ISSUED DATE :2006/03/08 REVISED DATE :2006/05/17B GSC2596M 150 KHz, 2A PWM Step-Down DC/DC Converter Description The GSC2596M series of regulators are monolithic integrated circuit that provides all active functions for a step-down (buck) switching regulator, capable of driving 2A load with excellent line and load regulation. These devices are available in fixed output voltages of 3.3v, 5v, 12v and an adjustable output version. The GSC2596M series operate at a switching frequency of 150 kHz; thus allowing smaller sized filter components than what would be needed with lower frequency switching regulators. The chips are available in a standard 8-lead SOP-8 package. Other feature include a guaranteed 4% to tolerance on output voltage under specified input voltages and output load conditions. The 150 kHz 15% is on the oscillator frequency. External shutdown is included, featuring 80uA (Typ.) standby current. The output switch includes cycle-by cycle current limiting, as well as thermal shutdown for full protection under fault conditions. Features 3.3V, 5.0V, 12V and adjustable output versions Guaranteed 2A output current Operating voltage can be up to 22V 150kHz fixed frequency internal oscillator Built-in TTL On/Off control TTL Shutdown Capability Uses readily available standard inductors Thermal shutdown and current limit protection Applications High-efficiency step-down regulator One-ch switching regulators simple Positive to negative converter Package Dimensions REF. A B C D E F Millimeter Min. Max. 5.80 4.80 3.80 0° 0.40 0.19 6.20 5.00 4.00 8° 0.90 0.25 REF. M H L J K G Millimeter Min. Max. 0.10 0.25 0.35 0.49 1.35 1.75 0.375 REF. 45° 1.27 TYP. Block Diagram GSC2596M Page: 1/6 ISSUED DATE :2006/03/08 REVISED DATE :2006/05/17B Pin Function Pin Name Pin# Function This is the positive input supply for the IC switching regulator. A suitable input bypass capacitor must be present at this pin to minimize voltage transients and to supply the switching current needed by regulator. Internal switch. The voltage at this pin switches between (+V IN - V SAT) and approximately -0.5V, with a duty cycle of approximately V OUT/V IN. To minimize coupling to sensitive circuitry, the PC board copper area connected to this pin should be keep to a minimum. VIN 1 Output 2 Feedback(FB) 3 Senses the regulated output voltage to complete the feedback loop. 4 Allows the switching regulator circuit to be shutdown using logic level signals. Thus drop the total input supply current to approximately 150 A. Pulling this pin below a threshold voltage of approximately 1.3V turns the regulator on, and pulling this pin above 1.3V (up to a maximum of 18V) shuts the regulator down. If this shutdown feature is not needed, ON/OFF pin can be wired to the ground pin. ON/OFF(SD) Ground 5,6,7,8 Circuit ground Absolute Maximum Ratings Parameter Symbol VCC VSD VFB VOUT PD TST TOP VOP Supply Voltage ON/OFF Pin Input Voltage Feedback Pin Voltage Output Voltage to ground Power Dissipation Storage Temperature Operating temperature Operating Voltage Ratings 24 -0.3 ~ +18 -0.3 ~ +18 -1 Internally Limited -65 ~ +150 -40 ~ +125 +4.5 ~ +22 Unit V V V V W V GSC2596M Electrical Characteristics Specifications in boldface type are for full operating temperature range. The other type are for TJ=25 Parameter Output Feedback Symbol VFB Efficiency Conditions 5 VIN 22V, 0.2A ILOAD 2A VOUT=3V VIN=12V, ILOAD=2A, VOUT=3V . Min Typ Max Unit 1.180/1.168 1.230 1.280/1.292 V 76 % GSC2596M-33 Electrical Characteristics Specifications in boldface type are for full operating temperature range. The other type are for TJ=25 Parameter Output Feedback Symbol VFB Efficiency Conditions 5.5V VIN 22V 0.2A ILOAD 2A VIN=12V, ILOAD=2A . Min Typ Max Unit 3.168/3.135 3.3 3.432/3.465 V 78 % GSC2596M-50 Electrical Characteristics Specifications in boldface type are for full operating temperature range. The other type are for TJ=25 Parameter Output Feedback Symbol VFB Efficiency Conditions 8V VIN 22V 0.2A ILOAD 2A VIN=12V, ILOAD=2A . Min Typ Max Unit 4.80/4.75 5.0 5.20/5.25 V 83 % GSC2596M-12 Electrical Characteristics Specifications in boldface type are for full operating temperature range. The other type are for TJ=25 Parameter Output Feedback Efficiency GSC2596M Symbol VFB Conditions 15V VIN 22V 0.2A ILOAD 2A VIN=16V, ILOAD=2A . Min Typ Max Unit 11.52/11.40 12 12.48/12.60 V 90 % Page: 2/6 ISSUED DATE :2006/03/08 REVISED DATE :2006/05/17B All Output Voltage Version Electrical Characteristics Specifications in boldface type are for full operating temperature range. The other type are for TJ=25 Parameter Feedback bias current Oscillator frequency Symbol IFB Conditions VFB=1.3V (adjustable version only) FOSC . Min 127/110 Typ -10 150 Max -50/-100 173/173 Unit nA kHz Oscillator frequency of short circuit protect FSCP When current limit occurred and VFB<0.5V, TA=25 . 5 15 25 kHz Saturation voltage VSAT ILOAD=2A No outside circuit VFB=0V force drive on - 1.25 1.4/1.5 V VFB=0V force drive on VFB=12V force drive off - 100 0 - % 3 - - A - - -200 uA - 10 mA mA 2.0 -5 5 - Max. duty cycle (ON) Max. duty cycle (OFF) DC Current limit ICL Output leakage current IL IQ Peak current No outside circuit VFB=0V force drive on Output=0V, No outside circuit VFB=12V force drive off Output=-1V, VIN=22V VFB=12V force drive off ON/OFF pin logic input VIL Low (Regulator ON) Threshold Voltage ON/OFF pin Logic input current VIH High (Regulator OFF) IH VLOGIC=2.5V ( Regulator OFF) - IL VLOGIC=0.5V ( Regulator ON) - -0.1 -1 - 150 200 - 15 - - 70 - Quiescent current ON/OFF pin input current Standby quiescent current ISTBY ON/OFF pin=5V, VIN=12V JC Thermal Resistance JA Junction to Case Junction to Ambient with copper 2 area of approximately 3 in - 0.6 V -0.01 uA uA /W Unless otherwise specified, V IN=12V for 3.3V, 5V, adjustable version and V IN=18V for the 12V version. ILOAD=0.5A Function Description The SOP-8 package needs a heat sink under most conditions. The size of the heat sink depends on the input voltage, the output voltage, the load current and the ambient temperature. The GSC2596M junction temperature rises above ambient temperature with a 2A load and different input and output voltages. The data for these curves was taken with the GSC2596M operating as a buck-switching regulator in an ambient temperature of 25 (still air). These temperature rise numbers are all approximate and there are many factors that can affect these temperatures. Higher ambient temperatures require more heat sinking. For the best thermal performance, wide copper traces and generous amounts of printed circuit board copper should be used in the board layout. (One exception to this is the output (switch) pin, which should not have large areas of copper.) Large areas of copper provide the best transfer of heat (lower thermal resistance) to the surrounding air, and moving air lowers the thermal resistance even further. Package thermal resistance and junction temperature rise numbers are all approximate, and there are many factors will affect these numbers. Some of these factors include board size, shape, thickness, position, location and even board temperature. Other factors are, trace width, total printed circuit copper area, copper thickness, single or double-sided, multi-layer board and the amount of solder on the board. The effectiveness of the PC board to dissipate heat also depends on the size, quantity and spacing of other components on the board, as well as the surrounding air is still or moving. Furthermore, some of these components such as the catch diode will add heat to the PC board and the heat can vary as the input voltage changes. For the inductor, depending on the physical size, type of core material and the DC resistance, it could either act as a heat sink taking heat away from the board, or it could add heat to the board. GSC2596M Page: 3/6 ISSUED DATE :2006/03/08 REVISED DATE :2006/05/17B Typical Application Circuit (1)Fixed Type Circuit (2)Adjustable Type Circuit (3)Delay Start Circuit GSC2596M Page: 4/6 ISSUED DATE :2006/03/08 REVISED DATE :2006/05/17B Typical Performance Characteristics GSC2596M Page: 5/6 ISSUED DATE :2006/03/08 REVISED DATE :2006/05/17B Important Notice: All rights are reserved. Reproduction in whole or in part is prohibited without the prior written approval of GTM. GTM reserves the right to make changes to its products without notice. GTM semiconductor products are not warranted to be suitable for use in life-support Applications, or systems. GTM assumes no liability for any consequence of customer product design, infringement of patents, or application assistance. Head Office And Factory: Taiwan: No. 17-1 Tatung Rd. Fu Kou Hsin-Chu Industrial Park, Hsin-Chu, Taiwan, R. O. C. TEL : 886-3-597-7061 FAX : 886-3-597-9220, 597-0785 China: (201203) No.255, Jang-Jiang Tsai-Lueng RD. , Pu-Dung-Hsin District, Shang-Hai City, China TEL : 86-21-5895-7671 ~ 4 FAX : 86-21-38950165 GSC2596M Page: 6/6