LT1506CS8-3.3 Linear Technology, LT1506CS8-3.3 Datasheet
LT1506CS8-3.3
Specifications of LT1506CS8-3.3
Available stocks
Related parts for LT1506CS8-3.3
LT1506CS8-3.3 Summary of contents
Page 1
... There is the optional function of shutdown or synchronization. A shutdown signal reduces supply current Synchronization allows an external logic level sig- nal to increase the internal oscillator from 580kHz to 1MHz. , LTC and LT are registered trademarks of Linear Technology Corporation. D2 1N914 C2 0.68 F ...
Page 2
... V = 3.7V FB SENSE Duty Cycle = 0 V Open 2. 2.9V SENSE DC = 80% ORDER PART NUMBER TOP VIEW LT1506CS8 2 7 SYNC LT1506CS8-3 SHDN LT1506IS8 LT1506IS8-3.3 S8 PACKAGE 8-LEAD PLASTIC SO S8 PART MARKING 1506 150633 MIN TYP MAX 2.39 2.42 2.45 2.36 2.48 3.25 3.3 3 ...
Page 3
ELECTRICAL CHARACTERISTICS 5V 1.5V, Boost = PARAMETER Switch On Resistance (Note 7) Maximum Switch Duty Cycle Switch Frequency Switch Frequency Line Regulation Frequency Shifting Threshold on FB Pin ...
Page 4
LT1506 W U TYPICAL PERFORMANCE CHARACTERISTICS Minimum Input Voltage with 3.3V Output 4.7 4.5 4.3 4.1 3.9 3.7 3.5 3 100 1000 LOAD CURRENT (mA) 1506 G12 Shutdown Pin Bias Current –500 AT 0.37V SHUTDOWN THRESHOLD. AFTER SHUTDOWN, ...
Page 5
W U TYPICAL PERFORMANCE CHARACTERISTICS Frequency Foldback 500 400 SWITCHING FREQUENCY 300 200 100 FEEDBACK PIN CURRENT 0 0 0.5 1.0 1.5 2.0 2.5 FEEDBACK PIN VOLTAGE (V) 1506 G10 Maximum Load Current OUT 4.4 L= ...
Page 6
LT1506 PIN FUNCTIONS FB/SENSE: The feedback pin is used to set output voltage using an external voltage divider that generates 2.42V at the pin with the desired output voltage. The fixed voltage (-3.3) parts have the divider ...
Page 7
W BLOCK DIAGRAM The LT1506 is a constant frequency, current mode buck converter. This means that there is an internal clock and two feedback loops that control the duty cycle of the power switch. In addition to the normal error ...
Page 8
LT1506 U U APPLICATIONS INFORMATION FEEDBACK PIN FUNCTIONS The feedback (FB) pin on the LT1506 is used to set output voltage and provide several overload protection features. The first part of this section deals with selecting resistors to set output ...
Page 9
U U APPLICATIONS INFORMATION The internal circuitry which forces reduced switching frequency also causes current to flow out of the feedback pin when output voltage is low. The equivalent circuitry is shown in Figure completely off during ...
Page 10
... After making an initial choice, consider the secondary things like output voltage ripple, second sourcing, etc. Use the experts in the Linear Technology’s applica- tions department if you feel uncertain about the final choice. They have experience with a wide range of inductor types and can tell you about the latest devel- opments in low profile, surface mounting, etc ...
Page 11
U U APPLICATIONS INFORMATION Table 2 SERIES VENDOR/ VALUE DC CORE RESIS- PART NO (Amps) TYPE TANCE( ) Coiltronics CTX2-1 2 4.1 Tor 0.011 CTX5-4 5 4.4 Tor 0.019 CTX8-4 8 3.5 Tor 0.020 CTX2-1P 2 3.4 Tor ...
Page 12
LT1506 U U APPLICATIONS INFORMATION Ceramic Capacitors Higher value, lower cost ceramic capacitors are now available in smaller case sizes. These are ideal for input bypassing because of their high ripple rating and tolerance to turn-on surges. As output capacitors, ...
Page 13
U U APPLICATIONS INFORMATION and does not fall to less than 1/3 of nominal output voltage, foldback will not take effect. With the overloaded condi- tion, output current will increase to a typical value of 5.7A, determined by peak switch ...
Page 14
LT1506 U U APPLICATIONS INFORMATION INPUT Keep the connections from the resistors to the shutdown pin short and make sure that interplane or surface capaci- tance to the switching nodes are minimized. If high resistor ...
Page 15
U U APPLICATIONS INFORMATION from the switch node. Also note that the high current ground path of the catch diode and input capacitor are kept very short and separate from the analog ground line. The high speed switching current path ...
Page 16
LT1506 U U APPLICATIONS INFORMATION PARASITIC RESONANCE Resonance or “ringing” may sometimes be seen on the switch node (see Figure 7). Very high frequency ringing following switch rise time is caused by switch/diode/input capacitor lead inductance and diode capacitance. Schot- ...
Page 17
U U APPLICATIONS INFORMATION The term inside the radical has a maximum value of 0.5 when input voltage is twice output, and stays near 0.5 for a relatively wide range of input voltages common practice therefore to simply ...
Page 18
LT1506 U U APPLICATIONS INFORMATION formulas show how to calculate each of these losses. These formulas assume continuous mode operation, so they should not be used for calculating efficiency at light load currents. Switch loss ...
Page 19
U U APPLICATIONS INFORMATION 40 GAIN 20 0 PHASE –20 –40 10 100 1k 10k FREQUENCY (Hz) Figure 10. Response from V C Error amplifier transconductance phase and gain are shown in Figure 11. The error amplifier can be modeled ...
Page 20
LT1506 U U APPLICATIONS INFORMATION G = Transconductance of power stage = 5.3A Error amplifier transconductance = 2(10 MA ESR = Output capacitor ESR 2.42 = Reference voltage With and ESR = 0.03 , ...
Page 21
U U APPLICATIONS INFORMATION ADJUSTABLE INPUT SUPPLY 10mV/DIV 5A/DIV 0.2ms/DIV Figure 14. Loop Stability Check The output of the regulator contains both the desired low frequency transient information and a reasonable amount of high frequency (500kHz) ripple. The ripple makes ...
Page 22
LT1506 U U APPLICATIONS INFORMATION converters 120 out of phase with each other reduces input and output ripple currents. This reduces the ripple rating, size and cost of filter capacitors. Current Sharing/Split Input Supplies Current sharing is accomplished by joining ...
Page 23
... Figure 16. Buck Converter with Adjustable Soft Start Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen- tation that the interconnection of its circuits as described herein will not infringe on existing patent rights. ...
Page 24
... LT1372/LT1377 500kHz and 1MHz High Efficiency 1.5A Switching Regulators LT1374 High Efficiency Step-Down Switching Regulator LT1435/LT1436 High Efficiency Step-Down Converter Burst Mode is a trademark of Linear Technology Corporation. Linear Technology Corporation 24 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 www.linear-tech.com U Dimensions in inches (millimeters) unless otherwise noted ...