L6997DTR

L6997 STEP DOWN CONTROLLER FOR LOW VOLTAGE OPERATIONS FEATURES s FROM 3V TO 5.5V VCC RANGE. s MINIMUM OUTPUT VOLTAGE AS LOW AS 0.6V. s 1V TO 28V INPUT VOLTAGE RANGE. s CONSTANT ON TIME TOPOLOGY ALLOWS. OPERATION WITH VERYLOW AND HIGH DUTY CYCLES. s VERY FAST LOAD TRANSIENTS. s 0.6V, ±1% VREF. s SELECTABLE SINKING MODE. s LOSSLESS CURRENT LIMIT, AVAILABLE ALSO IN SINKING MODE s REMOTE SENSING. s OVP,UVP LATCHED PROTECTIONS. s 600 µA TYP QUIESCENT CURRENT. s POWER GOOD AND OVP SIGNALS. s PULSE SKIPPING AT LIGTH LOADS. s 94% EFFICIENCY FROM 3.3V TO 2.5V. APPLICATIONS s NETWORKING. s DC/DC MODULES. s DISTRIBUTED POWER. s MOBILE APPLICATIONS. s CHIP SET, CPU, DSP AND MEMORIES SUPPLY. MINIMUM COMPONENT COUNT APPLICATION 3.3V Rin2 Rin1 TSSOP20 ORDERING NUMBERS: L6997D L6997DTR DESCRIPTION The device is a high efficient solution for networking dc/dc modules and mobile application 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. 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. Cin VCC VDR OSC BOOT HGATE HS Cboot L PHASE PGOOD OVP LGATE LS DS Ro2 Ro1 Cout Dboot 0.6V L6997 ILIM Rilim PGND GND GNDSENSE SS Css VSENSE INT VFB SHDN Vref Cvref April 2003 1/23 L6997 ABSOLUTE MAXIMUM RATINGS Symbol VCC VDR VCC to GND VDR to GND HGATE and BOOT, to PHASE HGATE and BOOT, to PGND VPHASE PHASE LGATE to PGND ILIM, VFB, VSENSE, NOSKIP, SHDN, PGOOD, OVP, VREF, INT, GNDSENSE to GND Ptot Tstg Power dissipation at Tamb = 25°C Storage temperature range Parameter Value -0.3 to 6 -0.3 to 6 -0.3 to 6 -0.3 to 36 -0.3-to 30 -0.3 to VDR+0.3 -0.3 to VCC+0.3 1 -40 to 150 Unit V V V V V V V W °C THERMAL DATA Symbol Rth j-amb Tj Parameter Thermal Resistance Junction to Ambient Junction operating temperature range Value 125 -40 to 125 Unit °C/W °C PIN CONNECTION (Top View) NOSKIP GNDSENSE INT VSENSE VCC GND VREF VFB OSC SS 1 2 3 4 5 6 7 8 9 10 TSSOP20 20 19 18 17 16 15 14 13 12 11 BOOT HGATE PHASE VDR LGATE PGND PGOOD OVP SHDN ILIM PIN FUNCTION N° 1 2 3 4 5 6 7 Name NOSKIP GNDSE NSE INT VSENS E VCC GND VREF 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. IC Supply Voltage. Signal ground 0.6V voltage reference. Connect max. a 10nF ceramic capacitor between this pin and ground. This pin is capable to source or sink up to 250uA Description Connect to VCC to force continuous conduction mode and sink mode. 2/23 L6997 PIN FUNCTION (continued) N° 8 9 10 11 12 13 14 15 16 17 18 19 20 Name VFB OSC SS ILIM SHDN OVP PGOOD PGND LGATE VDR PHASE HGATE BOOT Description PWM comparator feedback input. Short this pin to INT pin when using the integrator function, or to VSENSE pin without integrator. Connect this pin to the input voltage through a voltage divider in order to provide the feedforward function. It cannot be left floating. Soft start pin. A 5µA constant current charges an external capacitor which value sets the softstart time. An external resistor connected between this pin and GND sets the current limit threshold. Shutdown. When connected to GND the device and the drivers are OFF. It cannot be left floating. Open drain output. During the over voltage condition it is pulled up by an external resistor. Open drain output. During the soft start and in case of output voltage fault it is low. It is pulled up by external resistor. Low Side driver ground. Low Side driver output. Low Side driver supply. Return path of the High Side driver. High side MOSFETS driver output. Bootstrap capacitor pin. High Side driver is supplied through this pin. ELECTRICAL CHARACTERISTICS (VCC = VDR = 3.3V; Tamb = 0°C to 85°C unless otherwise specified) Symbol SUPPLY SECTION Vin VCC, VDR VCC Turn-onvoltage Turn-off voltage Hysteresis IqVDR IqVcc Quiescent Current Drivers Device Quiescent current VFB > VREF VFB > VREF Input voltage range Vout=Vref Fsw=110Khz Iout=1A 1 3 2.86 2.75 90 7 400 20 600 28 5.5 2.97 2.9 V V V V mV µA µA V 0.6 SHDN to GND SHDN to GND 1 5 15 V µA µA µA mV µA mV µA Parameter Test Condition Min. Typ. Max. Unit SHUTDOWN SECTION SHDN Device On Device Off ISHVDR ISHVCC Drivers shutdown current Devices shutdown current 1.2 SOFT START SECTION ISS Soft Start current Active Soft start and voltage CURRENT LIMIT AND ZERO CURRENT COMPARATOR ILIM input bias current Zero Crossing Comparator offset Phase-gnd DKILIM Current limit factor RILIM = 2KΩ to 200KΩ 4.6 -2 1.6 1.8 5 5.4 2 2 VSS = 0.4V 4 300 400 6 500 3/23 L6997 ELECTRICAL CHARACTERISTICS (continued) (VCC = VDR = 3.3V; Tamb = 0°C to 85°C unless otherwise specified) Symbol ON TIME Ton On time duration VREF=VSENSE OSC=125mV VREF=VSENSE OSC=250mV VREF=VSENSE OSC=500mV OFF TIME TOFFMIN Minimum off time KOSC/TOFFMIN VOLTAGE REFERENCE VREF Voltage Accuracy 0µA < IREF < 100µA 0.594 0.6 0.606 V OSC=250mV 0.3 600 0.33 ns 720 370 210 800 420 240 880 470 270 ns ns ns Parameter Test Condition Min. Typ. Max. Unit PWM COMPARATOR Input voltage offset IFB Input Bias Current -2 20 +2 mV nA INTEGRATOR INT INT Over Voltage Clamp Under Voltage Clamp Integrator Input Offset Voltage VSENSE-VREF IVSENSE Input Bias Current VSENSE = VCC VSENSE = GND 0.62 0.45 -4 20 0.75 0.55 0.88 0.65 -4 V V mV nA GATE DRIVERS High side rise time High side fall time Low side rise time Low side fall time PGOOD UVP/OVP PROTECTIONS OVP UVP PGOOD PGOOD VPGOOD Over voltage threshold Under voltage threshold Upper threshold (VSENSE-VREF) Lower threshold (VSENSE-VREF) VSENSE rising VSENSE falling ISink=2mA with respect to VREF 118 67 110 85 121 70 112 88 0.2 124 73 116 91 0.4 % % % % V VDR=3.3V; C=7nF HGATE - PHASE from 1 to 3V VDR=3.3V; C=14nF LGATE from 1 to 3V 50 50 50 50 90 100 90 90 ns ns ns ns 4/23 Vcc SHDN + VSENSE 1.12 VREF undervoltage comparator VSENSE 0.6 VREF IC enable pgood comparators + VSENSE VCC VSENSE 0.925 VREF HGATE BOOT V(LGATE)