2A INTERNAL SWITCH OPERATING INPUT VOLTAGE FROM TO 36V OUTPUT VOLTAGE ADJUSTABLE FROM TO 35V LOW DROPOUT OPERATION: 100% DUTY CYCLE 250KHz INTERNALLY FIXED FREQUENCY VOLTAGE FEEDFORWARD ZERO LOAD CURRENT OPERATION INTERNAL CURRENT LIMITING PROTECTION AGAINST FEEDBACK DISCONNECTION THERMAL SHUTDOWN
DESCRIPTION The is a step down monolithic power switching regulator with a minimum switch current limit it is able to deliver more than 1.5A DC current to the load depending on the application conditions. The output voltage can be set from to 35V. The device uses an internal P-Channel D-MOS transistor (with a typical Rdson 250m) as switching element to minimize the size of the external components. An internal oscillator fixes the switching frequency at 250KHz. Having a minimum input voltage of 4.4V only, it is particularly suitable for 5V bus, available in all computer related applications. Pulse by pulse current limit with the internal frequency modulation offers an effective constant current short circuit protection.
APPLICATIONS: s CONSUMER: STB, DVD, TV, VCR,CAR RADIO, LCD MONITORS s NETWORKING: XDSL, MODEMS,DC-DC MODULES s COMPUTER: PRINTERS, AUDIO/GRAPHIC CARDS, OPTICAL STORAGE, HARD DISK DRIVE s INDUSTRIAL: CHARGERS, CAR BATTERY DC-DC CONVERTERS
N° Pin OUT GND COMP FB VCC Regulator Output. Ground. E/A output for frequency compensation. Feedback input. Connecting directly to this pin results in an output voltage 1.23V. An external resistive divider is required for higher output voltages. Unregulated DC input voltage. Function
Symbol Rth (j-amb) Parameter Thermal Resistance Junction to ambient
Symbol V4, V5 Ptot Tj Tstg Input Voltage Out pin DC voltage Out pin peak voltage = 0.1µs Maximum output current Analog pins Power dissipation at Tamb 70°C Operating junction temperature range Storage temperature range Parameter Value to 40 int. limit. W °C Unit V
ELECTRICAL CHARACTERISTICS (Tj = 25°C, VCC = 12V, unless otherwise specified.) Specification Referred to Tj from to 125°C.
Symbol VCC RDSON Il fs Parameter Operating input voltage range Mosfet on Resistance Maximum limiting current Switching frequency VCC to 36V Test Condition = 1.5A Duty cycle DYNAMIC CHARACTERISTICS (see test circuit V5 Voltage feedback 4.4V < VCC = 5V, VCC = 12V Min. Typ. Max. Unit V A KHz %
DC CHARACTERISTICS Iqop Iq Total operating quiescent current Quiescent current Duty Cycle = 0; VFB 1.5V mA
ERROR AMPLIFIER VOH VOL Io source Io sink Ib High level output voltage Low level output voltage Source output current Sink output current Source bias current DC open loop gain gm Transconductance RL = Icomp to 0.1mA VCOMP 1.9V 50 VFB = 1V VFB = 1.5V VCOMP = 1.9V; VFB = 1V VCOMP = 1.9V; VFB dB mS
Note (1): Specification over the +125 Tj Temperature range are assured by design, characterization and statistical correlation.