MP2235SGJ-Z

MP2235S High-Efficiency, 3 A, 16 V, 800 kHz Synchronous Step-Down Converter The Future of Analog IC Technology DESCRIPTION FEATURES The MP2235S is a high-frequency, synchronous, rectified, step-down, switch-mode converter with built-in power MOSFETs. It offers a compact solution to achieve a 3 A continuous output current with excellent load and line regulation over a wide input supply range. The MP2235S has synchronous mode operation for higher efficiency over the output current load range. • • Current mode operation provides fast transient response and eases loop stabilization. Full protection features include over-current protection (OCP) and thermal shutdown (TSD). The MP2235S requires a minimal number of readily available, standard, external components and is available in a space-saving 8-pin TSOT23 package. • • • • • • • • • Wide 4.5 V to 16 V Operating Input Range 120 mΩ/50 mΩ Low RDS(ON) Internal Power MOSFETs High-Efficiency Synchronous Mode Operation Fixed 800 kHz Switching Frequency Synchronizes from a 300 kHz to a 2 MHz External Clock Power-Save Mode at Light Load External Soft-Start Over-Current Protection and Hiccup Thermal Shutdown Output Adjustable from 0.804 V Available in a 8-pin TSOT-23 Package APPLICATIONS • • • • Notebook Systems and I/O Power Digital Set-Top Boxes Flat-Panel Televisions and Monitors Distributed Power Systems All MPS parts are lead-free, halogen-free, and adhere to the RoHS directive. For MPS green status, please visit the MPS website under Quality Assurance. “MPS” and “The Future of Analog IC Technology” are registered trademarks of Monolithic Power Systems, Inc. TYPICAL APPLICATION 100 95 90 85 80 75 VIN=16V VIN=12V VIN=5V 70 65 60 55 50 0.0 MP2235S Rev.1.0 4/15/2015 0.5 1.0 1.5 2.0 2.5 LOAD CURRENT(A) www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2015 MPS. All Rights Reserved. 3.0 1 MP2235S –3 A, 16 V, 800 kHz SYNCHRONOUS STEP-DOWN CONVERTER ORDERING INFORMATION Part Number* MP2235SGJ Package TSOT23-8 Top Marking See Below * For Tape & Reel, add suffix –Z (e.g. MP2235SGJ–Z) TOP MARKING AQA: Product code of MP2235SGJ Y: Year code PACKAGE REFERENCE MP2235S Rev.1.0 4/15/2015 1 8 2 7 3 6 4 5 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2015 MPS. All Rights Reserved. 2 MP2235S –3 A, 16 V, 800 kHz SYNCHRONOUS STEP-DOWN CONVERTER ABSOLUTE MAXIMUM RATINGS (1) Thermal Resistance VIN ................................................-0.3 V to 17 V VSW.........-0.3 V (-5 V for 1.2 V, R2 is then given using Equation (2): R1 R2 = (2) VOUT −1 0.804V The T-type network is highly recommended (see Figure 7). Figure 7—T-type network Table 1 lists the recommended resistor and compensation values for common output voltages. Table 1—Resistor selection for common output voltages(8) VOUT R1 (kΩ) R2 (kΩ) Rt (kΩ) (V) 1 20.5 84.5 34 1.2 30.1 61.9 24 1.8 40.2 32.4 15 2.5 40.2 19.1 6.8 3.3 40.2 13 5.6 5 40.2 7.68 2 NOTES: 8) The recommended parameters are based on an 800 kHz switching frequency; a different input voltage, output inductor value, and output capacitor value may affect the selection of R1, R2, and Rt. For additional component parameters, please refer to the “Typical Application Circuits” section on page 17 and page 18. Selecting the Inductor Use an inductor (1 µH to 22 µH) with a DC current rating at least 25 percent higher than the maximum load current for most applications. For highest efficiency, use an inductor with a DC resistance less than 15 mΩ. For most designs, the inductance value can be derived from Equation (3): MP2235S Rev.1.0 4/15/2015 L1 = VOUT × (VIN − VOUT ) VIN × ΔIL × fOSC (3) Where ΔIL is the inductor ripple current. Choose the inductor ripple current to be approximately 30 percent of the maximum load current. The maximum inductor peak current is calculated using Equation (4): IL(MAX) = ILOAD + ΔIL 2 (4) Use a larger inductor for improved efficiency under light-load conditions—below 100 mA. Selecting the Input Capacitor The input current to the step-down converter is discontinuous, therefore it requires a capacitor to supply the AC current to the step-down converter while maintaining the DC input voltage. Use low ESR capacitors for the best performance. Use ceramic capacitors with X5R or X7R dielectrics for best results because of their low ESR and small temperature coefficients. For most applications, use a 22 µF capacitor. Since C1 absorbs the input switching current, it requires an adequate ripple current rating. The RMS current in the input capacitor can be estimated using Equation (5) and Equation (6): I C1 = ILOAD × VOUT ⎛⎜ VOUT × 1− VIN ⎜⎝ VIN ⎞ ⎟ ⎟ ⎠ (5) The worst case condition occurs at VIN = 2VOUT, where: IC1 = ILOAD 2 (6) For simplification, choose an input capacitor with an RMS current rating greater than half of the maximum load current. The input capacitor can be electrolytic, tantalum, or ceramic. When using electrolytic or tantalum capacitors, add a small, high-quality ceramic capacitor (e.g. 0.1 μF) placed as close to the IC as possible. When using ceramic capacitors, www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2015 MPS. All Rights Reserved. 14 MP2235S –3 A, 16 V, 800 kHz SYNCHRONOUS STEP-DOWN CONVERTER make sure that they have enough capacitance to provide sufficient charge in order to prevent excessive voltage ripple at the input. The input voltage ripple caused by capacitance can be estimated using Equation (7): ΔVIN = ⎛ ⎞ ILOAD V V × OUT × ⎜ 1 − OUT ⎟ fS × C1 VIN ⎝ VIN ⎠ (7) Selecting the Output Capacitor The output capacitor (C2) maintains the DC output voltage. Use ceramic, tantalum, or low ESR electrolytic capacitors. For best results, use low ESR capacitors to keep the output voltage ripple low. The output voltage ripple can be estimated with Equation (8): ΔVOUT = ⎞ VOUT ⎛ VOUT ⎞ ⎛ 1 × ⎜1 − ⎟ ⎟ × ⎜ RESR + fS × L1 ⎝ VIN ⎠ ⎝ 8 × fS × C2 ⎠ (8) Where L1 is the inductor value and RESR is the equivalent series resistance (ESR) value of the output capacitor. For ceramic capacitors, the capacitance dominates the impedance at the switching frequency, and the capacitance causes the majority of the output voltage ripple. For simplification, the output voltage ripple can be estimated with Equation (9): ΔVOUT = ⎛ V ⎞ VOUT × ⎜ 1 − OUT ⎟ VIN ⎠ 8 × fS × L1 × C2 ⎝ 2 (9) For tantalum or electrolytic capacitors, the ESR dominates the impedance at the switching frequency. For simplification, the output ripple can be approximated with Equation (10): ΔVOUT V V ⎛ = OUT × ⎜ 1 − OUT fS × L1 ⎝ VIN ⎞ ⎟ × RESR ⎠ External Bootstrap Diode In particular conditions, the BST voltage may become insufficient. During these conditions, an external bootstrap diode can enhance the efficiency of the regulator and avoid insufficient BST voltage at light-load PFM operation. Insufficient BST voltage is more likely to occur during either of the following conditions: MP2235S Rev.1.0 4/15/2015 VOUT is 5 V or 3.3 V; or z the duty cycle is high: D= VOUT >65% VIN If the BST voltage is insufficient, the output ripple voltage may become extremely large during a light-load condition. If this occurs, add an external BST diode from VCC to BST (see Figure 8). MP2235S Figure 8—Optional external bootstrap diode to enhance efficiency The recommended external BST diode is IN4148, and the BST capacitor value is 0.1 µF to 1 μF. PCB Layout Guidelines (9) Efficient PCB layout is critical to achieve stable operation, especially for VCC capacitor and input capacitor placement. For best results, refer to Figure 9 and follow the guidelines below: 1. Use a large ground plane directly connected to GND. Add vias near GND if the bottom layer is ground plane. 2. Place the VCC capacitor as close as possible to the chip VCC and GND. Make the trace length of VCC pin to the VCC capacitor anode to the VCC capacitor cathode to the chip GND as short as possible. 3. Place the ceramic input capacitor close to IN and GND. Keep the connection of the input capacitor and IN as short and wide as possible. 4. Route SW and BST away from sensitive analog areas such as FB. 5. Place the T-type feedback resistor (R5) close to the chip to ensure the trace (which connects to FB) is as short as possible. (10) The characteristics of the output capacitor affect the stability of the regulation system. The MP2235S can be optimized for a wide range of capacitance and ESR values. z NOTES: 9) The recommended layout is based on Figure 10 on page 17. www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2015 MPS. All Rights Reserved. 15 5 6 7 R3 R5 8 R2 MP2235S –3 A, 16 V, 800 kHz SYNCHRONOUS STEP-DOWN CONVERTER Design Example Table 2 is a design example following the application guidelines for the following specifications: 4 3 2 1 C5 Table 2—Design example VIN VOUT IOUT Top Layer 12 V 3.3 V 3A The detailed application schematic is shown in Figure 11. The typical performance and circuit waveforms have been shown in the “Typical Performance Characteristics” section. For more device applications, please refer to the related evaluation board datasheets. GND EN/SYNC BST SW Vout SenseGND Bottom Layer Figure 9—Recommended PCB layout MP2235S Rev.1.0 4/15/2015 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2015 MPS. All Rights Reserved. 16 MP2235S –3 A, 16 V, 800 kHz SYNCHRONOUS STEP-DOWN CONVERTER TYPICAL APPLICATION CIRCUITS Figure 10—12VIN, 5 V/3 A output Figure 11—12VIN, 3.3 V/3 A output Figure 12—12VIN, 2.5 V/3 A output MP2235S Rev.1.0 4/15/2015 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2015 MPS. All Rights Reserved. 17 MP2235S –3 A, 16 V, 800 kHz SYNCHRONOUS STEP-DOWN CONVERTER Figure 13—12VIN, 1.8 V/3 A output Figure 14—12VIN, 1.2 V/3 A output Figure 15—12VIN, 1 V/3 A output MP2235S Rev.1.0 4/15/2015 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2015 MPS. All Rights Reserved. 18 MP2235S –3 A, 16 V, 800 kHz SYNCHRONOUS STEP-DOWN CONVERTER PACKAGE INFORMATION TSOT23-8 See note 7 EXAMPLE TOP MARK PIN 1 ID IAAAA RECOMMENDED LAND PATTERN TOP VIEW SEATING PLANE SEE DETAIL ''A'' FRONT VIEW SIDE VIEW NOTE: DETAIL ''A'' 1) ALL DIMENSIONS ARE IN MILLIMETERS. 2) PACKAGE LENGTH DOES NOT INCLUDE MOLD FLASH, PROTRUSION OR GATE BURR. 3) PACKAGE WIDTH DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSION. 4) LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.10 MILLIMETERS MAX. 5) JEDEC REFERENCE IS MO-193, VARIATION BA. 6) DRAWING IS NOT TO SCALE. 7) PIN 1 IS LOWER LEFT PIN WHEN READING TOP MARK FROM LEFT TO RIGHT, (SEE EXAMPLE TOP MARK) NOTICE: The information in this document is subject to change without notice. Users should warrant and guarantee that third party Intellectual Property rights are not infringed upon when integrating MPS products into any application. MPS will not assume any legal responsibility for any said applications. MP2235S Rev.1.0 4/15/2015 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2015 MPS. All Rights Reserved. 19