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MP9161A 2A, 6V, 1.5MHz, 17μA IQ, COT Synchronous Step-Down Converter in 8-pin TSOT23 MP9161A Rev. 1.01 www.MonolihicPower.com 1 7/4/2016 MPS Proprietary Information. Patent Protec ted. Unauthorized Photocopy and Duplication Prohibited. © 2016 MPS. All Rights Reserved. The Future of Analog IC Technology
DESCRIPTION
The MP9161A 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 MP9161A is available in a small TSOT23-8 package and requires a minimum number of readily available, standard, external components. The MP9161A is ideal for a wide range of applications including high performance DSPs, FPGAs, PDAs, and portable instruments.
FEATURES
Very Low I Q: 17μA Default 1.5MHz Switching Frequency 1.5% V FB 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 110m Ω 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 MP9161A PGND AGND FB VIN F EN VIN 2.5V to 6V VOUT 1.2V/2A SW 10 F 200k 200k PG EN PG OUT 1 H
MP9161A – 2A, 6V, 1.5MHz SYNCHRONOUS STEP-DOWN CONVERTER MP9161A Rev. 1.01 www.MonolihicPower.com 2 7/4/2016 MPS Proprietary Information. Patent Protec ted. Unauthorized Photocopy and Duplication Prohibited. © 2016 MPS. All Rights Reserved.
ORDERING INFORMATION
Part Number* Package Top Marking MP9161AGJ TSOT23-8 See Below * For Tape & Reel, add suffix –Z (e.g. MP9161AGJ–Z) TOP MARKING AVC: Product code of MP9161AGJ Y: Year code PACKAGE REFERENCE PG VIN SW PGND EN FB AGND OUT TOP VIEW TSOT23-8
MP9161A – 2A, 6V, 1.5MHz SYNCHRONOUS STEP-DOWN CONVERTER MP9161A Rev. 1.01 www.MonolihicPower.com 3 7/4/2016 MPS Proprietary Information. Patent Protec ted. Unauthorized Photocopy and Duplication Prohibited. © 2016 MPS. All Rights Reserved. ABSOLUTE MAXIMUM RATINGS (1) -0.3V (-1.5V for <20ns&-4V for <8ns) to 6.5V (10V for <10ns) Continuous power dissipation (TA = +25°C) (2) Recommended Operating Conditions (3) Operating junction temp. (TJ)... -40°C to +125°C Thermal Resistance (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 T J (MAX), the junction-to- ambient thermal resistance θJA, and the ambient temperature TA. The maximum allowable continuous power dissipation at any ambient temperature is calculated by P D (MAX) = (T J (MAX)-TA)/θJA. Exceeding the maximum allowable powe r 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.
MP9161A – 2A, 6V, 1.5MHz SYNCHRONOUS STEP-DOWN CONVERTER MP9161A Rev. 1.01 www.MonolihicPower.com 4 7/4/2016 MPS Proprietary Information. Patent Protec ted. Unauthorized Photocopy and Duplication Prohibited. © 2016 MPS. All Rights Reserved.
ELECTRICAL CHARACTERISTICS
VIN = 5V, TA = +25C, unless otherwise noted. Parameter Symbol Condition Min Typ Max Units 2.5V ≤ VIN ≤ 6V, TA = 25oC -1.5 0.600 +1.5Feedback voltage V FB V/% Feedback current I FB V FB = 0.6V 10 50 nA PFET switch on resistance R DSON_P 110 m Ω NFET switch on resistance R DSON_N 60 m Ω Switch leakage VEN = 0V, VIN = 6V VSW = 0V and 6V 0 1 μA PFET current limit 2.6 3.2 4.0 A VIN = 5V, VOUT = 1.2V 166 On time T ON VIN = 3.6V, VOUT = 1.2V 220 ns VOUT = 1.2V, TA = 25oC -20 1500 +20 kHz/%Switching frequency F s TA = -40oC to +85oC(6) -25 1500 +25 kHz/% Minimum off time(6) T MIN-OFF 60 ns Soft-start time T SS-ON V OUT from 10% to 90% 0.6 1.15 1.7 ms Power good upper trip threshold PG H FB voltage respect to the regulation +10 % Power good lower trip threshold PG L -10 % Power good delay PG D 50 μs Power good sink current capability V PG-L Sink 1mA 0.4 V Power good logic-high voltage V PG-H V IN = 5V, VFB = 0.6V 4.9 V Power good internal pull-up resistor RPG 550 k Ω Under-voltage lockout threshold— rising 2.15 2.3 2.45 V Under-voltage lockout threshold— hysteresis 260 mV EN input logic-low voltage 0.4 V EN input logic-high voltage 1.2 V VEN = 2V 1.5 μA EN input current VEN = 0V 0 μA Supply current (shutdown) V EN = 0V, VIN = 3V 20 100 nA Supply current (quiescent) VEN = 2V, VFB = 0.63V, VIN = 5V 17 20 μA Thermal shutdown(5) 150 C Thermal hysteresis(5) 30 C NOTES: 5) Guaranteed by design. 6) Guaranteed by characterization test.
MP9161A – 2A, 6V, 1.5MHz SYNCHRONOUS STEP-DOWN CONVERTER MP9161A Rev. 1.01 www.MonolihicPower.com 5 7/4/2016 MPS Proprietary Information. Patent Protec ted. Unauthorized Photocopy and Duplication Prohibited. © 2016 MPS. All Rights Reserved. TYPICAL PERFORMANCE CHARACTERISTICS VIN = 5V, VOUT = 1.2V, L = 1.0µH, TA = +25ºC, unless otherwise noted.
MP9161A – 2A, 6V, 1.5MHz SYNCHRONOUS STEP-DOWN CONVERTER MP9161A Rev. 1.01 www.MonolihicPower.com 6 7/4/2016 MPS Proprietary Information. Patent Protec ted. Unauthorized Photocopy and Duplication Prohibited. © 2016 MPS. All Rights Reserved. TYPICAL PERFORMANCE CHARACTERISTICS (continued) VIN = 5V, VOUT = 1.2V, L = 1.0µH, TA = +25ºC, unless otherwise noted.
MP9161A – 2A, 6V, 1.5MHz SYNCHRONOUS STEP-DOWN CONVERTER MP9161A Rev. 1.01 www.MonolihicPower.com 7 7/4/2016 MPS Proprietary Information. Patent Protec ted. Unauthorized Photocopy and Duplication Prohibited. © 2016 MPS. All Rights Reserved. TYPICAL PERFORMANCE CHARACTERISTICS (continued) VIN = 5V, VOUT = 1.2V, L = 1.0µH, TA = +25ºC, unless otherwise noted.
MP9161A – 2A, 6V, 1.5MHz SYNCHRONOUS STEP-DOWN CONVERTER MP9161A Rev. 1.01 www.MonolihicPower.com 8 7/4/2016 MPS Proprietary Information. Patent Protec ted. Unauthorized Photocopy and Duplication Prohibited. © 2016 MPS. All Rights Reserved. TYPICAL PERFORMANCE CHARACTERISTICS (continued) VIN = 5V, VOUT = 1.2V, L = 1.0µH, TA = +25ºC, unless otherwise noted
MP9161A – 2A, 6V, 1.5MHz SYNCHRONOUS STEP-DOWN CONVERTER MP9161A Rev. 1.01 www.MonolihicPower.com 9 7/4/2016 MPS Proprietary Information. Patent Protec ted. Unauthorized Photocopy and Duplication Prohibited. © 2016 MPS. All Rights Reserved. PIN FUNCTIONS Pin # Name Description 1 PG 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 vo ltage is within ±10% of the regulation level. If FB voltage is out of that regulation range, it is low. 2 VIN Supply voltage. The MP9161A operates from a +2.5V to +6V unregulated input. C1 is needed to prevent large voltage spikes from appearing at the input. 3 SW Switch output. 4 PGND Power ground. 5 OUT Input sense for output voltage. 6 AGND Analogy ground for internal control circuit. 7 FB Feedback. An external resistor divider from the output to AGND (tapped to FB) sets the output voltage. 8 EN On/off control.
MP9161A – 2A, 6V, 1.5MHz SYNCHRONOUS STEP-DOWN CONVERTER MP9161A Rev. 1.01 www.MonolihicPower.com 10 7/4/2016 MPS Proprietary Information. Patent Protec ted. Unauthorized Photocopy and Duplication Prohibited. © 2016 MPS. All Rights Reserved. FUNCTIONAL BLOCK DIAGRAM Main Switch (PCH ) Synchronous Rectifier (N CH ) Constant On -Time Pulse PWM Bias Voltage Reference 0.6V EN FB SW COMP VIN FBCOMP EN Driver PDRV NDRV Soft start PGND AGND OUT PWM COMP COMP 0. 66V 0. 54V PG Hi-Z FB for Fixed Output VIN E.A. Ramp Generator COMP VOUT RST SW Lo-Iq Lo-Iq Lo-Iq Lo-Iq Lo-Iq VTH Figure 1: MP9161A Block Diagram
MP9161A – 2A, 6V, 1.5MHz SYNCHRONOUS STEP-DOWN CONVERTER MP9161A Rev. 1.01 www.MonolihicPower.com 11 7/4/2016 MPS Proprietary Information. Patent Protec ted. Unauthorized Photocopy and Duplication Prohibited. © 2016 MPS. All Rights Reserved. OPERATION The MP9161A 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 MP9161A 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 MP9161A 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): OUT ON IN To prevent inductor current runaway during load transient, the MP9161A fixes the minimum off time at 60ns. However, this minimum off time limit will not affect operation of the MP9161A in steady state. Light-Load Operation In a light-load condition, the MP9161A uses a proprietary control scheme to save power and improve efficiency. The MP9161A turns off the low-side switch when the inductor current starts to reverse. Then the MP9161A 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 MP9161A from entering DCM operation, even with no load. If DCM mode is required, the off time of the LS- FET 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 under- voltage lockout threshold (UVLO), typically 2.3V, the MP9161A is enabled by pulling EN higher than 1.2V. Floating or pulling EN down to ground disables the MP9161A. There is an internal 1M Ω resistor from EN to ground. Soft Start (SS) MP9161A 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 MP9161A has an open drain with a 550k Ω pull- up 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 R dson of less than 400Ω. Current Limit MP9161A has a typical 3.2A current limit for the high-side switch. When the high-side switch hits the current limit, the MP9161A 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 MP9161A 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 MP9161A 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 MP9161A repeats this operation cycle until the short circuit disappears, and the output rises back to regulation level.
MP9161A – 2A, 6V, 1.5MHz SYNCHRONOUS STEP-DOWN CONVERTER MP9161A Rev. 1.01 www.MonolihicPower.com 12 7/4/2016 MPS Proprietary Information. Patent Protec ted. Unauthorized Photocopy and Duplication Prohibited. © 2016 MPS. All Rights Reserved.
APPLICATION INFORMATION
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): out R1R2 V 10.6 (2) The feedback circuit is shown in Figure 2. Vout FB MP9161A Figure 2: Feedback Network Table 1 lists the recommended resistor values for common output voltages. Table 1—Resistor Selection for Common Output Voltages VOUT (V) R1 (k Ω) R2 (k Ω) 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): OUT IN OUT IN L OSC V( V V )L VI f (3) Where ΔIL is the inductor ripple current. Choose the inductor current to be approximately 30% of the maximum load current. The maximum inductor peak current is calculated using Equation (4): III L LOAD)MAX(L (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. 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): IN OUT IN OUTLOAD1C V V1V VII (5) The worse case condition occurs at VIN = 2VOUT, where: II LOAD 1C (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 with Equation (7): LOAD OUT OUT IN INSI N IV VV1 fC 1V V (7)
MP9161A – 2A, 6V, 1.5MHz SYNCHRONOUS STEP-DOWN CONVERTER MP9161A Rev. 1.01 www.MonolihicPower.com 14 7/4/2016 MPS Proprietary Information. Patent Protec ted. Unauthorized Photocopy and Duplication Prohibited. © 2016 MPS. All Rights Reserved. TYPICAL APPLICATION CIRCUITS MP9161A PGND AGND FB VIN F EN VIN 2.5V to 6V VOUT 1.2V/2A SW 10 F 200k 200k PG EN PG OUT 1 H Figure 4: Typical Application Circuit
MP9161A – 2A, 6V, 1.5MHz SYNCHRONOUS STEP-DOWN CONVERTER NOTICE: The information in this document is subject to change wi thout notice. Please contact M PS for current specifications. Users should warrant and guarantee that third party Intellectual Property rights ar e not infringed upon when integrating MPS products into any application. MPS will not assume any legal responsibility for any said applications. MP9161A Rev. 1.01 www.MonolithicPower.com 15 7/4/2016 MPS Proprietary Information. Patent Protec ted. Unauthorized Photocopy and Duplication Prohibited. © 2016 MPS. All Rights Reserved.
PACKAGE INFORMATION
NOTE: 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 ) TOP VIEW RECOMMENDED LAND PATTERN SEATING PLANE SIDE VIEW DETAIL ''A'' SEE DETAIL ''A'' IAAAA PIN 1 ID See note 7 EXAMPLE TOP MARK