.L - 0.5 10 mV IO=0 to 2A Tj=-10 to 100 Output ON Resistance RON - 100 150 m IO=2A,VIN=1.2V, Tj=-10 to 100 Standby Discharge Current IDEN 1 - - mA VEN=0V, VO=1V Enable PinInput Voltage High ENHIGH 2 - - V Enable PinInput Voltage Low ENLOW 0 - 0.8 V IEN - 7 10 A NRCS Charge Current INRCS 12 20 28 A NRCS Standby Voltage VSTB - 0 50 mV VCCUVLO 3.5 3.8 4.1 V VCCHYS 100 160 220 mV VINUVLO 0.72 0.84 0.96 V VOSCP VOx0.3 VOx0.4 VOx0.5 V TSCP 45 90 200 sec [ENABLE] Enable Input Bias Current VEN=3V [NRCS] [UVLO] VCC Undervoltage Lockout Threshold Voltage VCC Undervoltage Lockout Hysteresis Voltage VIN Undervoltage Lockout Threshold Voltage [SCP] SCP Start up Voltage SCP Threshold Voltage www.rohm.com (c) 2009 ROHM Co., Ltd. All rights reserved. 5/20 VEN=0V VCC:Sweep-up VCC:Sweep-down VIN:Sweep-up 2009.04 - Rev.B Technical Note BD3523HFN, BD35230HFN, BD35231HFN Reference Data BD35231HFN Vo 50mV/div Vo 50mV/div 66mV Vo 50mV/div 91mV 108mV 2A Io 2A/div Io 2A/div Io 2A/div 2A T(10sec/div) T(10sec/div) Fig.1 Transient Response (0A2A) Co=100F Cfb=1000pF Vo 50mV/div Io 2A/div Io 2A/div 2A T(10sec/div) Fig.2 Transient Response (0A2A) Co=47F Cfb=1000pF Vo 50mV/div 51mV 2A Fig.3 Transient Response (0A2A) Co=22F Cfb=1000pF Vo 50mV/div 80mV Io 2A/div 2A T(10sec/div) T(10sec/div) 2A T(10sec/div) Fig.5 Transient Response (2A0A) Co=47 Cfb=1000pF Fig.4 Transient Response (2A0A) Co=100F Cfb=1000pF 98mV Fig.6 Transient Response (2A0A) Co=22 Cfb=1000pF VCC Ven Ven VNRCS VNRCS Vo Vo Ven VIN Vo T(200sec/div) T(200sec/div) Fig.7 Waveform at output start VCCVINVen Fig.8 Waveform at output OFF Fig.9 Input sequence VCC VCC VCC Ven Ven Ven VIN VIN VIN Vo Vo Vo VINVCCVen Fig.10 Input sequence www.rohm.com (c) 2009 ROHM Co., Ltd. All rights reserved. VenVCCVIN Fig.11 Input sequence 6/20 VCCVenVIN Fig.12 Input sequence 2009.04 - Rev.B Technical Note BD3523HFN, BD35230HFN, BD35231HFN Reference Data BD35231HFN 1.25 VCC 1.23 Ven Ven 1.21 VIN VIN Vo Vo Vo [V] VCC 1.19 1.17 1.15 VINVenVCC VenVINVCC -50 -25 0 25 50 75 100 125 150 Tj [] Fig.14 Input sequence Fig.13 Input sequence 0.9 2.0 0.8 1.8 0.7 1.6 Fig.15 Tj-Vo (Io=0mA) 3.0 2.5 0.6 ISTB [A] IIN [mA] Icc [mA] 2.0 1.4 1.5 1.0 0.5 1.2 0.4 0.5 1.0 -50 -25 0 25 50 75 100 125 150 0.0 -50 -25 0 25 Tj [] 75 100 125 150 INRCS [A] 20 15 10 5 25 50 25 75 100 125 20 10 19 9 18 8 17 7 16 6 15 14 100 125 150 4 3 12 2 11 1 0 -50 -25 0 25 50 75 100 125 150 Tj [] Tj [] Fig.19 Tj-IINSTB -50 -25 0 25 50 75 100 125 150 Tj [] Fig.20 Tj-NRSC 150 75 5 13 150 50 Fig.18 Tj-ICCSTB 10 0 0 0 Tj [] IEN [ A] 25 -25 -25 Fig.17 Tj-IIN 30 -50 -50 Tj [] Fig.16 Tj-ICC IINSTB [A] 50 Fig.21 Tj-IEN 135 125 130 Vo=2.5V RON [m] RON [m] 115 110 90 Vo=1.8V 105 Vo=1.5V Vo=1.2V 95 Vo=1.0V 70 85 50 75 -50 -25 0 25 50 75 100 125 150 Tj [] Fig.22 Tj-RON (Vcc=5V/Vo=1.2V) www.rohm.com (c) 2009 ROHM Co., Ltd. All rights reserved. 3 4 5 6 7 8 Tj [] Fig.23 Vcc- RON 7/20 2009.04 - Rev.B Technical Note BD3523HFN, BD35230HFN, BD35231HFN Block Diagram BD3523HFN VCC C1 VCC 1 UVLO2 VCC EN Reference Block 2 VIN UVLOLATCH VCC EN UVLO1 CL UVLO1 VREF2 Current Limit VIN 4 VIN C2 VCC VREF1 NRCS SCP/TSD LATCH NRCS0.3. VREF1x0.4 FB LATCH EN UVLO1 TSD CL UVLO1 UVLO2 TSD SCP VO VO 5 6 EN R2 CFB C3 7 FB R1 NRCS 3 CNRCS NRCS EN/UVLO 8 GND BD35230HFN/BD35231HFN VCC C1 VCC 1 UVLO2 VCC EN 2 Reference Block R2 VIN UVLOLATCH VCC EN UVLO1 CL UVLO1 VREF2 R1 Current Limit 4 VIN VIN C2 VCC VREF1 NRCS NRCS0.3. VREF1x0.4 FB TSD SCP/TSD LATCH LATCH EN UVLO1 CL UVLO1 UVLO2 TSD SCP 5 EN VO VO CFB 6 C3 VOS R2 7 R1 NRCS CNRCS 3 FB NRCS EN/UVLO 8 www.rohm.com (c) 2009 ROHM Co., Ltd. All rights reserved. 8/20 GND 2009.04 - Rev.B Technical Note BD3523HFN, BD35230HFN, BD35231HFN Pin Layout BD3523HFN BD35230HFN/BD35231HFN 6 6 Vcc 1 8 GND Vcc EN 2 7 FB EN 1 8 GND 2 7 FB FIN FIN NRCS 3 6 Vo NRCS 3 6 Vos VIN 4 5 Vo VIN 4 5 Vo Pin Function Table BD3523HFN BD35230HFN/BD35231HFN PIN No. 1 2 PIN name VCC EN 3 NRCS 4 5 6 7 8 - VIN VO VO FB GND FIN PIN Function Power Supply Pin Enable Input Pin In-rush Current Protection (NRCS) Capacitor Connection Pin Input Voltage Pin Output Voltage Pin Output Voltage Pin Reference Voltage Feedback Pin Ground Pin Connected to heatsink and GND www.rohm.com (c) 2009 ROHM Co., Ltd. All rights reserved. 9/20 PIN No. 1 2 PIN name VCC EN 3 NRCS 4 5 6 7 8 - VIN VO VOS FB GND FIN PIN Function Power Supply Pin Enable Input Pin In-rush Current Protection (NRCS) Capacitor Connection Pin Input Voltage Pin Output Voltage Pin Output Voltage Control Pin Reference Voltage Feedback Pin Ground Pin Connected to heatsink and GND 2009.04 - Rev.B Technical Note BD3523HFN, BD35230HFN, BD35231HFN Operation of Each Block AMP This is an error amp that compares the reference voltage (0.65V) with VO to drive the output Nch FET (Ron=150m). Frequency optimization helps to realize rapid transient response, and to support the use of ceramic capacitors on the output capacitors. AMP input voltage ranges from GND to 2.7V, while the AMP output ranges from GND to VCC. When EN is OFF, or when UVLO is active, output goes LOW and the output of the NchFET switches OFF. EN The EN block controls the regulator's ON/OFF state via the EN logic input pin. In the OFF position, circuit voltage is maintained at 0A, thus minimizing current consumption at standby. The FET is switched ON to enable discharge of the NRCS pin VO, thereby draining the excess charge and preventing the IC on the load side from malfunctioning. Since no electrical connection is required (e.g. between the VCC pin and the ESD prevention diode), module operation is independent of the input sequence. VCCUVLO To prevent malfunctions that can occur during a momentary decrease in VCC, the UVLO circuit switches the output OFF, and (like the EN block) discharges NRCS and VO. Once the UVLO threshold voltage (TYP3.80V) is reached, the power-on reset is triggered and output continues. VINUVLO When VD voltage exceeds the threshold voltage, VDUVLO becomes active. Once active, the status of output voltage remains ON even if VD voltage drops. (When VIN voltage drops, SCP engages and output switches OFF.) Unlike EN and VCC, it is effective at output startup. VDUVLO can be restored either by reconnecting the EN pin or VCC pin. CURRENT LIMIT When output is ON, the current limit function monitors the internal IC output current against the parameter value. When current exceeds this level, the current limit module lowers the output current to protect the load IC. When the overcurrent state is eliminated, output voltage is restored to the parameter value. However, when output voltage falls to or below the SCP startup voltage, the SCP function becomes active and the output switches OFF. NRCS (Non Rush Current on Start-up) The soft start function enabled by connecting an external capacitor between the NRCS pin and ground. Output ramp-up can be set for any period up to the time the NRCS pin reaches VFB (0.65V). During startup, the NRCS pin serves as a 20A (TYP) constant current source to charge the external capacitor. Output start time is calculated via the formula below. TNRCS (typ.) = CNRCSxVFB INRCS TSD (Thermal Shut down) The shutdown (TSD) circuit automatically is latched OFF when the chip temperature exceeds the threshold temperature after the programmed time period elapses, thus serving to protect the IC against "thermal runaway" and heat damage. Because the TSD circuit is intended to shut down the IC only in the presence of extreme heat, it is crucial that the Tj (max) parameter not be exceeded in the thermal design ,in order to avoid potential problems with the TSD. TTSD (typ.) = CSCPxVSCPTH 20uA VIN The VIN line acts as the major current supply line, and is connected to the output NchFET drain. Since no electrical connection (such as between the VCC pin and the ESD protection diode) is necessary, VIN operates independent of the input sequence. However, since an output NchFET body diode exists between VIN and VO, a VIN-VO electric (diode) connection is present. Note, therefore, that when output is switched ON or OFF, reverse current may flow to VIN from VO. SCP When output voltage (Vo) drops, the IC assumes that VO pin is shorted to GND and switches the output voltage OFF. After the GND short has been detected and the programmed delay time has elapsed, output is latched OFF. It is also effective during output startup. SCP can be cleared either by reconnecting the EN pin or VCC pin. Delay time is calculated via the formula below. TSCP (typ.) = CSCPxVSCPTH www.rohm.com (c) 2009 ROHM Co., Ltd. All rights reserved. ISCP 10/20 2009.04 - Rev.B Technical Note BD3523HFN, BD35230HFN, BD35231HFN Timing Chart EN ON/OFF VIN VCC EN 0.65V(typ) NRCS Startup Vo t VCC ON/OFF VIN UVLO Hysteresis VCC EN 0.65V(typ) NRCS Startup Vo t www.rohm.com (c) 2009 ROHM Co., Ltd. All rights reserved. 11/20 2009.04 - Rev.B Technical Note BD3523HFN, BD35230HFN, BD35231HFN Timing Chart VIN ON VINUVLO VIN VCC EN NRCS Vo SCP OFF VIN VCC EN NRCS Vo www.rohm.com (c) 2009 ROHM Co., Ltd. All rights reserved. SCP startup voltage 12/20 SCP delay time 2009.04 - Rev.B Technical Note BD3523HFN, BD35230HFN, BD35231HFN Evaluation Board BD3523HFN Evaluation Board Schematic GND_S VCC 1 VCC VCC 8 GND C1 SW1 R8 GND U1 GND 2 EN C12 R1 FB 7 BD3523HFN GND 3 R4 C11 C13 R2 GND 6 Vo NRCS Vo S VIN_S GND 4 VIN C4 GND C7 GND C3 GND Vo 5 C5 C2 GND GND GND C8 C6 GND GND R3 R5 C9 7568 R6 4 TP1 GND U2 TP2 321 VCC GND U3 GND GND GND 5 2 3 C14 BD3523HFN Evaluation Board List Component Rating Manufacturer U1 C1 C3 C5 C11 1F 10F 22F 0.01F ROHM MURATA KYOCERA KYOCERA MURATA R7 JPF1 GND JPF2 4 R9 Product Name Component Rating Manufacturer Product Name BD3523XHFN GRM188B11A105KD CM32X5R226M10A CM32X5R226M10A GRM188B11H103KD C13 R1 R2 R4 R8 1000pF 3.9k 3.3k 0 0 MURATA ROHM ROHM - GRM188B11H102KD MCR03EZPF3301 MCR03EAPF3901 Jumper Jumper BD3523HFN Evaluation Board Layout (2nd layer and 3rd layer are GND line.) Silk Screen www.rohm.com (c) 2009 ROHM Co., Ltd. All rights reserved. TOP Layer 13/20 Bottom Layer 2009.04 - Rev.B Technical Note BD3523HFN, BD35230HFN, BD35231HFN Evaluation Board BD35230HFN / BD35231HFN Evaluation Board Schematic GND_S VCC 8 1 VCC VCC GND C1 SW1 R8 2 EN C12 GND U1 GND GND GND 7 BD35230HFN/ C13 BD35231HFN 3 R4 C11 FB 6 Vos NRCS Vo_S VIN_S GND 4 VIN C7 C4 C3 5 Vo C5 C2 C6 C8 R3 R5 C9 GND GND GND GND GND GND GND GND GND VCC TP2 7568 U2 GND GND GND JPF2 5 2 TP1 4 R7 321 GND U3 R6 JPF1 GND 4 3 C14 R9 BD35230HFN / BD35231HFN Evaluation Board List Component Rating Manufacturer Product Name Component Rating Manufacturer Product Name U1 - ROHM BD3523XHFN C13 1000pF MURATA GRM188B11H102KD C1 1F MURATA GRM188B11A105KD R1 3.9k ROHM MCR03EZPF3301 C3 10F KYOCERA CM32X5R226M10A R2 3.3k ROHM MCR03EAPF3901 C5 22F KYOCERA CM32X5R226M10A R4 0 - Jumper BD35230HFN / BD35231HFN Evaluation Board Layout (2nd layer and 3rd layer are GND line.) Silk Screen www.rohm.com (c) 2009 ROHM Co., Ltd. All rights reserved. TOP Layer 14/20 Bottom Layer 2009.04 - Rev.B Technical Note BD3523HFN, BD35230HFN, BD35231HFN Recommended Circuit Example (BD3523HFN) Vcc 1 Vcc 2 EN 6 GND 8 GND C1 R1 FB 7 FB R4 EN R2 3 Vo NRCS 6 4 Component 3.3k /3.9k C3 22F C1/ C2 C4 C5 R4 1F/22F 0.01F Several k several 10k Vo VIN 5 C2 Recommended Value R1/R2 Vo C3 C4 VIN C5 Programming Notes and Precautions IC output voltage can be set with a configuration formula VFBx(R1+R2)/R7 using the values for the internal reference output voltage (VFB) and the output voltage resistors (R6, R7). Select resistance values that will avoid the impact of the FB bias current (100nA). The recommended total resistance value is 10k. To assure output voltage stability, please be certain the output capacitors are connected between Vo1, Vo2, Vo3 pin and GND. Output capacitors play a role in loop gain phase compensation and in mitigating output fluctuation during rapid changes in load level. Insufficient capacitance may cause oscillation, while high equivalent series reisistance (ESR) will exacerbate output voltage fluctuation under rapid load change conditions. While a 47F ceramic capacitor is recomended, actual stability is highly dependent on temperature and load conditions. Also, note that connecting different types of capacitors in series may result in insufficient total phase compensation, thus causing oscillation. In light of this information, please confirm operation across a variety of temperature and load conditions. Input capacitors reduce the output impedance of the voltage supply source connected to the input pin (VCC,). If the impedance of this power supply were to increase, input voltage (VCC) could become unstable, leading to oscillation or lowered ripple rejection function. While a low-ESR 1F capacitor with minimal susceptibility to temperature is recommended, stability is highly dependent on the input power supply characteristics and the substrate wiring pattern. In light of this information, please confirm operation across a variety of temperature and load conditions. The Non Rush Current on Startup (NRCS) function is built into the IC to prevent rush current from going through the load (VIN to VO) and impacting output capacitors at power supply start-up. Constant current comes from the NRCS pin when EN is HIGH or the UVLO function is deactivated. The temporary reference voltage is proportionate to time, due to the current charge of the NRCS pin capacitor, and output voltage start-up is proportionate to this reference voltage. Capacitors with low susceptibility to temperature are recommended, in order to assure a stable soft-start time. This component is employed when the C3 capacitor causes, or may cause, oscillation. It provides more precise internal phase correction. It is recommended that a resistance (several k to several 10k) be put in R4, in case negative voltage is applied in EN pin. www.rohm.com (c) 2009 ROHM Co., Ltd. All rights reserved. 15/20 2009.04 - Rev.B Technical Note BD3523HFN, BD35230HFN, BD35231HFN Recommended Circuit Example (BD35230HFN/BD35231HFN) Vcc 1 Vcc 2 EN 6 GND 8 GND C1 R4 FB 7 EN FB C5 3 Vo NRCS 6 C4 C3 4 VIN Vo Vo VIN 5 C2 Recommended Value Programming Notes and Precautions 22F To assure output voltage stability, please be certain the output capacitors are connected between Vo pin and GND. Output capacitors play a role in loop gain phase compensation and in mitigating output fluctuation during rapid changes in load level. Insufficient capacitance may cause oscillation, while high equivalent series reisistance (ESR) will exacerbate output voltage fluctuation under rapid load change conditions. While a 22F ceramic capacitor is recomended, actual stability is highly dependent on temperature and load conditions. Also, note that connecting different types of capacitors in series may result in insufficient total phase compensation, thus causing oscillation. In light of this information, please confirm operation across a variety of temperature and load conditions. 1F/10F Input capacitors reduce the output impedance of the voltage supply source connected to the (VCC, VIN) input pins. If the impedance of this power supply were to increase, input voltage (VCC, VIN) could become unstable, leading to oscillation or lowered ripple rejection function. While a low-ESR 1F/10F capacitor with minimal susceptibility to temperature is recommended, stability is highly dependent on the input power supply characteristics and the substrate wiring pattern. In light of this information, please confirm operation across a variety of temperature and load conditions. C4 0.01F The Non Rush Current on Startup (NRCS) function is built into the IC to prevent rush current from going through the load (VIN to VO) and impacting output capacitors at power supply start-up. Constant current comes from the NRCS pin when EN is HIGH or the UVLO function is deactivated. The temporary reference voltage is proportionate to time, due to the current charge of the NRCS pin capacitor, and output voltage start-up is proportionate to this reference voltage. Capacitors with low susceptibility to temperature are recommended, in order to assure a stable soft-start time. C5 1000pF This component is employed when the C16 capacitor causes, or may cause, oscillation. It provides more precise internal phase correction. Component C3 C1/C2 www.rohm.com (c) 2009 ROHM Co., Ltd. All rights reserved. 16/20 2009.04 - Rev.B Technical Note BD3523HFN, BD35230HFN, BD35231HFN Input-Output Equivalent Circuit Diagram (BD3523HFN) VCC VCC 1k EN VIN 1k NRCS 1k 1k VIN 210k 1k 1k 400k VIN 1k VIN VIN 90k VIN VCC VCC 10k Vo 50k 1k FB Vo 1k Vo 1k Vo Vo Vo Operation Notes 1. Absolute maximum ratings An excess in the absolute maximum ratings, such as supply voltage, temperature range of operating conditions, etc., can break down the devices, thus making impossible to identify breaking mode, such as a short circuit or an open circuit. If any over rated values will expect to exceed the absolute maximum ratings, consider adding circuit protection devices, such as fuses. 2. Connecting the power supply connector backward Connecting of the power supply in reverse polarity can damage IC. Take precautions when connecting the power supply lines. An external direction diode can be added. 3. Power supply lines Design PCB layout pattern to provide low impedance GND and supply lines. To obtain a low noise ground and supply line, separate the ground section and supply lines of the digital and analog blocks. Furthermore, for all power supply terminals to ICs, connect a capacitor between the power supply and the GND terminal. When applying electrolytic capacitors in the circuit, not that capacitance characteristic values are reduced at low temperatures. 4. GND voltage The potential of GND pin must be minimum potential in all operating conditions. 5. Thermal design Use a thermal design that allows for a sufficient margin in light of the power dissipation (Pd) in actual operating conditions. 6. Inter-pin shorts and mounting errors Use caution when positioning the IC for mounting on printed circuit boards. The IC may be damaged if there is any connection error or if pins are shorted together. 7. Actions in strong electromagnetic field Use caution when using the IC in the presence of a strong electromagnetic field as doing so may cause the IC to malfunction. www.rohm.com (c) 2009 ROHM Co., Ltd. All rights reserved. 17/20 2009.04 - Rev.B Technical Note BD3523HFN, BD35230HFN, BD35231HFN 8. ASO When using the IC, set the output transistor so that it does not exceed absolute maximum ratings or ASO. 9. Thermal shutdown circuit The IC incorporates a built-in thermal shutdown circuit (TSD circuit). The thermal shutdown circuit (TSD circuit) is designed only to shut the IC off to prevent thermal runaway. It is not designed to protect the IC or guarantee its operation. Do not continue to use the IC after operating this circuit or use the IC in an environment where the operation of this circuit is assumed. BD3523HFN/BD35230HFN/BD35231HFN TSD on temperature [C] (typ.) 175 10. Testing on application boards When testing the IC on an application board, connecting a capacitor to a pin with low impedance subjects the IC to stress. Always discharge capacitors after each process or step. Always turn the IC's power supply off before connecting it to or removing it from a jig or fixture during the inspection process. Ground the IC during assembly steps as an antistatic measure. Use similar precaution when transporting or storing the IC. 11. Regarding input pin of the IC This monolithic IC contains P+ isolation and P substrate layers between adjacent elements in order to keep them isolated. P-N junctions are formed at the intersection of these P layers with the N layers of other elements, creating a parasitic diode or transistor. For example, the relation between each potential is as follows: When GND > Pin A and GND > Pin B, the P-N junction operates as a parasitic diode. When GND > Pin B, the P-N junction operates as a parasitic transistor. Parasitic diodes can occur inevitable in the structure of the IC. The operation of parasitic diodes can result in mutual interference among circuits, operational faults, or physical damage. Accordingly, methods by which parasitic diodes operate, such as applying a voltage that is lower than the GND (P substrate) voltage to an input pin, should not be used. Resistor Transistor (NPN) Pin A Pin B C Pin B B E Pin A N P + N P P + N Parasitic element N P+ P substrate Parasitic element GND B N P P C + N E Parasitic element P substrate Parasitic element GND GND GND Other adjacent elements Example of IC structure 12. Ground Wiring Pattern. When using both small signal and large current GND patterns, it is recommended to isolate the two ground patterns, placing a single ground point at the ground potential of application so that the pattern wiring resistance and voltage variations caused by large currents do not cause variations in the small signal ground voltage. Be careful not to change the GND wiring pattern of any external components, either. www.rohm.com (c) 2009 ROHM Co., Ltd. All rights reserved. 18/20 2009.04 - Rev.B Technical Note BD3523HFN, BD35230HFN, BD35231HFN Heat Loss Thermal design should allow operation within the following conditions. Note that the temperatures listed are the allowed temperature limits, and thermal design should allow sufficient margin from the limits. 1. Ambient temperature Ta can be no higher than 100. 2. Chip junction temperature (Tj) can be no higher than 150. Chip junction temperature can be determined as follows: Calculation based on ambient temperature (Ta) Tj=Ta+j-axW Reference values j-a: HSON8 198.4/W 1-layer substrate (copper foil area : below 0.2%) 92.4/W 1-layer substrate (copper foil area : 7%) 71.4/W 2-layer substrate (copper foil area : 65%) 3 Substrate size: 70x70x1.6mm (substrate with thermal via) It is recommended to layout the VIA for heat radiation in the GND pattern of reverse (of IC) when there is the GND pattern in the inner layer (in using multiplayer substrate). This package is so small (size: 2.9mmx3.0mm) that it is not available to layout the VIA in the bottom of IC. Spreading the pattern and being increased the number of VIA like the figure below enable to get the superior heat radiation characteristic. (This figure is the image. It is recommended that the VIA size and the number is designed suitable for the actual situation.). Most of the heat loss that occurs in the BD3523XHFN is generated from the output Nch FET. Power loss is determined by the total VIN-Vo voltage and output current. Be sure to confirm the system input and output voltage and the output current conditions in relation to the heat dissipation characteristics of the VIN and Vo in the design. Bearing in mind that heat dissipation may vary substantially depending on the substrate employed (due to the power package incorporated in the BD3523XHFN) make certain to factor conditions such as substrate size into the thermal design. Power consumption (W) = Input voltage (VIN)- Output voltage (Vo) xIo(Ave) Example) Where VIN=1.7V, Vo=1.2V, Io(Ave) = 2A, Power consumption (W) = 1.7(V)-1.2(V) x2.0(A) = 1.0(W) Heat Dissipation Characteristics HSON8 Power Dissipation [Pd] [W] 2.0 (3) 1.75W (1) 1 layer substrate (substrate surface copper foil area: below 0.2%) j-a=198.4/W (2) 2 layer substrate (substrate surface copper foil area:7%) j-a=92.4/W (3) 2 layer substrate (substrate surface copper foil area:65%) j-a=71.4/W 1.5 (2) 1.35W 1.0 (1) 0.63W 0.5 0 0 25 50 75 100 Ambient Temperature [Ta] www.rohm.com (c) 2009 ROHM Co., Ltd. All rights reserved. 125 150 [] 19/20 2009.04 - Rev.B Technical Note BD3523HFN, BD35230HFN, BD35231HFN Ordering part number B D 3 Part No. 5 2 3 H Part No. 3523 35230 35231 F N - Package HFN : HSON8 T R Packaging and forming specification TR: Embossed tape and reel HSON8 (0.05) (0.3) (0.2) 1234 5678 (0.45) (0.2) (1.8) 8 765 2.8 0.1 3.0 0.2 0.475 (2.2) (0.15) 2.90.1 (MAX 3.1 include BURR) 4321 Tape Embossed carrier tape Quantity 3000pcs Direction of feed +0.1 0.13 -0.05 TR The direction is the 1pin of product is at the upper right when you hold ( reel on the left hand and you pull out the tape on the right hand 1pin 1PIN MARK S +0.03 0.02 -0.02 0.6MAX ) 0.1 S 0.65 0.320.1 0.08 Direction of feed M (Unit : mm) www.rohm.com (c) 2009 ROHM Co., Ltd. All rights reserved. Reel 20/20 Order quantity needs to be multiple of the minimum quantity. 2009.04 - Rev.B Notice Notes No copying or reproduction of this document, in part or in whole, is permitted without the consent of ROHM Co.,Ltd. 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If a Product is intended to be used for any such special purpose, please contact a ROHM sales representative before purchasing. If you intend to export or ship overseas any Product or technology specified herein that may be controlled under the Foreign Exchange and the Foreign Trade Law, you will be required to obtain a license or permit under the Law. Thank you for your accessing to ROHM product informations. More detail product informations and catalogs are available, please contact us. ROHM Customer Support System http://www.rohm.com/contact/ www.rohm.com (c) 2009 ROHM Co., Ltd. All rights reserved. R0039A