L6997STR

L6997S STEP DOWN CONTROLLER FOR LOW VOLTAGE OPERATIONS 1 ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ 2 Figure 1. Package Features FROM 3V TO 5.5V VCC RANGE MINIMUM OUTPUT VOLTAGE AS LOW AS 0.6V 1V TO 35V INPUT VOLTAGE RANGE CONSTANT ON TIME TOPOLOGY VERY FAST LOAD TRANSIENTS 0.6V, ±1% VREF SELECTABLE SINKING MODE LOSSLESS CURRENT LIMIT, AVAILABLE ALSO IN SINKING MODE REMOTE SENSING OVP,UVP LATCHED PROTECTIONS 600µA TYP QUIESCENT CURRENT POWER GOOD AND OVP SIGNALS PULSE SKIPPING AT LIGTH LOADS 94% EFFICIENCY FROM 3.3V TO 2.5V TSSOP20 Table 1. Order Codes 3 Applications NETWORKING ■ DC/DC MODULES ■ DISTRIBUTED POWER ■ MOBILE APPLICATIONS ■ CHIP SET, CPU, DSP AND MEMORIES SUPPLY Figure 2. Minimum Component Count Application ■ Part Number Package L6997S TSSOP20 L6997STR Tape & Reel Description The device is a high efficient solution for networking dc/dc modules and mobile applications compatible with 3.3V bus and 5V bus. It's able to regulate an output voltage as low as 0.6V. The constant on time topology assures fast load transient response. The embedded voltage feed-forward provides nearly constant switching frequency operation in spite of a wide input voltage range. An integrator can be introduced in the control loop to reduce the static output voltage error. The remote sensing improves the static and dynamic regulation, recovering the wires voltage drop. Pulse skipping technique reduces power consumption at light loads. Drivers current capability allows output currents in excess of 20A. 3.3V Rin2 Rin1 VCC VDR Cin OSC Dboot BOOT HGATE HS Cboot L 0.6V PHASE PGOOD Ro1 OVP LGATE ILIM L6997SPGND LS DS Cout Ro2 GND GNDSENSE Rilim SS Css VSENSE INT VFB SHDN Vref Cvref June 2004 REV. 1 1/30 L6997S Table 2. Absolute Maximum Ratings Symbol Parameter VCC VDR VPHASE BOOT, HGATE and PHASE PINS Value Unit VCC to GND -0.3 to 6 V VDR to GND -0.3 to 6 V HGATE and BOOT, to PHASE -0.3 to 6 V HGATE and BOOT, to PGND -0.3 to 42 V PHASE -0.3-to 36 V LGATE to PGND -0.3 to VDR+0.3 V ILIM, VFB, VSENSE, NOSKIP, SHDN, PGOOD, OVP, VREF, INT, GNDSENSE to GND -0.3 to VCC+0.3 V ±750 V Maximum Withstanding Voltage Range Test Condition:CDF-AEC-Q100-002 “Human Body Model” Accepatance Criteria: “Normal Performance” OTHER PINS Ptot Power dissipation at Tamb = 25°C Tstg Storage temperature range ±2000 V 1 W -40 to 150 °C Value Unit 125 °C/W -40 to 125 °C Table 3. Thermal Data Symbol Rth j-amb Tj Parameter Thermal Resistance Junction to Ambient Junction operating temperature range Figure 3. Pin Connection (Top View) NOSKIP 1 20 BOOT GNDSENSE 2 19 HGATE INT 3 18 PHASE VSENSE 4 17 VDR VCC 5 16 LGATE GND 6 15 PGND VREF 7 14 PGOOD VFB 8 13 OVP OSC 9 12 SHDN 11 ILIM SS 10 TSSOP20 Table 4. Pin Function N° Name 1 NOSKIP 2 GNDSENSE 3 INT 4 VSENSE 2/30 Description Connect to VCC to force continuous conduction mode and sink mode. Remote ground sensing pin Integrator output. Short this pin to VFB pin and connect it via a capacitor to VOUT to insert the integrator in the control loop. If the integrator is not used, short this pin to VREF. This pin must be connected to the remote output voltage to detect overvoltage and undervoltage conditions and to provide integrator feedback input. L6997S Table 4. Pin Function (continued) N° Name 5 VCC IC Supply Voltage. Description 6 GND Signal ground 7 VREF 0.6V voltage reference. Connect a ceramic capacitor (max. 10nF) between this pin and ground. This pin is capable to source or sink up to 250uA 8 VFB PWM comparator feedback input. Short this pin to INT pin to enable the integrator function, or to VSENSE to disable the integrator function. 9 OSC Connect this pin to the input voltage through a voltage divider in order to provide the feedforward function don’t leave floating. 10 SS Soft Start pin. A 5µA constant current charges an external capacitor. Itsvalue sets the softstart time don’t leave floating. 11 ILIM 12 SHDN Shutdown. When connected to GND the device and the drivers are OFF. It cannot be left floating. 13 OVP Open drain output. During the over voltage condition it is pulled up by an external resistor. 14 PGOOD An external resistor connected between this pin and GND sets the current limit threshold don’t leave floating.. Open drain output. It is pulled down when the output voltage is not within the specified thresholds. Otherwise is pulled up by external resistor. If not used it can be left floating. 15 PGND Low Side driver ground. 16 LGATE Low Side driver output. 17 VDR Low Side driver supply. 18 PHASE 19 HGATE High side driver output. 20 BOOT Bootstrap capacitor pin. High Side driver is supplied through this pin. Return path of the High Side driver. Table 5. Electrical Characteristics (VCC = VDR = 3.3V; Tamb = 0°C to 85°C unless otherwise specified) Symbol Parameter Test Condition Min. Typ. Max. Unit SUPPLY SECTION Vin Input voltage range Vout=Vref Fsw=110Khz Iout=1A 1 35 V 3 5.5 V Turn-onvoltage 2.86 2.97 V Turn-off voltage 2.75 2.9 V VCC, VDR VCC Hysteresis 90 mV IqVDR Drivers Quiescent Current VFB > VREF 7 20 µA IqVcc Device Quiescent current VFB > VREF 400 600 µA SHUTDOWN SECTION SHDN Device On 1.2 V Device Off ISHVDR Drivers shutdown current SHDN to GND ISHVCC Devices shutdown current SHDN to GND 0.6 V 5 µA 1 15 µA 6 µA 400 500 mV SOFT START SECTION ISS ∆VSS Soft Start current Active Soft start and voltage VSS = 0.4V 4 300 3/30 L6997S Table 5. Electrical Characteristics (continued) (VCC = VDR = 3.3V; Tamb = 0°C to 85°C unless otherwise specified) Symbol Parameter Test Condition Min. Typ. Max. Unit 4.6 5 5.4 µA 2 mV CURRENT LIMIT AND ZERO CURRENT COMPARATOR ILIM KILIM Input bias current RILIM = 2KΩ to 200KΩ Zero Crossing Comparator offset Phase-gnd -2 Current limit factor 1.6 1.8 2 µA VREF=VSENSE OSC=125mV 720 800 880 ns VREF=VSENSE OSC=250mV 370 420 470 ns VREF=VSENSE OSC=500mV 200 230 260 ns VREF=VSENSE OSC=1000mV 90 115 140 ns 600 ns ON TIME Ton On time duration OFF TIME TOFFMIN Minimum off time KOSC/TOFFMIN OSC=250mV 0.20 0µA < IREF < 100µA 0.594 0.40 VOLTAGE REFERENCE VREF Voltage Accuracy 0.6 0.606 V +2 mV PWM COMPARATOR Input voltage offset IFB -2 Input Bias Current 20 nA INTEGRATOR Over Voltage Clamp VSENSE = VCC 0.62 0.75 0.88 V Under Voltage Clamp VSENSE = GND 0.45 0.55 0.65 V -4 mV -4 Integrator Input Offset Voltage VSENSE-VREF IVSENSE Input Bias Current 20 nA GATE DRIVERS High side rise time High side fall time Low side rise time Low side fall time VDR=3.3V; C=7nF HGATE - PHASE from 1 to 3V 50 90 ns 50 100 ns VDR=3.3V; C=14nF LGATE from 1 to 3V 50 90 ns 50 90 ns 121 124 % PGOOD UVP/OVP PROTECTIONS OVP UVP VPGOOD 4/30 with respect to VREF 118 67 70 73 % Upper threshold (VSENSE-VREF) VSENSE rising 110 112 116 % Lower threshold (VSENSE-VREF) VSENSE falling 85 88 91 % 0.2 0.4 V Over voltage threshold Under voltage threshold ISink=2mA V IN 5 uA 0.6V VREF OSC SENSEGND Gm + + - VREF soft-start control IC enable power management 1.236V bandgap HS control pwm comparator 1.416 - + + Reference chain VREF 0.05 + positive current limit comparator PHASE VREF VSENSE INT FB ILIM SS NOSKIP OVP R one-shot Ton Ton min one-shot Toff min delay S 1.12 VREF - VSENSE 0.6 VREF 0.925 VREF VSENSE VSENSE 1.075 VREF LS control PHASE S R VCC Q GND zero-cross comparator - + no-skip mode Ton= Kosc V(VSENSE)/V(OSC) - + - + pgood comparators + - undervoltage comparator VSENSE + overvoltage comparator OSC PGOOD VSENSE no-skip mode R S - + - + Q S R one-shot Ton Q level shifter OSC LS driver HS driver 0.05 ILIM negative current limit comparator Ton= Kosc V(VSENSE)/V(OSC) PHASE V(PHASE) Output voltage Figure 29. Eff. vs Output Current sink mode Figure 31. Normal functionality in SINK mode.. 100 Efficiency (%) 95 90 85 Vin = 1.8V 80 Vout=0.9V Vcc=5V Fsw=200KHz 75 70 65 Vin=12V Vin = 12V 60 0 1 2 3 4 5 6 7 Output current (A) Ch1-> Inductor current Ch2-> Phase Node Ch3-> Output voltage 26/30 L6997S Figure 32. Normal functionality in PWM mode. Ch1-> Inductor current Ch2-> Phase Node Ch3-> Output voltage Figure 33. Normal functionality in PFM mode. Ch1-> Inductor current Ch2-> Phase Node Ch3-> Output voltage Figure 34. Start up waveform with 0A load. Ch1-> Inductor current Ch2-> Soft start Voltage Ch3-> Output voltage Figure 35. Start up waveform with 5A load.. Ch1-> Inductor current Ch2-> Soft start Voltage Ch3-> Output voltage 27/30 L6997S Figure 36. TSSOP20 Mechanical Data & Package Dimensions mm inch DIM. MIN. TYP. A MAX. MIN. TYP. 1.20 A1 0.050 A2 0.800 b MAX. 0.047 0.150 0.002 1.050 0.031 0.190 0.300 0.007 0.012 c 0.090 0.200 0.004 0.008 D (1) 6.400 6.500 6.600 0.252 0.256 0.260 E 6.200 6.400 6.600 0.244 0.252 0.260 E1 (1) 4.300 4.400 4.500 0.170 0.173 0.177 e L L1 k aaa 1.000 0.650 0.450 0.600 OUTLINE AND MECHANICAL DATA 0.006 0.039 0.041 0.026 0.750 0.018 1.000 0.024 0.030 0.039 0˚ (min.) 8˚ (max.) 0.100 0.004 Note: 1. D and E1 does not include mold flash or protrusions. Mold flash or potrusions shall not exceed 0.15mm (.006inch) per side. TSSOP20 Thin Shrink Small Outline Package 0087225 (Jedec MO-153-AC) 28/30 L6997S Table 15. Revision History Date Revision June 2004 1 Description of Changes First Issue. 29/30 L6997S Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics. The ST logo is a registered trademark of STMicroelectronics. All other names are the property of their respective owners © 2004 STMicroelectronics - All rights reserved STMicroelectronics GROUP OF COMPANIES Australia - Belgium - Brazil - Canada - China - Czech Republic - Finland - France - Germany - Hong Kong - India - Israel - Italy - Japan Malaysia - Malta - Morocco - Singapore - Spain - Sweden - Switzerland - United Kingdom - United States www.st.com 30/30