IR3856MTRPBF International Rectifier, IR3856MTRPBF Datasheet
IR3856MTRPBF
Specifications of IR3856MTRPBF
Available stocks
Related parts for IR3856MTRPBF
IR3856MTRPBF Summary of contents
Page 1
SupIRBuck TM INTEGRATED 6A, SYNCHRONOUS BUCK REGULATOR Features • Greater than 95% Maximum Efficiency • Wide Input Voltage Range 1.5V to 21V • Wide Output Voltage Range 0.7V to 0.9*Vin • Continuous 6A Load Capability • Integrated Bootstrap-diode • High ...
Page 2
... POWER QFN 14 Boot 15 Enable 16 Seq 1 Fb Vsns COMP Gnd Rt ORDERING INFORMATION PACKAGE DESIGNATOR M M Rev2 PGnd Vcc 17 9 Sync Gnd 8 PGood OCSet PACKAGE PIN COUNT DESCRIPTION IR3856MTRPbF 15 IR3856MTR1PbF 15 PD-97528 IR3856MPbF and -40 C θ Sync _ FET ) θ Ctrl _ FET ) o θ ...
Page 3
Block Diagram Fig. 2. Simplified block diagram of the IR3856 Rev2.0 PD-97528 IR3856MPbF 3 ...
Page 4
Pin Description Pin Name 1 Fb Inverting input to the error amplifier. This pin is connected directly to the output of the regulator via resistor divider to set the output voltage and provide feedback to the error amplifier. 2 Vsns ...
Page 5
Recommended Operating Conditions Symbol Definition V Input Voltage in V Supply Voltage cc Boot to SW Supply Voltage V Output Voltage o I Output Current o Fs Switching Frequency T Junction Temperature j * Note: SW node should not exceed ...
Page 6
Electrical Specifications (continued) Unless otherwise specified, these specifications apply over 4.5V< V Typical values are specified PARAMETER SYMBOL ERROR AMPLIFIER Input Offset Voltage Input Bias Current Input Bias Current IVseq(E/A) Sink Current Isink(E/A) Source Current ...
Page 7
Electrical Specifications (continued) Unless otherwise specified, these specification apply over 4.5V< V Typical values are specified ARAMETER S YMBOL FAULT PROTECTION OCSET Current OC com p Offset Voltage SS off tim e SS_Hicc up ...
Page 8
Typical Efficiency and Power Loss Curves Vin=12V, Vcc=5V, Io=0.6A- 6A, F The table below shows the inductors used for each of the output voltages in the efficiency measurement. Vo (V) L (uH) 1 0.68 1.2 0.82 1.5 1.0 1.8 1.0 ...
Page 9
Typical Efficiency and Power Loss Curves Vin=5V, Vcc=5V, Io=0.6A- 6A, Fs=600kHz, Room Temperature, No Air Flow The table below shows the inductors used for each of the output voltages in the efficiency measurement. Vo (V) L (uH) 1 0.68 1.2 ...
Page 10
Rdson of MOSFETs Over Temperature at Vcc= -40 -20 0 Rev2 Temperature [ °C] Sync-FET Ctrl-FET PD-97528 IR3856MPbF 100 120 10 ...
Page 11
TYPICAL OPERATING CHARACTERISTICS (-40 Icc(Standby) 290 270 250 230 210 190 170 150 -40 - 100 o Temp[ C] FREQUENCY 550 540 530 520 510 500 490 480 470 460 450 -40 - ...
Page 12
Circuit Description THEORY OF OPERATION Introduction The IR3856 uses a PWM voltage mode control scheme with external compensation to provide good noise immunity and maximum flexibility in selecting inductor values and capacitor types. The switching frequency is programmable from 250kHz ...
Page 13
Figure 3c. shows the recommended startup sequence for sequenced operation of IR3856 with Enable used as logic input. Fig. 3c. Recommended startup sequence, Sequenced operation Pre-Bias Startup IR3856 is able to start up into pre-charged output, which prevents oscillation disturbances ...
Page 14
Operating Frequency The switching frequency can be programmed between 250kHz – 1500kHz by connecting an external resistor from R pin to Gnd. Table 1 t tabulates the oscillator frequency versus R Table 1. Switching Frequency and I External Resistor (R ...
Page 15
Thermal Shutdown Temperature sensing is provided inside IR3856. The trip threshold is typically set to 140 trip threshold is exceeded, thermal shutdown turns off both MOSFETs and discharges the soft start capacitor. Automatic restart is initiated when the sensed temperature ...
Page 16
TIMING DIAGRAM OF PGOOD FUNCTION 2.1V 1.4V 0. Vsns 0.85*Vref(typical), +/-5% for Min/Max 0 PGood 0 100ns(typical) Delay Fig.9a IR3856 Non-Tracking Operation (Seq=Vcc) Rev2.0 1.15*Vref(typical), +/-5% for Min/Max 256/Fs Fig.9b IR3856 Tracking Operation PD-97528 IR3856MPbF PGood window At ...
Page 17
TIMING DIAGRAM OF Over Voltage Protection Fig.10 IR3856 Over Voltage Timing Diagram External Synchronization The IR3856 incorporates an internal circuit which enables synchronization of the internal oscillator (using rising edge external clock. An external resistor from Rt pin ...
Page 18
Minimum on time Considerations The minimum ON time is the shortest amount of time for which the Control FET may be reliably turned on, and this depends on the internal timing delays. For the IR3856, the typical minimum on-time is ...
Page 19
Application Information Design Example: The following example is a typical application for IR3856. The application circuit is shown on page 25 13.2V max 1 ≤ ...
Page 20
C6 remains approximately unchanged and the voltage at the Boot pin becomes: ≅ + − .......... .......... .......... Boot Fig. 13. Bootstrap circuit to generate Vc voltage A bootstrap capacitor of value ...
Page 21
Output Capacitor Selection The voltage ripple and transient requirements determine the output capacitors type and values. The criteria is normally based on the value of the Effective Series Resistance (ESR). However the actual capacitance value and the Equivalent Series Inductance ...
Page 22
Fig. 15. Type II compensation network and its asymptotic gain plot The transfer function ( given by − − ...
Page 23
V OUT E REF Gain(dB) H( Fig.16. Type III Compensation network and its asymptotic gain ...
Page 24
Detailed calculation of compensation Type-III o Θ = Desired Phase Margin 70 − Θ 1 sin = = kHz Θ 1 sin + Θ 1 sin = = F F ...
Page 25
... X7R, 10% Panasonic Thick Film, 0603,1/10W,1% Rohm Thick Film, 0603,1/10W,1% Rohm Thick Film, 0603,1/10W,1% Rohm 0603, 50V, X7R, 10% Panasonic 0603, 16V, X5R, 20% Panasonic SupIRBuck, 6A, PQFN 4x5mm International Rectifier IR3856MPbF PD-97528 IR3856MPbF Part Number EEV-FK1E331P C3216X5R1E106M ECJ-1VB1E104K SPM6550T-1R0M100A ECJ-2FB0J226ML MCR03EZPFX4992 MCR03EZPFX7501 MCR03EZPFX2372 MCR03EZPFX2551 ...
Page 26
TYPICAL OPERATING WAVEFORMS Vin=12.0V, Vcc=5V, Vo=1.8V, Io=0-6A, Room Temperature, No Air Flow Fig. 18: Start Load :Enable out Fig. 20: Start ...
Page 27
TYPICAL OPERATING WAVEFORMS Vin=12V, Vcc=5V, Vo=1.8V, Io=3A- 6A, Room Temperature, No Air Flow Fig. 24: Transient Response step 2.5A/μs Rev2 out 4 out PD-97528 IR3856MPbF 27 ...
Page 28
TYPICAL OPERATING WAVEFORMS Vin=12V, Vcc=5V, Vo=1.8V, Io=6A, Room Temperature, No Air Flow Fig. 25: Bode Plot at 6A load shows a bandwidth of 90kHz and phase margin of 51 degrees Fig. 26: Synchronization to 700kHz external clock signal at 6A ...
Page 29
TYPICAL OPERATING WAVEFORMS Simultaneous Tracking at Power Up and Power Down Vin=12V, Vo=1.8V, Io=6A, Room Temperature, No Air Flow 3.3V R 4.02K 2.55K R Fig. 27: Simultaneous Tracking a 3.3V input at power-up and shut-down Ch : SS(1.8V ...
Page 30
Layout Considerations The layout is very important when designing high frequency switching converters. Layout will affect noise pickup and can cause a good design to perform with less than expected results. Make all the connections for components in the top ...
Page 31
Vin Single point connection between AGND & PGND; It should be close to the SupIRBuck, kept PGnd away from noise sources. Fig. 28b. IRDC3856 demoboard layout considerations – Bottom Layer AGnd Fig. 28c. IRDC3856 demoboard layout considerations – Mid Layer ...
Page 32
PCB Metal and Components Placement Evaluations have shown that the best overall performance is achieved using the substrate/PCB layout as shown in following figures. PQFN devices should be placed to an accuracy of 0.050mm on both X and Y axes. ...
Page 33
Solder Resist IR recommends that the larger Power or Land Area pads are Solder Mask Defined (SMD.) This allows the underlying Copper traces large as possible, which helps in terms of current carrying capability and device cooling ...
Page 34
Stencil Design Stencils for PQFN can be used with thicknesses of 0.100-0.250mm (0.004-0.010"). Stencils thinner than 0.100mm are unsuitable because they deposit insufficient solder paste to make good solder joints with the ground pad; high reductions sometimes create similar problems. ...
Page 35
IR WORLD HEADQUARTERS: This product has been designed and qualified for the Consumer market Rev2.0 233 Kansas St., El Segundo, California 90245, USA Tel: (310) 252-7105 Visit us at www.irf.com for sales contact information Data and specifications subject to change ...