LM26001_08

LM26001 1.5A Switching Regulator with High Efficiency Sleep Mode May 29, 2008 LM26001 1.5A Switching Regulator with High Efficiency Sleep Mode General Description The LM26001 is a switching regulator designed for the high efficiency requirements of applications with stand-by modes. The device features a low-current sleep mode to maintain efficiency under light-load conditions and current-mode control for accurate regulation over a wide input voltage range. Quiescent current is reduced to 10 µA typically in shutdown mode and less than 40 µA in sleep mode. Forced PWM mode is also available to disable sleep mode. The LM26001 can deliver up to 1.5A of continuous load current with a fixed current limit, through the internal N-channel switch. The part has a wide input voltage range of 4.0V to 38V and can operate with input voltages as low as 3V during line transients. Operating frequency is adjustable from 150 kHz to 500 kHz with a single resistor and can be synchronized to an external clock. Other features include Power good, adjustable soft-start, enable pin, input under-voltage protection, and an internal bootstrap diode for reduced component count. Features ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ High efficiency sleep mode 40 µA typical Iq in sleep mode 10 µA typical Iq in shutdown mode 3.0V minimum input voltage 4.0V to 38V continuous input range 1.5% reference accuracy Cycle-by-cycle current limit Adjustable Frequency (150 kHz to 500 kHz) Synchronizable to an external clock Power Good Flag Forced PWM function Adjustable Soft-start TSSOP-16 exposed pad package Thermal Shut Down Applications ■ ■ ■ ■ ■ Automotive Telematics Navigation systems In-Dash Instrumentation Battery Powered Applications Stand-by power for home gateways/set-top boxes Typical Application Circuit 20179401 © 2008 National Semiconductor Corporation 201794 www.national.com LM26001 Connection Diagram 20179402 Top View 16-Lead Plastic TSSOP Ordering Information Order Number LM26001MXA LM26001MXAX Package Type TSSOP-16EXP TSSOP-16EXP Package Drawing MXA16A MXA16A Package Marking LM26001EM LM26001EM Supplied As 92 Units of Rail 2500 Units of Tape and Reel Pin Descriptions Pin # 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 EP Pin Name VIN VIN PGOOD EN SS COMP FB GND FREQ FPWM SYNC VBIAS VDD BOOT SW SW EP Power supply input Power supply input Power Good pin. An open drain output which goes high when the output voltage is greater than 92% of nominal. Enable is an analog level input pin. When pulled below 0.8V, the device enters shutdown mode. Soft-start pin. Connect a capacitor from this pin to GND to set the soft-start time. Compensation pin. Connect to a resistor capacitor pair to compensate the control loop. Feedback pin. Connect to a resistor divider between Vout and GND to set output voltage. Ground Frequency adjust pin. Connect a resistor from this pin to GND to set the operating frequency. FPWM is a logic level input pin. For normal operation, connect to GND. When pulled high, sleep mode operation is disabled. Frequency synchronization pin. Connect to an external clock signal for synchronized operation. SYNC must be pulled low for non-synchronized operation. Connect to an external 3V or greater supply to bypass the internal regulator for improved efficiency. If not used, VBIAS should be tied to GND. The output of the internal regulator. Bypass with a minimum 1.0 µF capacitor. Bootstrap capacitor pin. Connect a 0.1µF minimum ceramic capacitor from this pin to SW to generate the gate drive bootstrap voltage. Switch pin. The source of the internal N-channel switch. Switch pin. The source of the internal N-channel switch. Exposed Pad thermal connection. Connect to GND. Description www.national.com 2 LM26001 Absolute Maximum Ratings (Note 1) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Voltages from the indicated pins to GND: VIN -0.3V to 40V SW (Note 7) -0.5V to 40V VDD -0.3V to 7V VBIAS -0.3V to 10V FB -0.3V to 6V BOOT SW-0.3V to SW+7V PGOOD -0.3V to 7V FREQ -0.3V to 7V SYNC -0.3V to 7V EN -0.3V to 40V FPWM -0.3V to 7V SS Storage Temperature Power Dissipation (Note 2) Recommended Lead Temperature Vapor Phase (70s) Infrared (15s) ESD Susceptibility (Note 3) Machine Model Human Body Model Charged Device Model -0.3V to 7V -65°C to +150°C 2.6 W 215°C 220°C 200V 2KV 1kV (Note 1) −40°C to 125°C 3.0V to 38V Operating Ratings Operating Junction Temp. Supply Voltage (Note 4) Specifications in standard type are for TJ = 25°C only, and limits in boldface type apply over the junction temperature (TJ) range of -40°C to +125°C. Unless otherwise stated, Vin=12V. Minimum and Maximum limits are guaranteed through test, design, or statistical correlation. Typical values represent the most likely parametric norm at TJ = 25°C, and are provided for reference purposes only. (Note 5) Symbol System ISD (Note 6) Iq_Sleep_VB (Note 6) Iq_Sleep_VDD Iq_PWM_VB Iq_PWM_VDD IBIAS_Sleep (Note 6) IBIAS_PWM VFB IFB ΔVOUT/ΔVIN ΔVOUT/ΔIOUT VDD ISS_Source Vbias_th Switching RDS(ON) Isw_off fsw VFREQ fSW range VSYNC Switch on Resistance Switch off state leakage current Switching Frequency FREQ voltage Switching Frequency range Sync pin threshold Sync pin hysteresis ISYNC FSYNC_UP SYNC leakage current Upper frequency synchronization range As compared to nominal fSW SYNC rising SYNC falling 0.8 150 1.2 1.1 114 6 +30 mV nA % Isw = 1A Vin = 38V, VSW = 0V RFREQ = 62k, 124k, 240k 1.0 500 1.6 0.12 0.2 0.002 0.42 5.0 ±10 Ω µA % V kHz V Shutdown Current Quiescent Current Quiescent Current Quiescent Current Quiescent Current Bias Current Bias Current Feedback Voltage FB Bias Current Vout line regulation Vout load regulation VDD output voltage Soft-start source current VBIAS On Voltage Specified at IBIAS = 92.5% of full value 5V < Vin