BlueChips Technology BCT1583S 3A Step Down DC/DC Converter A premier Mixed Signal Product Company GENERAL DESCRIPTION The BCT1583S is a step down monolithic regulator with a built in internal power MOSFET, capable of driving up to 3A continuous output current with excellent line and load regulation. The output voltage can be set from 1.22 to 18V. Requiring a minimum number of external components, it offers simple to use, but high efficiency and advanced protection features including pulse-by-pulse current limiting and thermal shutdown. Adjustable soft-start reduces the stress on the input source at turn-on and the regulator draws only 20uA in shutdown mode. BCT1583S is available in a Pb-Free SOIC8 with Exposed Pad package. FEATURES APPLICATIONS • • • • • • • • • • • • • Wide Vin Range: 4.5 to 20V 3A Output Current High Efficiency up to 95% Output Adjustable from 1.22 to 18V 385KHz Fixed Frequency internal oscillator 20uA Shutdown Mode Pulse-to-Pulse Over Current Protection Thermal Shutdown • Automatic Soft Start • Compact SOIC8 with Exposed Pad Simple High Efficiency Step-down Consumer: TV, STB, DVD, VCR Car Audio/TV/Navigation Battery Charger Pre-Regulator for Linear Regulators Typical Application INPUT OUTPUT BCT1583S .2/2007 Ver 1.1 Page 1 BlueChips Technology BCT1583S 3A Step Down DC/DC Converter A premier Mixed Signal Product Company Pin Assignment Pin Descriptions Pin # Pin Name 1 BS High Side Gate Drive Boost Input 2 IN Power Input 3 SW 4 GND 5 FB 6 COMP 7 EN Enable Input (H: Step-down Operation, L: All circuits deactivated) 8 SS Soft Start Control Input BCT1583S .2/2007 Description Power Switching Output Ground Feedback Input Compensation Node Ver 1.1 Page 2 BlueChips Technology BCT1583S 3A Step Down DC/DC Converter A premier Mixed Signal Product Company Block Diagram Absolute Maximum Specifications Rating Symbol Value Unit Supply Voltage Range VIN -0.3 to 28 Volts Switch Voltage Range VSW -1 to VIN+0.3 Volts Boost Voltage Range VBS Vsw-0,3 to Vsw+6 Volts -0.3 to 6 Volts All Other Pins Storage Temperature Range TSTR -65 to 150 0 Maximum Operating Junction Temp TJ 150 0 BCT1583S .2/2007 C C Ver 1.1 Page 3 BlueChips Technology BCT1583S 3A Step Down DC/DC Converter A premier Mixed Signal Product Company Recommended Operating Ratings Rating Symbol Value Unit Supply Voltage Range VIN -4.5 to 20 Volts Ambient Operating Temperature TOP -40 to 85 0 C Electrical Specifications 0 All electrical specifications are specified at TAMBIENT = 25 C, VIN = 12V, unless otherwise specified. Symbol Parameter Test Conditions Shutdown Supply Current VEN=0V 20 µA Supply Current VEN=4V 1.0 mA Feedback Voltage VFB (Simulated over all corners and temperature) AEA Error Amplifier Voltage Gain GEA Error Amplifier Transconductance RDS(ON)1 RDS(ON)2 4.5V VIN 20V Min 1.150 Typ 1.222 Max 1.290 Unit V 1000 V/V 800 µA/V High Side Switch-On Resistance 100 m Low Side Switch-On Resistance 10 High Side Switch Leakage Current ∆ICOMP = ±10µA VEN=0V, VSW=0V 0 10 µA Upper Switch Current Limit 5.5 A GCS Current Sense to COMP Transconductance 3.8 A/V FOSC1 Oscillation Frequency 385 KHz BCT1583S .2/2007 Ver 1.1 Page 4 BlueChips Technology BCT1583S 3A Step Down DC/DC Converter A premier Mixed Signal Product Company FOSC2 Short Circuit Oscillation Frequency VFB=0V 40 KHz DMAX Maximum Duty Cycle VFB=1.0V 90 % DMIN Minimum Duty Cycle VFB=1.5V EN Threshold Voltage % 3.1 V EN Pull-up Current VEN=0V 1.9 µA Under-Voltage Lockout Threshold Rising VIN 3.4 V 600 mV 10 mS Under-Voltage Lockout Threshold Hysteresis Soft Start Period Thermal Shutdown BCT1583S .2/2007 0 CSS=0.1µF 160 0 C Ver 1.1 Page 5 BlueChips Technology BCT1583S 3A Step Down DC/DC Converter A premier Mixed Signal Product Company Performance Characteristics Soft Start VIN/VOUT = 12V/5V at Load Current 2A VIN/VOUT = 12V/5V with a 1uF cap Load Transient Waveform Turn Off Waveform VIN/VOUT = 12V/5V, 1A-2A Step VIN/VOUT = 12V/5V at Load Current 2A Efficiency at VIN/VOUT = 5.0V/1.8V Efficiency at VIN/VOUT = 10V/5.0V 100% 95% 90% 85% 80% 75% 70% 65% 60% 55% 50% E fficiency Efficiency Switching Waveforms ( VOUT & VSW) 0 0.5 1 1.5 Load Current (A) BCT1583S .2/2007 2 2.5 3 100% 95% 90% 85% 80% 75% 70% 65% 60% 55% 50% 0 0.5 1 1.5 2 Load Current (A) Ver 1.1 Page 6 BlueChips Technology BCT1583S 3A Step Down DC/DC Converter A premier Mixed Signal Product Company Typical Application Circuits U 2 -B EN C8 100 nF R1 10 k U1 C5 1 uF U 2 -D VIN C2 470 uF C4 100 nF BS SS IN EN COMP SW C1 10 nF U 2 -C U 2 -A GND C9 10 nF FB R4 15 k C 10 180 pF R3 15 k R5 6 .8 k U 3 -A L1 22 uH J2 D1 30 BQ 040 U 3 -C U 3 -B C 12 470 uF VOUT R6 C7 100 nF R7 R8 R9 R 10 R 11 U 3 -D *R6 - R11 = OPEN GND Figure 1: VIN = 5V, VOUT = 1.8V, IOUT = 0A~3A U 2 -B EN R1 80 .6 k U 2 -D R2 51 k C2 100 nF VIN C3 470 uF C4 100 nF C1 10 nF U1 BS SS IN EN SW GND U 2 -C U 2 -A COMP C9 10 nF FB R4 15 k C 10 100 pF R3 10 k R5 47 k U 3 -A L1 22 uH D1 30 BQ040 U 3 -C U 3 -B J2 C 12 470 uF C7 10 nF VOUT R6 GND R7 R8 R9 R 10 R 11 U 3 -D *R6 - R11 = OPEN Figure 2: VIN = 12V, VOUT = 5.0V, IOUT = 0A~3A BCT1583S .2/2007 Ver 1.1 Page 7 BlueChips Technology BCT1583S 3A Step Down DC/DC Converter A premier Mixed Signal Product Company Configuration Table VOUT R5 R3 C9 L1 1.8 V 2.5 V 3.3 V 5V 12 V 7.15 kΩ 15.4 kΩ 26.1 kΩ 46.4 kΩ 133 kΩ 3 kΩ 3.9 kΩ 5.6 kΩ 7.5 kΩ 10 kΩ 4.7 nF 5.6 nF 8.2 nF 10 nF 3.3 nF 4.7 µH 4.7 – 6.8 µH 6.8 – 10 µH 10 – 15 µH 15 – 22 µH Design Note 1. The voltage divider network formed by R4 and R5 sets the output voltage regulation point. It is calculated by the equation below: R5 R4 ⋅ VOUT − VREF Where: VREF = 1.22 V VREF From this equation the closest standard (E48) resistance values were chosen. VOUT can be further trimmed by adding a resistor across R5. Metal film resistors with 1% or less tolerance are recommended. 2. The EN pin provides an enabling feature and has the following turn-on/off characteristic: ON Threshold OFF Threshold = 3.1 V = 0.7 V To avoid intermittent turn-on/off, an Under Voltage Lock Out (UVLO) function is implemented by R1 & R2. VINuvlo is the selected turn-on threshold of the device. Use this formula: VIN uvlo BCT1583S .2/2007 1+ R1 R2 ⋅ VEN Where: VEN = 3.1 V Ver 1.1 Page 8 BlueChips Technology A premier Mixed Signal Product Company BCT1583S 3A Step Down DC/DC Converter Package Information: SO8 (Exposed Pad) SYMBOL A A1 A2 b c D D1 E E1 E2 e L BCT1583S .2/2007 MIN (Millimeter) MAX (Millimeter) 1.350 1.750 0.050 0.150 1.350 1.550 0.330 0.510 0.170 0.250 4.700 5.100 3.202 3.402 3.800 4.000 5.840 6.240 2.313 2.513 1.270 (BSC) 0.400 1.270 0o 8o Ver 1.1 Page 9 BlueChips Technology BCT1583S 3A Step Down DC/DC Converter A premier Mixed Signal Product Company Marking Notation 1583S XXXXX O IC Part Number Date Code: yyww Sales Offices Malaysia Hong Kong BCT Technology Bhd (HQ) BlueChips Technology Pte Ltd ) * 3 & $*&++ &, '- . % 01 2 / " / !" #$ ' (#$ %&&$% %% %&&$% % #% 44 $ &$% ' (#% 44 $%&& Singapore BlueChips Technology Pte Ltd 5 *+%, +&, 4 3 2 6 " 7 . " $ &&4 #$ $%& $& % ' (#$ $%&$ &4% All Rights Reserved. Specifications are subject to changes without notification. @ Copyright 2005 BlueChips Technology, Silicon Solutions Division www.bluechipstech.com BCT1583S .2/2007 Ver 1.1 Page 10