PAM2316 2.5MHz,Fast Transient 2A Step-Down Converter Features n n n n n n n n n n n n n n n General Description The PAM2316 is a 2A step-down sync converter. The 2.5MHz switching frequency enables the use of small external components. The ultra-small 2mm x 2mm footprint and high efficiency make the PA M 2 3 1 6 a n i d e a l c h o i c e f o r p o r t a b l e applications. The PAM2316 delivers 2 A maximum output current while consuming only 55uA no - load quiescent current. Low R DS(ON) integrated MOSFETs and 100% duty cycle operation make the PAM2316 the ideal choice for high output voltage, high current applications which require a low dropout threshold . The PAM 23 16 p r ov id es ex c el le nt tr an s ie nt r es p o n s e a n d o u tp ut a c c ur a c y a c r o s s th e operating range. T h e PA M 2 3 1 6 m a i n t a i n s h i g h e f f i c i e n c y th r ou g h o u t th e l o a d r a n g e . Th e PA M 2 3 1 6 automatically optimizes efficiency during light l oa d m o de ( P S M) an d m a i nt a i n s c o n s ta n t frequency and low output ripple during PWM mode. Over-temperature and short circuit protection safeguard the PAM2316 and system components from damage. The PAM2316 is available in a Pb-free, ultrasmall, low profile, 8-pin 2mm x 2mm TDFN package. The product is rated over a temperature range of -40°C to 85°C. 2A Maximum Output Current Tiny 1.0uH Chip Inductor Excellent Transient Response Input Voltage: 2.7V to 5.5V Ultra-small, Low Profile 8-pin 2mm x 2mm TDFN Package Fixed or Adjustable Output Voltage - Adjustable Output Voltage: 1.0V to 3.3V High Efficiency with 2.5MHz Switching Frequency 55uA No Load Quiescent Current 100% Duty Cycle Low-Dropout Operation Internal Soft Start Over-Temperature and Current Limit Protection < 1uA Shutdown Current -40°C to 85°C Temperature Range Pb-Free/Halogen Free Package RoHS/REACH Compliant Applications n n n n n n n n Cellular Phone Digital Cameras Hard Disk Drives MP3 Players PDAs and Handheld Computers Portable Media Players USB Devices Wireless Network Cards Typical Application L1 Vin=3.3V C1 10µF C2 1.0µF PVIN SW EN SW VIN FB AGND PGND Vout=1.2V 1.0uH R1 150k C4 100pF C3 10µF R2 150k Vout=0.6* (1+R1/R2) Power Analog Microelectronics, Inc www.poweranalog.com 12/2011 Rev1.1 1 PAM2316 2.5MHz,Fast Transient 2A Step-Down Converter Block Diagram VIN 2.5M OSC SLOPE COMP FREQ SHIFT OSC + IAMP - PVIN FB MAIN SWITCH( PCH) S Q R1 RS LATCH R2 SWITCHING LOGIC AND BLANKING CIRCUIT R Q VIN + EA ANTI SHOOTTHRU SW COMP EN 0.6VREF + IRCMP - SHUTDOWN SYNCHRONOUS RECTIFIER (NCH ) PGND GND Pin Configuration & Marking Information Top View TDFN22-8 PGND 1 8 SW PVIN 2 7 SW VIN 3 6 EN FB 4 5 AGND CH: Product Code of PAM2316 V: Output Voltage Y: Year W: Week Exposed Pad (GND) Pin Description Pin NO. Name Function 1 PGND Main power ground return pin. Connect to the output and input capacitor return. 2 PVIN Input power supply tied to the source of the high side P-channel MOSFET. 3 V IN 4 FB 5 AGND 6 EN 7,8 SW Power supply; supplies power for the internal circuitry. Feedback input pin. Feedback v oltage to internal error amplifier, the threshold voltage is 0.6V. Analog ground. This pin is internally connected to the analog ground of the control circuitry. Enable pin. A logic low disables the converter and it consumes less than 1μA of current. W hen connected high, it resumes normal operation. Switching node. Connect the inductor to this pin. It is internally connected to the drain of both high and low side MOSFETs. Power Analog Microelectronics, Inc www.poweranalog.com 12/2011 Rev1.1 2 PAM2316 2.5MHz,Fast Transient 2A Step-Down Converter Absolute Maximum Ratings These are stress ratings only and functional operation is not implied . Exposure to absolute maximum ratings for prolonged time periods may affect device reliability . All voltages are with respect to ground. Input Voltage..................................-0.3V to 6.5V EN, FB Pin Voltage.............................-0.3V to V IN SW Pi n Voltage.....................-0.3V to ( V IN+0.3V ) Junction Temperature................................150°C Storage Temperature Range........-65°C to 150°C Soldering Temperature......................300°C , 5sec Recommended Operating Conditions Supply Voltage................................2.7V to 5.5V Operation Temperature Range.........-40 °C to 85 °C Junction Temperature Range........-40 °C to 125 °C Thermal Information Parameter Thermal Resistance (Junction to Case) Thermal Resistance (Junc tion to Ambient) Internal Power Diss ipation Package Symbol Maximum TDFN22-8 θJC 23.4 Unit °C/W TDFN22-8 θJ A 70 TDFN22-8 PD 1.4 W Power Analog Microelectronics, Inc www.poweranalog.com 12/2011 Rev1.1 3 PAM2316 2.5MHz,Fast Transient 2A Step-Down Converter Electrical Characteristic TA =25 °C , VIN =3.3V, Vout=1.2V,CIN =10µF, CO =10µF, L=1.0µH, unless otherwise noted. PARAMETER Input Voltage Range UVLO Threshold SYMBOL Test Conditions MIN T YP MAX UNIT S 2.7 3.3 5.5 V V IN Rising 2.6 2.7 V Hysteresis 250 VIN V UVLO V IN Falling 2 Output Voltage Range Vout 1 Output Voltage Accuary Vout Io=0 to 2A Regulated F eedback Voltage V FB No Load PMOS Current Limit ILIM Output Voltage Line Regulation LNR V IN = 3.3V to 4V Output Voltage Load Regulation LDR IO=1mA to 2A Quiescent Current IQ No load Shutdown Current ISD V EN = 0V Oscillator Frequency Drain-Source On-State Res istance SW Leakage Current IDS= 100mA V 1.2 -3.0 0.591 0.60 3.3 V +3.0 % 0.609 V 3.0 A 0.3 %/V -2 55 fOSC RDS(O N) mV 2 % 90 µA 1 µA 2.5 MHz P MOSF ET 105 mΩ N MOSFET 70 mΩ ILSW 1 250 µA Start-up T ime Ts PSM T hreshold ITH EN Threshold High VEH EN Threshold Low V EL EN Leakage Current IEN ±0.01 µA Over T emperature Protection OTP 150 °C OT P Hysteresis OTH 30 °C Vin=3.3V,Vo=1.2V 250 us 450 1.4 mA V 0.4 V Power Analog Microelectronics, Inc www.poweranalog.com 12/2011 Rev1.1 4 PAM2316 2.5MHz,Fast Transient 2A Step-Down Converter Typical Performance Characteristics TA =25 °C , CIN =10μF, CO =10μF,L=1.0µH, unless otherwise noted. Efficiency vs Output Current(Vo=1.2V) Efficiency vs Output Current(Vo=1.5V) 100 100 90 90 80 80 70 70 60 60 50 50 40 40 30 30 Vin=3.3V Vin=4.2V Vin=5V 20 10 Vin=3.3V Vin=4.2V Vin=5V 20 10 0 0 1 10 100 Output Current (mA) 1000 1 10000 Efficiency vs Output Current(Vo=1.8V) 10 100 Output Current (mA) 1000 10000 Efficiency vs Output Current(Vo=2.5V) 100 100 90 90 80 80 70 70 60 60 50 50 40 40 30 30 Vin=3.3V Vin=4.2V Vin=5V 20 10 20 Vin=3.3V Vin=4.2V Vin=5V 10 0 0 1 10 100 1000 10000 1 10 Output Current (mA) 100 1.00 90 0.80 80 0.60 70 0.40 60 0.20 50 0.00 40 -0.20 30 -0.40 Vin=4.2V Vin=5.0V Vin=5.5V 10 1000 10000 Load Regulation Efficiency vs Output Current(Vo=3.3V) 20 100 Output Current (mA) Vo=1.2V L=1.0uH V in= 3. 3V V in= 4. 2V -0.60 -0.80 0 V in= 5. 0V -1.00 1 10 100 Output Current (mA) 1000 10000 1 10 100 1000 10000 Output Current(mA ) Power Analog Microelectronics, Inc www.poweranalog.com 12/2011 Rev1.1 5 PAM2316 2.5MHz,Fast Transient 2A Step-Down Converter Typical Performance Characteristics TA =25 °C , CIN =10μF, CO =10μF,L=1.0µH,unless otherwise noted. Line Regulation Quiescent Current vs Input Voltage 0.5 61 0.4 56 0.3 0.2 0.1 51 0.0 Vo=1.2V L=1.0uH -0.1 46 -0.2 Io= 100mA -0.3 -0.4 Vo=1.2V L=1.0uH 41 Io= 1000mA Io= 2000mA 36 -0.5 2.7 3. 1 3.5 3.9 4.3 Input Voltage(V) 4.7 5.1 2.7 5.5 Rdson vs Input Voltage (Vo=1.2V) 3.1 3.5 3.9 4.3 Input Votage(V) 4.7 5.1 5.5 Start-up Io=2A, Vo=1.2V, Vin=3.3V 120 100 80 60 40 P MOS 20 NMOS 0 2.5 3 3.5 4 4.5 Input V oltage(V) 5 5.5 Load Transient Io=0~2A, Vo=1.2V, Vin=3.3V Load Transient Io=0~2A, Vo=3.3V, Vin=5V Power Analog Microelectronics, Inc www.poweranalog.com 12/2011 Rev1.1 6 PAM2316 2.5MHz,Fast Transient 2A Step-Down Converter Application Information output ripple △ Vout is determined by: The basic PAM2316 application circuit is shown on Page 1. External component selection is determined by the load requirement, selecting L first and then Cin and Cout. △Vout =△IL(ESR+1/8fC OUT) Where f = operating frequency, C OUT=output capacitance and Δ I L = ripple current in the inductor. For a fixed output voltage, the output ripple is highest at maximum input voltage since ΔIL increases with input voltage. Inductor Selection For most applications, the value of the inductor will fall in the range of 0.47µH to 2µH. Its value is chosen based on the desired ripple current. Large value inductors lower ripple current and small value inductors result in higher ripple currents. Higher V IN or Vout also increases the ripple current as shown in equation 2.0A reasonable starting point for setting ripple current is △I L = 800mA (40% of 2A). DIL = V OUT VOUT 1 (f )(L ) VIN 1 Using Ceramic Input and Output Capacitors Higher values, lower cost ceramic capacitors are now becoming available in smaller case sizes. Their high ripple current, high voltage rating and low ESR make them ideal for switching regulator applications. Using ceramic capacitors can achieve very low output ripple and small circuit size. (1) The DC current rating of the inductor should be at least equal to the maximum load current plus half the ripple current to prevent core saturation. Thus, a 2.8A rated inductor should be enough for most applications (2A + 800mA). For better efficiency, choose a low DC-resis tance inductor. When choosing the input and output ceramic capacitors, choose the X5R or X7R dielectric formulations. These dielectrics have the best temperature and voltage charac teristics of all the ceramics for a given value and size. Thermal consideration C IN and C OUT Selection Thermal protection limits power dissipation in the PAM2316. When the junction temperature exceeds 150°C, the OTP (Over Temperature Protection) starts the thermal shutdown and turns the pass transistor off. The pass transistor resumes operation after the junction temperature drops below 120°C. In continuous mode, the source current of the top MOSFET is a square wave of duty cycle Vout/Vin. To prevent large voltage transients, a low ESR input capacitor sized for the maximum RMS current must be used. The maximum RMS capacitor current is given by: 2 VOUT (VIN - VOUT ) CIN required I RMS @ IOMAX VIN 1 For continuous operation, the junction temperature should be maintained below 125°C. The power dissipation is defined as: This formula has a maximum at V IN =2Vout, w h e r e IR MS = IOU T / 2 . T h i s s i m p l e w o r s t - c a s e condition is com monly used for design because even significant deviations do not offer much relief. Note that the capacitor manufacturer's ripple current ratings are often based on 2000 hours of life. This makes it advisable to further derate the capacitor, or choose a capacitor rated at a higher temperature than required. Consult the manufac turer if there is any question. The selection of Cout is driven by the required effective series resistance (ESR). PD =IO 2 VORDSONH + (VIN -VO )R DSONL VIN + (tSW FSIO +IQ )VIN IQ is the step-down converter quiescent current. The term tsw is used to estimate the full load step-down converter switching losses. For the condition where the step-down converter is in dropout at 100% duty cycle, the total device dis sipation reduces to: Typically, once the ESR requirement for Cout has been met, the RMS current rating generally far exceeds the I RIPPLE (P-P) requirement. The 2 PD =IO RDSONH +IQ VIN Since R DS(ON) , quiescent current, and switching Power Analog Microelectronics, Inc www.poweranalog.com 12/2011 Rev1.1 7 PAM2316 2.5MHz,Fast Transient 2A Step-Down Converter losses all vary with input voltage, the total losses should be investigated over the complete input voltage range. The maximum power dissipation de pend s on th e ther ma l r esi sta nc e of IC package, PCB layout, the rate of surrounding airflow and temperature difference between junction and ambient. The maximum power dissipation can be calculated by the following formula: TJ(MAX) -TA PD = θJA enter into low I Q idle state with most of internal blocks disabled. The output voltage will be reduced by loading or leakage current. When the feedback voltage gets lower than the internal reference voltage, the convertor will start a working state again. 100% Duty Cycle Operation As the input voltage approaches the output voltage, the converter turns the P-chan nel transistor continuously on. In this mode the output voltage is equal to the input voltage minus th e voltag e d rop ac ros s the P - c hannel transistor: V OUT = V IN –I LOAD (Rdson + RL ) where Rdson = P-channel switch ON resistance, IL O A D = O ut pu t c u rr e n t, RL = I nd uc t or DC resistance Where TJ(max) is the maximum allowable junction temperature 125°C.T A is the ambient temperature and θJA is the thermal resistance from the junction to the ambient. Based on the standard JEDEC for a two layers thermal test board, the thermal resistance θJA of TDFN2X2 70°C/W, respectively. The maximum power dissipation at T A = 25°C can be calculated by following formula: UVLO and Soft-Start P D=(125°C-25°C)/70°C/W=1.42W The reference and the circuit remain reset until the VIN crosses its UVLO threshold. Setting the Output Voltage The PAM2316 has an internal soft-start circuit that limits the in-rush current during start-up. This prevents possible voltage drops of the input voltage and eliminates the output voltage overshoot. The internal reference is 0.6V (Typical). The output voltage is calculated as below: The output voltage is given by Table 1. R1 VO=0.6×1+ R2 Short Circuit Protection Table 1: Resistor selection for output voltage setting Vo R1 R2 1.2V 150k 150k 1.5V 150k 100k 1.8V 300k 150k 2.5V 380k 120k 3.3V 680k 150k When the converter output is shorted or the device is overloaded,each high-side MOSFET current-limit event (3A typ) turns off the high-side MOSFET and turns on the low-side MOSFET. A internal counter is used to count the each current-limit event. The counter is reset after consecutive high-side MOSFETs turn on without re ac h in g c ur r e nt l i mi t. I f the c ur r en t- l im it condition persists, the counter fills up. The control logic then stops both high-side and lowside MOSFETs and waits for a hiccup period, before attemping a new soft-start sequence. The counter bits is decided by Vfb voltage. If Vfb≤ 0 . 2, the counter is 3-bit counter; if Vfb>0.2 the counter is 6-bit counter. The typical hicuup made duty cycle is 1.7%. The hicuup mode is disable during soft-start time. Pulse Skipping Mode (PSM) Description When load current decreases, the peak switch current in Power-PMOS will be lower than skip current threshold and the device will enter into Pulse Skipping Mode. Thermal Shutdown In this mode, the device has two states, working state and idle state. First, the device enters into wo rk i ng s ta te c on tr ol l ed b y i nte r nal er r or amplifier.When the feedback voltage gets higher than internal reference voltage, the device will When the die temperature exceeds 150°C, a reset occurs and the reset remains until the temperature decrease to 120°C, at which time the circuit can be restarted. Power Analog Microelectronics, Inc www.poweranalog.com 12/2011 Rev1.1 8 PAM2316 2.5MHz,Fast Transient 2A Step-Down Converter PCB Layout Check List When laying out the printed circuit board, the following checklist should be used to ensure proper operation of the PAM2316. Check the following in your layout: 1. The input capacitor should be close to IC as close as possible. 2. Must put a small decoupling capacitor between Vin Pin and AGND Pin. 3. Minimize the switching loop area to avoid excessive switching noise. 4. AGND and PGND should connect at input capacitor GND. 5. For the good thermal dissipation, PAM2316 has a heat dissipate pad in the bottom side, it should be soldered to PCB surface. For the copper area can't be large in the component side, so we can use mu ltiple vias connect to other side of the PCB. Power Analog Microelectronics, Inc www.poweranalog.com 12/2011 Rev1.1 9 PAM2316 2.5MHz,Fast Transient 2A Step-Down Converter Ordering Information PAM 2316 X X X xxx Output Voltage Number of Pins Package Type Pin Configuration Pin Configuration A Type Package Type Number of Pins G: TDFN22-8 C: 8 Output Voltage ADJ: Adjustable(0.6V) P art Numb er Mar kin g Package Type Standard Package PAM2316AGCADJ CHVYW TDF N22-8 3,000 Units/Tape & Reel Power Analog Microelectronics, Inc www.poweranalog.com 12/2011 Rev1.1 10 PAM2316 2.5MHz,Fast Transient 2A Step-Down Converter Outline Dimensions TDFN 2x2 D B INDEX AREA ( D/ 2 xE/ 2) 4 9 TOP VIEW C 8 SEATING PLANE SIDE VIEW 0 .08 C e Nxb Pin #1 ID D BSC 2.00 E BSC 2.00 b D2 D2 MIN 0.18 NOM 0.25 MAX 0.30 MIN 1.55 NOM 1.60 MAX 1.65 MIN 0.85 NOM 0.90 MAX 0.95 MIN 0.20 NOM 0.30 MAX 0.40 BOTTOM VIEW E2 SYMBOL A A1 MIN 0. 70 0. 00 COMMON DIMENSION NOM MAX 0. 75 0. 80 0. 02 0. 05 L Lead Pitch ( e) 0. 50 Summary Table Lead Body Count Size 8 2X2 Pin # 1 ID R0 .20 N 8 Unit: Millimeters Power Analog Microelectronics, Inc www.poweranalog.com 12/2011 Rev1.1 11