GM2574 1.5A STEP DOWN VOLTAGE SWITCHING REGULATORS Description Features GM2574 series is designed to provide all the active function for a step-down (buck) switching regulator, and drives a maximum load current as high as 1.5A line and load regulations. GM2574 is available in fixed output voltages of 3.3V, 5V, and a versatile Adjustable output version. These regulators are simple to use and require minimum number of external components. The features include internal frequency compensation and a fixed-frequency oscillator. The GM2574 is high-efficiency replacements for popular three-terminal linear regulators, and is requiring a smaller heat sink or even no need heat sink. GM2574 performs well with standard inductors from most of manufacturers, and simplifying the design of switch-mode power supplies. External shutdown is included with 80 µA (typical) standby current. The output switch has cycle-by-cycle current limiting as well as thermal shutdown for full protection under fault conditions. Standard SOP8 package 3.3V, 5V, and Adjustable output versions Adjustable version output voltage range 1.23V to 37V VOUT accuracy is to ±2% under specified input voltage the output load conditions Input voltage range up to 40V Requires only 4 external components with High efficiency TTL shutdown capability, low power standby mode Built-in thermal shutdown, current limit protection Uses standard inductors 52 kHz fixed frequency internal oscillator GM2574 operates at a switching frequency of 52 kHz which allowing smaller size filter components than what would be needed with lower frequency switching regulators. GM2574 series are available in a standard 8-lead SO package or 8 lead SO package with heat sink. Application Pre-regulator for linear regulators On-card/board switching regulators High-efficiency step-down buck regulator Positive to negative converter (buck-boost) Typical Application Circuits GM2574-5.0 FB 3 1 VIN Output 2 CIN 100µF SD 4 L1 100µH GND 5, 6, 7, 8 D1 1N5822 5V regulated output, COUT 680µF www.gammamicro.com.tw GM2574V1.02 7V – 40V Unregulated DC Input 1 GM2574 1.5A STEP DOWN VOLTAGE SWITCHING REGULATORS Marking Information and Pin Configurations (Top View) SO8 GND GND GND GND GM2574 VVVAYWW VIN VOUT SD FB VVV: 033=3.3V, 050=5.0V, 00A=ADJ A: Assembly / Testing factory code Y: Year WW: Week Ordering Information GM2574V1.02 Ordering Number 2 Output Voltage Package Shipping GM2574-AS8T Adj SOP8 100 Units / Tube GM2574-AS8R Adj SOP8 2500 Units / Reel GM2574-3.3S8T 3.3 SOP8 100 Units / Tube GM2574-3.3S8R 3.3 SOP8 2500 Units / Reel GM2574-5.0S8T 5.0 SOP8 100 Units / Tube GM2574-5.0S8R 5.0 SOP8 2500 Units / Reel GM2574 1.5A STEP DOWN VOLTAGE SWITCHING REGULATORS Absolute Maximum Ratings (Note 1) Rating Value Unit 45 V SD Pin Input Voltage / Feed Back Pin Voltage -0.3 + VIN + 0.3 V Output Voltage to Ground (Steady State) -0.3 + VIN + 0.3 V Internally Limited - 36 ℃/W - 65 to 150 ℃ + 150 ℃ Operating Temperature Range - 40 to 125 ℃ Minimum EDS Rating (Note 2) 2 kV + 260 ℃ Maximum Supply Voltage Power Dissipation Thermal Resistance – Junction to Ambient (θJA) ** 2 square inch of FR-4, double sided, 1oz. minimum copper weight, is recommended Storage Temperature Range Maximum Junction Temperature Lead Temperature (Soldering, 10 sec) Block Diagram FB 3 VIN R2* 1 Regulator With Enable Error Amplifier Comparator Driver 4 SD R1* 5~8 1.23V Reference Gnd 52KHz Oscillator Reset Thermal Shutdown & Current Limit 2 VOUT GM2574V1.02 VOUT = 3.3V, R1 = 2.49K, R2 = 4.18K VOUT = 5.0V, R1 = 2.49K, R2 = 7.57K VOUT = ADJ, R1 = OPEN, R2 = 0Ω 3 GM2574 1.5A STEP DOWN VOLTAGE SWITCHING REGULATORS Electrical Characteristics: GM2574-ADJ (Specifications with standard type face are for T = 25℃, and those with bold face type apply over full Operating Temperature rage) Parameter Condition Output Voltage 4.5V < VIN < 40V, 0.2A < ILOAD < 1.5A Efficiency VIN =12V, ILOAD=1.5A, VOUT = 9V Symbol VOUT Min 1.205 1.180 η Typ 1.230 Max Unit 1.255 V 1.280 88 % Electrical Characteristics: GM2574-3.3 (Specifications with standard type face are for T = 25℃, and those with bold face type apply over full Operating Temperature rage) Parameter Condition Output Voltage 4.5V < VIN < 40V, 0.2A < ILOAD < 1.5A Efficiency VIN =12V, ILOAD=1.5A Symbol VOUT Min 3.163 3.201 η Typ 3.300 Max Unit 3.390 V 3.432 73 % Electrical Characteristics: GM2574-5.0 GM2574V1.02 (Specifications with standard type face are for T = 25℃, and those with bold face type apply over full Operating Temperature rage) 4 Parameter Condition Output Voltage 4.5V < VIN < 40V, 0.2A < ILOAD < 1.5A Efficiency VIN =12V, ILOAD=1.5A Symbol VOUT η Min 4.850 4.800 Typ 5.000 77 Max 5.150 5.200 Unit V % GM2574 1.5A STEP DOWN VOLTAGE SWITCHING REGULATORS Electrical Characteristics: All Output Voltage Versions (Specifications with standard type face are for T = 25℃, and those with bold face type apply over full Operating Temperature rage) Parameter Condition Symbol Min Typ Feedback Bias Current VFB =5V (Adjustable Version Only) Ib - 50 Oscillator Frequency (Note 3) fo 42 52 Saturation Voltage lOUT = 1.5A (Notes 4, 5) VSAT - 1.4 Max Duty Cycle (ON) (Note 5) DC Current Limit Peak Current (Notes 4, 5) lCL 100 Unit nA 500 58 1.8 kHz V 2.0 93 3.6 98 4.5 3.4 Output Leakage Current Max Output =0V (Notes 4, 6) Output = -1V (Notes 4, 6) Quiescent Current (Note 6) Standby Quiescent Current SD Pin = 5V (OFF) Low (ON) lL - 6.9 A 7.5 7.5 2 mA 30 lQ - 5 10 mA lSTBY - 50 200 µA VIH - 1.2 1.0 0.8 SD Pin Logic lnput Level High (OFF) % VIL 2.2 1.4 - V 2.4 VLOGlC = 2.5V (OFF) IH 12 30 VLOGlC = 0.5V (ON) IL 0 10 µA Note 1: Stresses greater than those listed under Maximum Ratings may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operation is not implied. Exposure to absolute maximum rating conditions for extended periods may affect reliability. Note 2: The human body model is a 100pF capacitor discharge through a 1.5KΩ resistor into each pin. Note 3: External components such as the catch diode, inductor, input and output capacitors, and voltage programming resistors can affect switching regulator system performance. Where the GM2574 is used as shown in Figure 1&2 test circuits. Note 4: No diode, inductor or capacitor connected to output pin. Note 5: Feedback pin removed from output and connected to 0V to force the output transistor switch ON. Note 6: Feedback pin removed from output and connected to 12V for the 3.V, 5V and Adj version, to force the output transistor switch OFF. GM2574V1.02 SD Pin lnput Current 5 GM2574 1.5A STEP DOWN VOLTAGE SWITCHING REGULATORS Test Circuit and Layout Guidelines Careful layout is important with any switching regulators. Rapidly switching currents associated with wiring inductance generate voltage transients which can cause problems. To minimize inductance and ground loops, the lengths of the leads indicated by heavy lines in Figure 1&2 below should be kept as short as possible. Single point grounding (as indicated or ground plane construction should be used for best results. When using the Adjustable version, place the programming resistors as close as possible to GM2574, to keep the sensitive feedback wiring short. 3 FB 1 VIN VIN Unregulatedd DC Input L1 100µH GM2574-x.x 5~8 GND CIN 100µF 4 SD 2 VOUT VOUT D1 L O A D COUT 680µF Figure 1 Fixed Ouput Votlage Versions CIN = 100µF, Aluminum Electrolytic COUT = 680µF, 25V, Aluminum Electrolytic D1 = Schottky L1 = 100µH 1 3 FB GM2574-A VIN GM2574V1.02 VIN Unregulatedd DC Input 6 CIN 100µF 5~8 GND 4 SD L1 100µH VOUT 2 VOUT R2 D1 COUT 680µF Figure 2 Adjustable Ouput Votlage Versions CIN = 100µF, Aluminum Electrolytic COUT = 680µF, 25V, Aluminum Electrolytic D1 = Schottky L1 = 100µH VOUT = VREF (1 + R2/R1) where VREF = 1.23V and R1 is between 1K to 5K R1 L O A D GM2574 1.5A STEP DOWN VOLTAGE SWITCHING REGULATORS Package Outline Dimensions – SO 8 0.189 - 0.197 (4.800 - 5.004) 0.228 - 0.244 (5.791 - 6.198) 0.016 - 0.050 (0.406 - 0.270) 0.050 (1.270) TYP 0.150 - 0.157 (3.810 - 3.988) 0.053 - 0.059 (1.346 - 1.753) SEATING PLAN 0.004 - 0.010 (0.012 - 0.254) 0.008 - 0.010 (0.203 - 0.254) 8.0 MAX GM2574V1.02 D 0.014 - 0.020 (0.356 - 0.508) 7 GM2574 1.5A STEP DOWN VOLTAGE SWITCHING REGULATORS Ordering Number GM 2574 A APM Gamma GM2574V1.02 Micro 8 810 6 Circuit Type S8 R Output Voltage Package Type Shipping Type A: Adj 3.3 = 3.3V 5.0 =5.0V S8: SO 8 R: Taping & Reel T: Tube