MP2161A 2A, 6V, 1.5MHz, 17μA IQ, COT Synchronous Step-Down Converter in 8-pin TSOT23 The Future of Analog IC Technology DESCRIPTION FEATURES The MP2161A is a monolithic, step-down, switch-mode converter with built-in internal power MOSFETs. It achieves a 2A continuous output current from a 2.5V to 6V input voltage range with excellent load and line regulation. The output voltage is regulated as low as 0.6V. The constant-on-time (COT) control scheme provides fast transient response and eases loop stabilization. Fault condition protection includes cycle-by-cycle current limiting and thermal shutdown. The MP2161A is available in a small TSOT23-8 package and requires a minimum number of readily available, standard, external components. The MP2161A is ideal for a wide range of applications including high performance DSPs, FPGAs, PDAs, and portable instruments. Very Low IQ: 17μA Default 1.5MHz Switching Frequency 1.5% VFB Accuracy EN and Power Good for Power Sequencing Wide 2.5V to 6V Operating Input Range Output Adjustable from 0.6V Up to 2A Output Current 100% Duty Cycle in Dropout 110mΩ and 60mΩ Internal Power MOSFET Switches Cycle-by-Cycle Over-Current Protection Short-Circuit Protection with Hiccup Mode Stable with Low ESR Output Ceramic Capacitors Available in a TSOT23-8 Package APPLICATIONS Wireless/Networking Cards Portable Instruments Battery Powered Devices Low Voltage I/O System Power 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 L1 1 H VIN 2.5V to 6V VIN C1 10 F VOUT 1.2V/ 2A SW OUT MP2161A EN EN PG PG R1 200k C2 10 F FB AGND PGND R2 200k MP2161A Rev. 1.02 www.MonolihicPower.com 6/30/2016 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2016 MPS. All Rights Reserved. 1 MP2161A – 2A, 6V, 1.5MHz SYNCHRONOUS STEP-DOWN CONVERTER ORDERING INFORMATION Part Number* Package Top Marking MP2161AGJ TSOT23-8 See Below * For Tape & Reel, add suffix –Z (e.g. MP2161AGJ–Z) TOP MARKING AKR: Product code of MP2161AGJ Y: Year code PACKAGE REFERENCE TOP VIEW PG 1 8 EN VIN 2 7 FB SW 3 6 AGND PGND 4 5 OUT TSOT23-8 MP2161A Rev. 1.02 www.MonolihicPower.com 6/30/2016 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2016 MPS. All Rights Reserved. 2 MP2161A – 2A, 6V, 1.5MHz SYNCHRONOUS STEP-DOWN CONVERTER ABSOLUTE MAXIMUM RATINGS (1) Thermal Resistance Supply voltage (VIN) .................................... 6.5V VSW ...................................................................... -0.3V (-1.5V for <20ns&-4V for <8ns) to 6.5V (10V for <10ns) All other pins .................................-0.3V to 6.5 V Junction temperature ................................150C Lead temperature .....................................260C (2) Continuous power dissipation (TA = +25°C) ……….….. ............................................... 1.25W Storage temperature ................ -65C to +150C TSOT23-8.............................. 100 ..... 55... C/W Recommended Operating Conditions (3) Supply voltage (VIN) ...........................2.5V to 6V Operating junction temp. (TJ). .. -40°C to +125°C (4) θJA θJC NOTES: 1) Exceeding these ratings may damage the device. 2) The maximum allowable power dissipation is a function of the maximum junction temperature TJ (MAX), the junction-toambient thermal resistance θJA, and the ambient temperature TA. The maximum allowable continuous power dissipation at any ambient temperature is calculated by PD (MAX) = (TJ (MAX)-TA)/θJA. Exceeding the maximum allowable power dissipation will produce an excessive die temperature, causing the regulator to go into thermal shutdown. Internal thermal shutdown circuitry protects the device from permanent damage. 3) The device is not guaranteed to function outside of its operating conditions. 4) Measured on JESD51-7, 4-layer PCB. MP2161A Rev. 1.02 www.MonolihicPower.com 6/30/2016 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2016 MPS. All Rights Reserved. 3 MP2161A – 2A, 6V, 1.5MHz SYNCHRONOUS STEP-DOWN CONVERTER ELECTRICAL CHARACTERISTICS VIN = 5V, TA = +25C, unless otherwise noted. Parameter Feedback voltage Symbol VFB Condition Min Typ Max 2.5V ≤ VIN ≤ 6V, TA = 25oC -1.5 0.600 +1.5 o o TA = -40 C to +85 C Feedback current PFET switch on resistance NFET switch on resistance IFB RDSON_P RDSON_N (6) VFB = 0.6V VEN = 0V, VIN = 6V VSW = 0V and 6V Switch leakage PFET current limit On time 2.6 TON Switching frequency Fs Minimum off time(6) Soft-start time TMIN-OFF TSS-ON Power good upper trip threshold PGH Power good lower trip threshold Power good delay Power good sink current capability Power good logic-high voltage Power good internal pull-up resistor Under-voltage lockout threshold— rising Under-voltage lockout threshold— hysteresis EN input logic-low voltage EN input logic-high voltage PGL PGD VPG-L VPG-H EN input current Supply current (shutdown) Supply current (quiescent) -2.5 VIN = 5V, VOUT = 1.2V VIN = 3.6V, VOUT = 1.2V VOUT = 1.2V, TA = 25oC TA = -40oC to +85oC(6) VOUT from 10% to 90% FB voltage respect to the regulation Sink 1mA VIN = 5V, VFB = 0.6V -20 -25 0.6 10 110 60 50 nA mΩ mΩ 0 1 μA 3.2 166 220 1500 1500 60 1.15 4.0 A ns +20 +25 1.7 % -10 50 % μs V V 550 2.3 kΩ 2.45 260 V mV 0.4 1.5 0 20 100 V V μA μA nA 17 20 μA 1.2 VEN = 2V VEN = 0V VEN = 0V, VIN = 3V VEN = 2V, VFB = 0.63V, VIN = 5V kHz/% kHz/% ns ms +10 0.4 2.15 V/% +2.5 4.9 RPG Units Thermal shutdown(5) 150 C Thermal hysteresis(5) 30 C NOTES: 5) Guaranteed by design. 6) Guaranteed by characterization test. MP2161A Rev. 1.02 www.MonolihicPower.com 6/30/2016 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2016 MPS. All Rights Reserved. 4 MP2161A – 2A, 6V, 1.5MHz SYNCHRONOUS STEP-DOWN CONVERTER TYPICAL PERFORMANCE CHARACTERISTICS VIN = 5V, VOUT = 1.2V, L = 1.0µH, TA = +25ºC, unless otherwise noted. MP2161A Rev. 1.02 www.MonolihicPower.com 6/30/2016 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2016 MPS. All Rights Reserved. 5 MP2161A – 2A, 6V, 1.5MHz SYNCHRONOUS STEP-DOWN CONVERTER TYPICAL PERFORMANCE CHARACTERISTICS (continued) VIN = 5V, VOUT = 1.2V, L = 1.0µH, TA = +25ºC, unless otherwise noted. MP2161A Rev. 1.02 www.MonolihicPower.com 6/30/2016 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2016 MPS. All Rights Reserved. 6 MP2161A – 2A, 6V, 1.5MHz SYNCHRONOUS STEP-DOWN CONVERTER TYPICAL PERFORMANCE CHARACTERISTICS (continued) VIN = 5V, VOUT = 1.2V, L = 1.0µH, TA = +25ºC, unless otherwise noted. MP2161A Rev. 1.02 www.MonolihicPower.com 6/30/2016 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2016 MPS. All Rights Reserved. 7 MP2161A – 2A, 6V, 1.5MHz SYNCHRONOUS STEP-DOWN CONVERTER TYPICAL PERFORMANCE CHARACTERISTICS (continued) VIN = 5V, VOUT = 1.2V, L = 1.0µH, TA = +25ºC, unless otherwise noted MP2161A Rev. 1.02 www.MonolihicPower.com 6/30/2016 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2016 MPS. All Rights Reserved. 8 MP2161A – 2A, 6V, 1.5MHz SYNCHRONOUS STEP-DOWN CONVERTER PIN FUNCTIONS Pin # 1 2 3 4 5 6 7 8 Name Description Power good indicator. The output of PG is an open drain with an internal pull-up resistor PG to VIN. PG is pulled up to VIN when the FB voltage is within ±10% of the regulation level. If FB voltage is out of that regulation range, it is low. Supply voltage. The MP2161A operates from a +2.5V to +6V unregulated input. C1 is VIN needed to prevent large voltage spikes from appearing at the input. SW Switch output. PGND Power ground. OUT Input sense for output voltage. AGND Analogy ground for internal control circuit. Feedback. An external resistor divider from the output to AGND (tapped to FB) sets the FB output voltage. EN On/off control. MP2161A Rev. 1.02 www.MonolihicPower.com 6/30/2016 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2016 MPS. All Rights Reserved. 9 MP2161A – 2A, 6V, 1.5MHz SYNCHRONOUS STEP-DOWN CONVERTER FUNCTIONAL BLOCK DIAGRAM VIN Bias & Voltage Reference EN Soft start + COMP VTH Lo-Iq 0.6V RST + + E.A. - Constant On -Time Pulse PDRV PWM Main Switch (PCH) PWM + Lo-Iq + FB SW EN FBCOMP Driver VOUT Lo-Iq Ramp Generator Synchronous Rectifier ( NCH) SW Lo-Iq Hi-Z NDRV OUT PGND VIN FB for Fixed Output 0.66V + + COMP COMP - - + COMP 0.54V AGND Lo-Iq PG - Figure 1: MP2161A Block Diagram MP2161A Rev. 1.02 www.MonolihicPower.com 6/30/2016 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2016 MPS. All Rights Reserved. 10 MP2161A – 2A, 6V, 1.5MHz SYNCHRONOUS STEP-DOWN CONVERTER OPERATION The MP2161A uses constant-on-time (COT) control with input voltage feed forward to stabilize the switching frequency over the full input range. At light load, the MP2161A employs a proprietary control of the low-side switch and inductor current to eliminate ringing on the switching node and improve efficiency. Constant-On-time (COT) Control Compared to fixed frequency PWM control, constant-on-time (COT) control offers the advantage of a simpler control loop and faster transient response. By using input voltage feed forward, the MP2161A maintains a nearly constant switching frequency across the input and output voltage range. The on time of the switching pulse is estimated with Equation (1): TON V OUT 0.667s VIN (1) To prevent inductor current runaway during load transient, the MP2161A fixes the minimum off time at 60ns. However, this minimum off time limit will not affect operation of the MP2161A in steady state. Light-Load Operation In a light-load condition, the MP2161A uses a proprietary control scheme to save power and improve efficiency. The MP2161A turns off the low-side switch when the inductor current starts to reverse. Then the MP2161A works in discontinuous conduction mode (DCM) operation. There is a zero current cross circuit to detect if the inductor current starts to reverse. Considering the internal circuit propagation time, the typical delay is 50ns. This means that with this delay the inductor current will still fall after the ZCD is triggered. If the inductor current falling slew rate is fast (Vo voltage is high or close to Vin), the low-side MOSFET (LS-FET) is turned off, and the inductor current may be negative. This phenomenon prevents the MP2161A from entering DCM operation, even with no load. If DCM mode is required, the off time of the LSFET in CCM should be longer than 100ns (2 times the propagation delay). For example, if Vin is 3.6V and Vo is 3.3V, the off time in CCM is 55ns. It is difficult to enter DCM at light load. Using a smaller inductor can improve this condition and make it easier to enter DCM. Enable (EN) When the input voltage is greater than the undervoltage lockout threshold (UVLO), typically 2.3V, the MP2161A is enabled by pulling EN higher than 1.2V. Floating or pulling EN down to ground disables the MP2161A. There is an internal 1MΩ resistor from EN to ground. Soft Start (SS) MP2161A has built-in soft start that ramps up the output voltage in a controlled slew rate, avoiding overshoot at start-up. The soft-start time is about 1.15ms typically. Power GOOD Indicator MP2161A has an open drain with a 550kΩ pullup resistor pin for a power good indicator (PG). When FB is within +/-10% of the regulation voltage (e.g., 0.6V), PG is pulled up to VIN by the internal resistor. If the FB voltage is out of the +/10% window, PG is pulled down to ground by an internal MOSFET. The MOSFET has a maximum Rdson of less than 400Ω. Current Limit MP2161A has a typical 3.2A current limit for the high-side switch. When the high-side switch hits the current limit, the MP2161A reaches the hiccup threshold until the current decreases. This prevents the inductor current from continuing to build up, which results in damage to the components. Short Circuit and Recovery The MP2161A enters short-circuit protection mode when the current limit is reached. It tries to recover from the short circuit with hiccup mode. In short-circuit protection, the MP2161A disables the output power stage, discharges a soft-start capacitor, and then automatically tries to soft start again. If the short-circuit condition remains after the soft start ends, the MP2161A repeats this operation cycle until the short circuit disappears, and the output rises back to regulation level. MP2161A Rev. 1.02 www.MonolihicPower.com 6/30/2016 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2016 MPS. All Rights Reserved. 11 MP2161A – 2A, 6V, 1.5MHz SYNCHRONOUS STEP-DOWN CONVERTER APPLICATION INFORMATION COMPONENT SELECTION Setting the Output Voltage An external resistor divider is used to set the output voltage (see Typical Application on page 1). The feedback resistor R1 cannot be too large or too small considering the trade-off between a dynamic circuit and stability in the circuit. Choose R1 around 120kΩ to 200kΩ. R2 is then given using Equation (2): R2 R1 (2) Vout 1 0.6 The feedback circuit is shown in Figure 2. Vout MP2161A R1 FB R2 Table 1 lists the recommended resistor values for common output voltages. Table 1—Resistor Selection for Common Output Voltages R1 (kΩ) 200(1%) 200(1%) 200(1%) 200(1%) 200(1%) R2 (kΩ) 300(1%) 200(1%) 100(1%) 63.2(1%) 44.2(1%) VOUT (VIN VOUT ) VIN IL fOSC Where ΔIL is the inductor ripple current. I L 2 (4) Selecting the Input Capacitor The input current to the step-down converter is discontinuous, therefore a capacitor is required to supply the AC current to the step-down converter while maintaining the DC input voltage. Use low ESR capacitors for the best performance. Ceramic capacitors with X5R or X7R dielectrics are highly recommended because of their low ESR and small temperature coefficients. For most applications, a 10µF capacitor is sufficient. For a higher output voltage, a 47µF capacitor may be needed for a more stable system. I C1 ILOAD VOUT VOUT 1 VIN VIN (5) The worse 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. Selecting the Inductor A 0.68µH to 2.2µH inductor is recommended for most applications. For highest efficiency, the inductor DC resistance should be less than 15mΩ. For most designs, the inductance value can be derived from Equation (3): L1 IL(MAX ) ILOAD Since the input capacitor absorbs the input switching current, it requires an adequate ripple current rating. The RMS current in the input capacitor can be estimated with Equation (5) and Equation (6): Figure 2: Feedback Network VOUT (V) 1.0 1.2 1.8 2.5 3.3 Choose the inductor current to be approximately 30% of the maximum load current. The maximum inductor peak current is calculated using Equation (4): (3) The input capacitor can be electrolytic, tantalum, or ceramic. When using electrolytic or tantalum capacitors, a small, high-quality ceramic capacitor (e.g., 0.1μF) should be placed as close to the IC as possible. When using ceramic capacitors, make sure they have enough capacitance to provide sufficient charge to prevent excessive voltage ripple at the input. The input voltage ripple caused by capacitance can be estimated with Equation (7): VIN ILOAD V V OUT 1 OUT fS C1 VIN VIN MP2161A Rev. 1.02 www.MonolihicPower.com 6/30/2016 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2016 MPS. All Rights Reserved. (7) 12 MP2161A – 2A, 6V, 1.5MHz SYNCHRONOUS STEP-DOWN CONVERTER Selecting the Output Capacitor The output capacitor (C2) is required to maintain the DC output voltage. Ceramic capacitors are recommended. Low ESR capacitors are preferred to keep the output voltage ripple low. The output voltage ripple can be estimated with Equation (8): VOUT VOUT V 1 OUT fS L1 VIN 1 RESR 8 fS C2 (8) Where L1 is the inductor value and RESR is the equivalent series resistance (ESR) value of the output capacitor. When using ceramic capacitors, the impedance at the switching frequency is dominated by the capacitance. The output voltage ripple is caused mainly by the capacitance. For simplification, the output voltage ripple can be estimated with Equation (9): ΔVOUT V VOUT 1 OUT VIN 8 fS L1 C2 2 3. Place the external feedback resistors next to FB. 4. Keep the switching node (SW) short and away from the feedback network. The characteristics of the output capacitor affect the stability of the regulation system. VIN R3 1 GND OUT L1 8 2 7 3 6 4 5 C2 (10) SW R4 C2A RESR 2. Place the input capacitor as close as possible to the VIN and GND pins. (9) or electrolytic capacitors, the impedance at the For simplification, the be approximated with VOUT V 1 OUT fS L1 VIN 1. Place the high current paths (GND, VIN, and SW) very close to the device with short, direct, and wide traces. R1 ΔVOUT Efficient PCB layout of the switching power supplies is critical for proper IC function. A poor layout design can result in poor line or load regulation and stability issues. For best results, please refer to Figure 3 and follow the guidelines below: R2 When using tantalum the ESR dominates switching frequency. output ripple can Equation (10): PCB Layout Guidelines C1A C1 Figure 3: Recommended PCB Layout Design Example Table 2 is a design example following the application guidelines for the specifications: Table 2: Design Example VIN VOUT fSW 5V 1.2V 1500kHz The detailed application schematic is shown in Figure 4. 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. MP2161A Rev. 1.02 www.MonolihicPower.com 6/30/2016 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2016 MPS. All Rights Reserved. 13 MP2161A – 2A, 6V, 1.5MHz SYNCHRONOUS STEP-DOWN CONVERTER TYPICAL APPLICATION CIRCUITS L1 1 H VIN 2.5V to 6V VIN C1 10 F VOUT 1.2V/ 2A SW OUT MP2161A EN EN PG PG R1 200k C2 10 F FB AGND PGND R2 200k Figure 4: Typical Application Circuit MP2161A Rev. 1.02 www.MonolihicPower.com 6/30/2016 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2016 MPS. All Rights Reserved. 14 MP2161A – 2A, 6V, 1.5MHz 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. Please contact MPS for current specifications. 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. MP2161A Rev. 1.02 www.MonolithicPower.com 6/30/2016 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2016 MPS. All Rights Reserved. 15