LTC3719EG Linear Technology, LTC3719EG Datasheet
LTC3719EG
Specifications of LTC3719EG
Available stocks
Related parts for LTC3719EG
LTC3719EG Summary of contents
Page 1
... Overvoltage Soft Latch Eliminates Nuisance Trips Available in 36-Lead Narrow (0.209) SSOP Package U APPLICATIO S Servers and Workstations , LTC and LT are registered trademarks of Linear Technology Corporation. OPTI-LOOP and Burst Mode are registered trademarks of Linear Technology Corporation. AMD Opteron is a trademark of Advanced Micro Devices, Inc. U TYPICAL APPLICATIO 0 ...
Page 2
... IN Measured at FCB pin Measured at V EAIN V Ramping Down 1.2V, Sink/Source 5 A (Note 1.2V, (g • Ext Load) (Note ORDER PART TOP VIEW NUMBER 1 PGOOD 36 2 TG1 35 LTC3719EG 3 SW1 34 4 BOOST1 BG1 31 7 EXTV INTV PGND 28 10 BG2 27 11 ...
Page 3
ELECTRICAL CHARACTERISTICS temperature range, otherwise specifications are at T SYMBOL PARAMETER I Input DC Supply Current Q Normal Mode Shutdown I Soft-Start Charge Current RUN/SS V RUN/SS Pin ON Threshold RUN/SS V RUN/SS Pin Latchoff Arming RUN/SSLO I RUN/SS Discharge ...
Page 4
... Input Resistance IN Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: The LTC3719EG is guaranteed to meet performance specifications from Specifications over the – operating temperature range are assured by design, characterization and correlation with statistical process controls. ...
Page 5
W U TYPICAL PERFOR A CE CHARACTERISTICS Efficiency vs Load Current (3 Operating Modes) (Figure 12) 100 Burst Mode 90 OPERATION 80 70 FORCED 60 CONTINUOUS MODE 50 CONSTANT 40 FREQUENCY 30 (BURST DISABLED ...
Page 6
LTC3719 W U TYPICAL PERFOR A CE CHARACTERISTICS Maximum Current Sense Threshold vs V (Soft-Start) RUN/ 1.55V SENSE(CM (V) RUN/SS 3719 G10 Load Regulation 0.0 FCB ...
Page 7
W U TYPICAL PERFOR A CE CHARACTERISTICS Load Step (Figure 12 12V 1.25V IN OUT V OUT(AC) 50mV/DIV I LOAD 10A/DIV 200 s/DIV 3719 G19 Current Sense Pin Input Current vs Temperature – 1.55V ...
Page 8
LTC3719 CTIO S RUN/SS (Pin 1): Combination of Soft-Start, Run Control Input and Short-Circuit Detection Timer. A capacitor to ground at this pin sets the ramp time to full current output. Forcing this pin below ...
Page 9
CTIO S SW2, SW1 (Pins 25, 34): Switch Node Connections to Inductors. Voltage swing at these pins is from a Schottky diode (external) voltage drop below ground to V BOOST2, BOOST1 (Pins 26, 33): Bootstrapped ...
Page 10
LTC3719 CTIO AL DIAGRA PLLIN PHASE DET f IN 50k PLLFLTR R LP CLK1 C LP OSCILLATOR CLK2 TO SECOND CHANNEL PGOOD – 0.66V + EAIN – + 0.54V – 40k 40k – ...
Page 11
U OPERATIO (Refer to Functional Diagram) Main Control Loop The LTC3719 uses a constant frequency, current mode step-down architecture with the two output stages oper- ating 180 degrees out of phase. During normal operation, each top MOSFET is turned on ...
Page 12
LTC3719 U OPERATIO (Refer to Functional Diagram) Frequency Synchronization The phase-locked loop allows the internal oscillator to be synchronized to an external source via the PLLIN pin. The output of the phase detector at the PLLFLTR pin is also the ...
Page 13
... The inductor value has a direct effect on ripple current. The inductor ripple current I decreases with higher inductance or frequency and increases with higher V PolyPhase is a registered trademark of Linear Technology Corporation. LTC3719 2.5 2.0 1.5 1.0 ...
Page 14
LTC3719 U U APPLICATIO S I FOR ATIO V V OUT OUT • where f is the individual output stage operating frequency 2-phase converter, the net ripple current seen by the ...
Page 15
U U APPLICATIO S I FOR ATIO LTC3719 is operating in continuous mode the duty factors for the top and bottom MOSFETs of each output stage are given by: V OUT Main Switch Duty Cycle V IN Synchronous Switch Duty ...
Page 16
LTC3719 U U APPLICATIO S I FOR ATIO 0.6 0.5 0.4 1-PHASE 2-PHASE 0.3 0.2 0.1 0 0.1 0.2 0.3 0.4 0.5 DUTY FACTOR (V OUT Figure 4. Normalized RMS Input Ripple Current vs Duty Factor for 1 and 2 ...
Page 17
U U APPLICATIO S I FOR ATIO INTV Regulator CC An internal P-channel low dropout regulator produces 5V at the INTV pin from the V supply pin. The INTV CC IN regulator powers the drivers and internal circuitry of the ...
Page 18
LTC3719 U U APPLICATIO S I FOR ATIO Output Voltage The LTC3719 has a true remote voltage sense capablity. The sensing connections should be returned from the load back to the differential amplifier’s inputs through a com- mon, tightly coupled ...
Page 19
U U APPLICATIO S I FOR ATIO Soft-Start/Run Function The RUN/SS pin provides three functions: 1) Run/Shut- down, 2) soft-start and 3) a defeatable short-circuit latchoff timer. Soft-start reduces the input power sources’ surge currents by gradually increasing the controller’s ...
Page 20
LTC3719 U U APPLICATIO S I FOR ATIO condition. When deriving the 5 A current from V the figure, current latchoff is always defeated. The diode connecting this pull-up resistor to INTV eliminates any extra supply current during shutdown while ...
Page 21
U U APPLICATIO S I FOR ATIO The loop filter components ( current pulses from the phase detector and provide a stable input to the voltage controlled oscillator. The filter components C and R determine how fast ...
Page 22
LTC3719 U U APPLICATIO S I FOR ATIO Efficiency Considerations The percent efficiency of a switching regulator is equal to the output power divided by the input power times 100 often useful to analyze individual losses to determine ...
Page 23
U U APPLICATIO S I FOR ATIO Other “hidden” losses such as copper trace and internal battery resistances can account for an additional 5% to 10% efficiency degradation in portable systems very important to include these “system” level ...
Page 24
LTC3719 U U APPLICATIO S I FOR ATIO Design Example As a design example, assume (nominal (max 1.2V 20A and f = 300kHz. OUT MAX A The ...
Page 25
U U APPLICATIO S I FOR ATIO Using Figure 4, the RMS ripple current will be (20A)(0.25 INRMS RMS An input capacitor(s) with a 5A RMS required. The output capacitor ripple current is calculated by using ...
Page 26
LTC3719 U U APPLICATIO S I FOR ATIO The diagram in Figure 9 illustrates all branch currents in a 2-phase switching regulator. It becomes very clear after studying the current waveforms why it is critical to keep the high-switching-current paths ...
Page 27
U U APPLICATIO S I FOR ATIO Simplified Visual Explanation of How a 2-Phase Controller Reduces Both Input and Output RMS Ripple Current A multiphase power supply significantly reduces the amount of ripple current in both the input and output ...
Page 28
LTC3719 U U APPLICATIO S I FOR ATIO Figure 4 illustrates the RMS input current drawn from the input capacitance vs the duty cycle as determined by the ratio of input and output voltage. The peak input RMS current level ...
Page 29
U TYPICAL APPLICATIO LTC3719 sn3719 3719fs 29 ...
Page 30
LTC3719 U TYPICAL APPLICATIO 30 sn3719 3719fs ...
Page 31
... FLASH SHALL NOT EXCEED .254mm (.010") PER SIDE Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen- tation that the interconnection of its circuits as described herein will not infringe on existing patent rights. ...
Page 32
... Dual 2-Phase 550kHz Step-Down Synchronous Controller LTC3729 550kHz PolyPhase Step-Down Synchronous Controller LTC3732 3-Phase Step-Down Synchronous Controller (VRM 9.0/9.1) Adaptive Power and No R are a trademarks of Linear Technology Corporation. SENSE Linear Technology Corporation 32 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 www.linear.com ...