SEMTECH SC4205

SC4205 Very Low Dropout 1 Amp Regulator With Enable POWER MANAGEMENT Description Features The SC4205 is a high performance positive voltage ‹ 350mV dropout @ 1A regulator designed for use in applications requiring very ‹ Adjustable output from 1.2V to 4.8V low dropout voltage at up to 1 Amp. Since it has ‹ 2.5V and 1.8V options (adjustable externally superior dropout characteristics compared to regular using resistors) LDOs, it can be used to supply 2.5V on motherboards or ‹ Over current and over temperature protection 2.8V on peripheral cards from the 3.3V supply thus ‹ Enable pin allowing the elimination of costly heatsinks. Additionally, ‹ 10µA quiescent current in shutdown the SC4205 has an enable pin to further reduce power ‹ Low reverse leakage (output to input) dissipation while shut down. The SC4205 provides ex- ‹ Surface mount and through-hole packages cellent regulation over variations in line, load and tem- ‹ Full industrial temperature range perature. ‹ Available in SOIC-8EDP package The SC4205 is available in the SOIC-8EDP package with Applications internally preset outputs that are also adjustable using external resistors. ‹ Battery powered systems ‹ Motherboards ‹ Peripheral cards ‹ Network cards ‹ Set Top Boxes ‹ Medical Equipment ‹ Notebook Computers Typical Application Circuits SC4205 4 5 NC NC 3 6 VIN VIN VO VO 2 7 EN ADJ ENABLE 1 8 R1 1.2 (R1 + R2) NC GND VO = Volts R2 U1 C1 C2 R2 SC4205 SC4205 4 5 4 5 NC NC NC NC 3 6 3 6 VIN VO VIN VO VIN VO VIN VO 2 7 2 7 EN ADJ EN ADJ ENABLE ENABLE 1 8 1 8 NC GND NC GND U1 U1 C1 C2 C1 C2 Notes: (1) Maximum VO setpoint for 1.8V parts = 5.4V. (2) This device is designed to operate with ceramic input and output capacitors. Revision: June 28, 2004 1 www.semtech.com SC4205 POWER MANAGEMENT Absolute Maximum Ratings Exceeding the specifications below may result in permanent damage to the device, or device malfunction. Operation outside of the parameters specified in the Electrical Characteristics section is not implied. Parameter Sx ymbol Ms a Unit Input Voltage V 7V IN Power Dissipation PIW nternally Limited D (1) Thermal Resistance Junction to Ambient SOIC-8EDP 3W 6 °C/ θ JA (1) Thermal Resistance Junction to Case SOIC-8EDP 5W .5 °C/ θ JC Operating Ambient Temperature Range T -C 40 to +85 ° A Operating Junction Temperature Range T -C 40 to +150 ° J Storage Temperature Range T -C 65 to +150 ° STG Lead Temperature (Soldering) 10 Sec. T 3C 00 ° LEAD ESD Rating (Human Body Model) V 4V k ESD Note: (1) 1 square inch of FR-4, double sided, 1 oz. minimum copper weight. Electrical Characteristics Unless specified: V = V . Adjustable Option (V > V ): V = 2.2V to 5.5V and I = 10µA to 1A. EN IN ADJ TH(ADJ) IN O Fixed Options (V = GND): V = (V + 0.5V) to 5.5V and I = 0A to 1A. Values in bold apply over T = -40°C to 125°C ADJ IN O O J Pl arameter Ss ymbo Tn estCondition Mp i Tx y Ms a Unit VIN OV perating Voltage Range 25 .2 5. V IN QI uiescent Current V=5 3.3V 0.7 1.75 mA Q IN V = 5.5V, V=0 0V 1 35 µA IN EN VO (1) Output Voltage -V 1% +V 1% O V I = 10mA O O (Internal Fixed Voltage) -% 2% +2 (1) Line Regulation REG I=5 10mA 0.03 0.3 % (LINE) OUT (1) Load Regulation REG I=2 10mA to 1A 0. 0.4 % (LOAD) OUT (1)(2) Dropout Voltage V I=5 10mA 20 . 1 D O mV 20 I=0 500mA 90 30 O mV 400 I=0 1A 10 8 40 O mV 500  2004 Semtech Corp. 2 www.semtech.com SC4205 POWER MANAGEMENT Electrical Characteristics (Cont.) Unless specified: V = V . Adjustable Option (V > V ): V = 2.2V to 5.5V and I = 10µA to 1A. EN IN ADJ TH(ADJ) IN O Fixed Options (V = GND): V = (V + 0.5V) to 5.5V and I = 0A to 1A. Values in bold apply over T = -40°C to 125°C ADJ IN O O J Pl arameter Ss ymbo Tn estCondition Mp i Tx y Ms a Unit VO(Cont.) (3) Minimum Load Current I 1 10 µA O CI urrent Limit 1.6 1.33 3.5 A CL ADJ (1) Reference Voltage V V = 2.2V, V = V , I=8 10mA 10 .1812 .201V .21 REF IN ADJ OUT O 14 .176 1.22 (4) Adjust Pin Current I V = V 30 200 nA ADJ ADJ REF (5) Adjust Pin Threshold V 0.05 0.20 0.40 V TH(ADJ) EN EI nable Pin Current V = 0V, V=5 3.3V 1. 10 µA EN EN IN EV nable Pin Threshold V = 3.3V 1.6 V IH IN V V = 3.3V 0.4 IL IN Over Temperature Protection HT igh Trip level 1C 70 ° HI HT ysteresis 2C 0 ° HYST Notes: (1) Low duty cycle pulse testing with Kelvin connections required. (2) Defined as the input to output differential at which the output voltage drops to 1% below the value measured at a differential of 0.7V. (3) Required to maintain regulation. Voltage set resistors R1 and R2 are usually utilized to meet this requirement. Adjustable versions only. (4) Guaranteed by design. (5) When V exceeds this threshold, the “Sense Select” switch disconnects the internal feedback chain from ADJ the error amplifier and connects V instead. ADJ  2004 Semtech Corp. 3 www.semtech.com SC4205 POWER MANAGEMENT Ordering Information Pe artNumber PT ackag Temp.Range ( ) A (1)(2) SC4205IS-X.XTR O S5 OIC-8EDP -40 to +8 C (1)(2)(3) SC4205IS-X.XTRT Sd C4205EVB Evaluation Boar Notes: (1) Where -X.X denotes voltage options. Available voltages are: 2.5V and 1.8V. Output voltage can be adjusted using external resistors, see Pin Descriptions on page 5. (2) Only available in tape and reel packaging. A reel contains 2500 devices. (3) Lead free product Pin Configuration Top View Bottom View GND NC GND GND 8 1 NC ADJ 7 Exposed EN ADJ 2 EN Die Pad 6 VIN VO 3 VIN VO 5 4 NC NC NC NC SOIC-8EDP SOIC-8EDP Pin Descriptions Pn in Name Pin Desciptio ADJ This pin, when grounded, sets the output voltage to that set by the internal feedback resistors. If external feedback resistors are used, the output voltage will be (See Application Circuits on page 1): 1.200 (R1 + R2) VO = Volts R2 EN Enable Input. Pulling this pin below 0.4V turns the regulator off, reducing the quiescent current to a fraction of its operating value. The device will be enabled if this pin is left open. Connect to VIN if not being used. GND Reference ground. Note: The GND pin and the exposed die pad must be connected together at the IC pin. Use the exposed die pad on the device for heatsinking. VIN Input voltage. For regulation at full load, the input to this pin must be between (VO + 0.5V) and 5.5V. Minimum VIN = 2.2V. V. O The pin is the power output of the device  2004 Semtech Corp. 4 www.semtech.com SC4205 POWER MANAGEMENT Block Diagram  2004 Semtech Corp. 5 www.semtech.com SC4205 POWER MANAGEMENT Applications Information Thermal Considerations Introduction The SC4205 is intended for applications such as The power dissipation in the SC4205 is approximately graphics cards where high current capability and very low equal to the product of the output current and the input to output voltage differential: dropout voltage are required. It provides a very simple, low cost solution that uses very little pcb real estate. Additional features include an enable pin to allow for a P ≈() VIN −VOUT •I D O very low power consumption standby mode, and a fully adjustable output. The absolute worst-case dissipation is given by: Component Selection P =() VIN −VOUT •I +VIN •I D(MAX) (MAX) (MIN) O(MAX) (MAX) Q(MAX) Input capacitor: a 4.7µF ceramic capacitor is For a typical scenario, V = 3.3V ± 5%, V = 2.8V and recommended. This allows for the device being some IN OUT I = 1A, therefore: distance from any bulk capacitance on the rail. O Additionally, input droop due to load transients is reduced, V = 3.465V, V = 2.744V and I = 1.75mA, improving load transient response. Additional capacitance IN(MAX) OUT(MIN) Q(MAX) may be added if required by the application. Thus P = 727mW. D(MAX) Output capacitor: a minimum bulk capacitance of 2.2µF, Using this figure, and assuming T = 70°C, we can along with a 0.1µF ceramic decoupling capacitor is A(MAX) calculate the maximum thermal impedance allowable to recommended. Increasing the bulk capacitance will maintain T ≤ 150°C: improve the overall transient response. The use of J multiple lower value ceramic capacitors in parallel to achieve the desired bulk capacitance will not cause () T −T () 150 −70 J(MAX ) A(MAX ) R = = =110°C/W TH(J −A)(MAX ) stability issues. Although designed for use with ceramic P .727 D(MAX ) output capacitors, the SC4205 is extremely tolerant of output capacitor ESR values and thus will also work This should be achievable for the SOIC-8EDP package comfortably with tantalum output capacitors. For refer- using pcb copper area to aid in conducting the heat away, ence, the phase-margin contour of Figure 1 can be used such as one square inch of copper connected to the pins to choose an appropriate output capacitor for a given of the device. Internal ground/power planes and air flow stability requirement. will also assist in removing heat. For higher ambient tem- peratures it may be necessary to use additional copper Noise immunity: in very electrically noisy environments, area. it is recommended that 0.1µF ceramic capacitors be placed from IN to GND and OUT to GND as close to the device pins as possible. External voltage selection resistors: the use of 1% resistors, and designing for a current flow ≥ 10µA is recommended to ensure a well regulated output (thus R2 ≤ 120kΩ).  2004 Semtech Corp. 6 www.semtech.com SC4205 POWER MANAGEMENT Outline Drawing - SOIC-8EDP Land Pattern - SOIC-8EDP  2004 Semtech Corp. 7 www.semtech.com SC4205 POWER MANAGEMENT Contact Information Semtech Corporation Power Management Products Division 200 Flynn Road, Camarillo, CA 93012 Phone: (805)498-2111 FAX (805)498-3804  2004 Semtech Corp. 8 www.semtech.com