MP9159A 1 A, 6 V, 1.5 MHz, Low IQ, COT Synchronous Step-Down Converter in 8-pin TSOT23 The Future of Analog IC Technology DESCRIPTION FEATURES The MP9159A is a monolithic step-down, switch-mode converter with built-in power MOSFETs. It achieves a 1 A continuous output current from a 2.5 V to 6 V input voltage range with excellent load and line regulation. The output voltage can be regulated as low as 0.6 V. 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 MP9159A is available in a small TSOT23-8 package and requires a minimum number of readily available, standard, external components. The MP9159A is ideal for a wide range of applications including high-performance DSPs, FPGAs, PDAs, and portable instruments. Very Low IQ: 17 μA Default 1.5 MHz Switching Frequency 1.5% VFB Accuracy EN and Power Good for Power Sequencing Wide 2.5 V to 6 V Operating Input Range Output Adjustable from 0.6 V Up to 1 A Output Current 100% Duty Cycle in Dropout 120 mΩ and 90 mΩ 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 VOUT 1.2V/1A SW VIN OUT C1 10 F R1 200k MP9159A EN EN PG PG AGND PGND C2 10 F FB R2 200k MP9159A Rev. 1.01 www.MonolithicPower.com 6/30/2016 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2016 MPS. All Rights Reserved. 1 MP9159A – 1 A, 6 V, 1.5 MHz SYNCHRONOUS STEP-DOWN CONVERTER ORDERING INFORMATION Part Number* MP9159AGJ Package TSOT23-8 Top Marking See Below * For Tape & Reel, add suffix –Z (eg. MP9159AGJ–Z) TOP MARKING AVD: Product code of MP9159AGJ 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 MP9159A Rev. 1.01 www.MonolithicPower.com 6/30/2016 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2016 MPS. All Rights Reserved. 2 MP9159A – 1 A, 6 V, 1.5 MHz SYNCHRONOUS STEP-DOWN CONVERTER ABSOLUTE MAXIMUM RATINGS (1) Thermal Resistance Supply voltage (VIN) ................................... 6.5 V VSW ...................................................................... TSOT23-8.............................. 100 ..... 55... C/W -0.3 V (-1.5 V for < 20n s & -4 V for < 8 ns) to 6.5 V (10 V for <10 ns) All other pins ................................-0.3 V to 6.5 V Junction temperature ................................150C Lead temperature .....................................260C (2) Continuous power dissipation (TA = +25°C) ……….….. .............................................. 1.25 W Storage temperature ................ -65C to +150C Recommended Operating Conditions (3) Supply voltage (VIN) .........................2.5 V to 6 V 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. MP9159A Rev. 1.01 www.MonolithicPower.com 6/30/2016 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2016 MPS. All Rights Reserved. 3 MP9159A – 1 A, 6 V, 1.5 MHz SYNCHRONOUS STEP-DOWN CONVERTER ELECTRICAL CHARACTERISTICS VIN = 5 V, TA = +25C, unless otherwise noted. Parameter Symbol Feedback voltage VFB Feedback current PFET switch on resistance NFET switch on resistance IFB Condition 2.5 V ≤ VIN ≤ 6 V, TA=25C TA = -40C to +85C VFB = 0.6 V (6) Max Units -1.5 0.600 +1.5 V/% +2.5 V/% 10 120 90 50 nA mΩ mΩ 0 1 μA -2.5 VEN = 0 V, VIN = 6 V VSW = 0 V and 6 V PFET current limit 2 TON Switching frequency Fs Minimum off time(6) TMIN-OFF Soft-start time Typ RDSON_P RDSON_N Switch leakage On time Min TSS-ON Power good upper trip threshold PGH Power good lower trip threshold VIN = 5 V, VOUT = 1.2 V VIN = 3.6 V, VOUT = 1.2 V VOUT = 1.2 V TA = -40oC to +85oC(6) VOUT from 10% to 90% -20% -25% 0.6 FB voltage respect to the regulation A 166 220 1500 1500 60 1.15 ns +20% +25% kHz/% kHz/% ns 1.7 ms +10 % PGL -10 % Power good delay PGD 50 μs Power good sink current capability VPG-L Sink 1 mA Power good logic high voltage VPG-H VIN = 5 V, VFB = 0.6 V 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 EN input current Supply current (shutdown) Supply current (quiescent) 0.4 4.9 V 550 RPG 2.15 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 = 2 V VEN = 0 V VEN = 0 V, VIN = 3 V VEN = 2 V, VFB = 0.63 V, VIN = 5 V V Thermal shutdown(5) 150 C Thermal hysteresis(5) 30 C NOTES: 5) Guaranteed by design. 6) Guaranteed by characterization test. MP9159A Rev. 1.01 www.MonolithicPower.com 6/30/2016 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2016 MPS. All Rights Reserved. 4 MP9159A – 1 A, 6 V, 1.5 MHz SYNCHRONOUS STEP-DOWN CONVERTER TYPICAL PERFORMANCE CHARACTERISTICS VIN = 5 V, VOUT = 1.2 V, L = 1.0 µH, TA = +25ºC, unless otherwise noted. MP9159A Rev. 1.01 www.MonolithicPower.com 6/30/2016 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2016 MPS. All Rights Reserved. 5 MP9159A – 1 A, 6 V, 1.5 MHz SYNCHRONOUS STEP-DOWN CONVERTER TYPICAL PERFORMANCE CHARACTERISTICS (continued) VIN = 5 V, VOUT = 1.2 V, L = 1.0 µH, TA = +25ºC, unless otherwise noted. MP9159A Rev. 1.01 www.MonolithicPower.com 6/30/2016 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2016 MPS. All Rights Reserved. 6 MP9159A – 1 A, 6 V, 1.5 MHz SYNCHRONOUS STEP-DOWN CONVERTER TYPICAL PERFORMANCE CHARACTERISTICS (continued) VIN = 5 V, VOUT = 1.2 V, L = 1.0 µH, TA = +25ºC, unless otherwise noted. MP9159A Rev. 1.01 www.MonolithicPower.com 6/30/2016 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2016 MPS. All Rights Reserved. 7 MP9159A – 1 A, 6 V, 1.5 MHz SYNCHRONOUS STEP-DOWN CONVERTER TYPICAL PERFORMANCE CHARACTERISTICS (continued) VIN = 5 V, VOUT = 1.2 V, L = 1.0 µH, TA = +25ºC, unless otherwise noted MP9159A Rev. 1.01 www.MonolithicPower.com 6/30/2016 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2016 MPS. All Rights Reserved. 8 MP9159A – 1 A, 6 V, 1.5 MHz SYNCHRONOUS STEP-DOWN CONVERTER PIN FUNCTIONS TSOT23-8 Pin # Name 1 PG 2 VIN 3 4 5 6 SW PGND OUT AGND 7 FB 8 EN Description Power good indicator. The output of PG is an open drain with an internal pull-up resistor 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 this regulation range, it is low. Supply voltage. The MP9159A operates from a +2.5 V to +6 V unregulated input. C1 is required to prevent large voltage spikes from appearing at the input. Switch output. Power ground. Input sense pin for output voltage. Analog ground for internal control circuit. Feedback. An external resistor divider from the output to AGND (tapped to FB) sets the output voltage. On/off control. MP9159A Rev. 1.01 www.MonolithicPower.com 6/30/2016 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2016 MPS. All Rights Reserved. 9 MP9159A – 1 A, 6 V, 1.5 MHz 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 Lo-Iq + COMP 0.54V AGND - PG Figure 1—Functional block diagram MP9159A Rev. 1.01 www.MonolithicPower.com 6/30/2016 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2016 MPS. All Rights Reserved. 10 MP9159A – 1 A, 6 V, 1.5 MHz SYNCHRONOUS STEP-DOWN CONVERTER OPERATION The MP9159A uses constant-on-time (COT) control with input voltage feed forward to stabilize the switching frequency over a full input range. At light load, the MP9159A employs a proprietary control of the low-side switch and the inductor current to eliminate ringing on the switching node and improve efficiency. Constant-On-Time (COT) Control Compare to fixed frequency PWM control, constant-on-time control offers the advantage of a simpler control loop and faster transient response. By using input voltage feed forward, MP9159A maintains a nearly constant switching frequency across the input and output voltage range. The on time of the switching pulse can be estimated using Equation (1): TON V OUT 0.667s VIN (1) To prevent inductor current runaway during load transient, the MP9159A fixes the minimum off time at 60 ns. However, this minimum-off time limit will not affect operation of the MP9159A in steady-state operation. Light-Load Operation In a light-load condition, the MP9159A uses a proprietary control scheme to save power and improve efficiency. It turns off the low-side switch when the inductor current begins to reverse. Then it 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 50 ns. This means the inductor current will still fall after the ZCD is triggered in this delay. 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 phenomena prevents the MP9159A from entering DCM operation even if there is no load. If DCM is required, the off time of the LS-FET in CCM should be longer than 100 ns (2 times the propagation delay). For example, if Vin is 3.6 V and Vo is 3.3 V, the off time in CCM is 55 ns. It is difficult to enter DCM at light load. Using a smaller inductor improves this problem, making it easier to enter DCM. Enable (EN) When the input voltage is greater than the under-voltage lockout threshold (2.3 V, typically), the MP9159A is enabled by pulling EN higher than 1.2 V. Floating EN or pulling EN down to ground disables the MP9159A. There is an internal 1 MΩ resistor from EN to ground. Soft Start (SS) MP9159A 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 period is about 1.15 ms, typically. Power GOOD Indicator (PG) MP9159A has an open drain with a 550 kΩ pullup resistor pin that functions as a power good indicator (PG). When FB is within +/-10% of the regulation voltage (i.e., 0.6 V), 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 400 Ω. Current Limit MP9159A has a minimum 2 A current limit for the high-side switch. When the high-side switch hits the current limit, the MP9159A remains at the hiccup threshold until the current decreases. This prevents the inductor current from continuing to build up, which will result in damage to the components. Short Circuit and Recovery The MP9159A enters short-circuit protection mode when the current limit is reached, and it tries to recover from the short circuit with hiccup mode. During a short-circuit protection, the MP9159A disables the output power stage, discharges the soft-start capacitor, and then automatically tries to soft-start again. If the short-circuit condition still holds after the softstart ends, the MP9159A repeats this operation cycle until the short circuit disappears, and the output rises back to regulation level. MP9159A Rev. 1.01 www.MonolithicPower.com 6/30/2016 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2016 MPS. All Rights Reserved. 11 MP9159A – 1 A, 6 V, 1.5 MHz SYNCHRONOUS STEP-DOWN CONVERTER APPLICATION INFORMATION COMPONENT SELECTION Setting the Output Voltage The external resistor divider sets the output voltage (see Typical Application on page 1). The value of the feedback resistor (R1) cannot be too large or too small, considering the tradeoff between a dynamic circuit and stability in the circuit. Choose R1 around 120 kΩ to 200 kΩ. R2 is then given using Equation (2): R2 R1 Vout 1 0.6 (2) The feedback circuit is highly recommended (see Figure 2). Vout MP9159A R1 FB Figure 2—Feedback network 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, and therefore a capacitor is required to supply the AC current to the stepdown 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 10 µF capacitor is sufficient. For a higher output voltage, a 22 μF capacitor may be needed for a more stable system. I C1 ILOAD (3) VOUT VOUT 1 VIN VIN (5) The worse case condition occurs at VIN = 2VOUT, where: IC1 Selecting the Inductor A 0.68 µH to 2.2 µH inductor is recommended for most applications. For highest efficiency, the inductor DC resistance should be less than 15 mΩ. 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 using Equation (5) and Equation (6): R2 VOUT (V) 1.0 1.2 1.8 2.5 3.3 Choose the inductor current to be approximately 30 percent of the maximum load current. The maximum inductor peak current can be calculated using Equation (4): 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, a small, high-quality ceramic capacitor (e.g., 0.1 μF) 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 using Equation (7): VIN ILOAD V V OUT 1 OUT fS C1 VIN VIN MP9159A Rev. 1.01 www.MonolithicPower.com 6/30/2016 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2016 MPS. All Rights Reserved. (7) 12 MP9159A – 1 A, 6 V, 1.5 MHz 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 using Equation (8): VOUT VOUT V 1 1 OUT RESR fS L1 VIN 8 fS C2 (8) PCB Layout Guidelines Efficient PCB layout is critical for stable operation. For the high-frequency switching converter, a poor layout design can result in poor line or load regulation and stability issues. For best results, refer to Figure 3 and follow the guidelines below: 1. Place the high current paths (GND, VIN, and SW) very close to the device with short, direct, and wide traces. Where L1 is the inductor value and RESR is the equivalent series resistance (ESR) value of the output capacitor. 2. Place the input capacitor as close as possible to VIN and GND. 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 using Equation (9): 4. Keep the switching node (SW) short and away from the feedback network. ΔVOUT (10) The characteristics of the output capacitor affect the stability of the regulation system. GND 8 2 7 3 6 4 5 C2 1 or electrolytic capacitors, the impedance at the For simplification, the be approximated with VOUT V 1 OUT RESR fS L1 VIN R3 R1 ΔVOUT VIN OUT L1 R2 When using tantalum the ESR dominates switching frequency. output ripple can Equation (10): (9) SW R4 C2A V VOUT 1 OUT VIN 8 fS L1 C2 2 3. Place the external feedback resistors next to FB. C1A C1 Figure 3—Recommended PCB layout Design Example Table 2 shows a design example following the application guidelines for the given specifications: Table 2—Design example 5V VIN 1.2 V VOUT 1500 kHz fSW 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. MP9159A Rev. 1.01 www.MonolithicPower.com 6/30/2016 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2016 MPS. All Rights Reserved. 13 MP9159A – 1 A, 6 V, 1.5 MHz SYNCHRONOUS STEP-DOWN CONVERTER TYPICAL APPLICATION CIRCUITS L1 1 H VIN 2.5V to 6V VOUT 1.2V/1A SW VIN OUT C1 10 F C2 10 F R1 200k MP9159A EN EN PG PG AGND PGND FB R2 200k Figure 4—Typical application circuit L1 0.56 H VIN 5V to 6V VIN C1 22 F VOUT 3V/ 1A SW OUT MP9159A EN EN PG PG R1 200k C2 22 F FB AGND PGND R2 49.9k Figure 5—Typical application circuit for higher efficiency at light load MP9159A Rev. 1.01 www.MonolithicPower.com 6/30/2016 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2016 MPS. All Rights Reserved. 14 MP9159A – 1 A, 6 V, 1.5 MHz 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. MP9159A Rev. 1.01 www.MonolithicPower.com 6/30/2016 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2016 MPS. All Rights Reserved. 15