The TPS40074 is a mid voltage, wide input (4

TPS40074

Manufacturer Part NumberTPS40074
DescriptionThe TPS40074 is a mid voltage, wide input (4
ManufacturerTexas Instruments
TPS40074 datasheet
 


Specifications of TPS40074

Switching Frequency(max)(khz)1000Regulated Outputs(#)1
Duty Cycle(max)(%)84Iq(typ)(ma)1.5
Vin(min)(v)4.5Vin(max)(v)28
Iout(max)(a)20Thermal ShutdownYes
Vout(min)(v)0.7Vout(max)(v)23
TopologyBuckPin/package20QFN
Operating Temperature Range(c)-40 to 85  
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MIDRANGE INPUT SYNCHRONOUS BUCK CONTROLLER
FEATURES
Operation Over 4.5-V to 28-V Input Range
Fixed-Frequency Voltage-Mode Controller
Integrated Unity Gain Amplifier for Remote
Output Sensing
Predictive Gate Drive™ Generation II for
Improved Efficiency
<1% Internal 700-mV Reference
Input Voltage Feed Forward Control
Prebiased Output Compatible
Internal Gate Drive Outputs for High-Side and
Synchronous N-Channel MOSFETs
Switching Frequency Programmable to 1 MHz
20-Pin QFN Package
Thermal Shutdown Protection
Software Design Tool and EVM Available
APPLICATIONS
Power Modules
Networking/Telecom
Industrial
Servers
DESCRIPTION
The TPS40074 is a mid voltage, wide input (4.5-V to
28-V), synchronous, step-down controller, offering
design flexibility for a variety of user programmable
functions, including; soft start, UVLO, operating
frequency, voltage feed-forward and high-side FET
sensed short circuit protection.
The TPS40074 incorporates MOSFET gate drivers
for external N-channel high side and synchronous
rectifier (SR) MOSFETs. The gate drive logic
incorporates second generation predictive anti-cross
conduction circuitry to prevent simultaneous high
side and synchronous rectifier conduction, while
minimizing to eliminating current flow in the body
diode of the SR FET. The TPS40074 allows for
starting into pre-biased outputs by not allowing the
synchronous rectifier FET to turn on until the
commanded voltage during soft start is greater than
the existing pre-bias voltage.
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas
Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
Predictive Gate Drive is a trademark of Texas Instruments.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
WITH VOLTAGE FEED-FORWARD
The TPS40074 uses voltage feed-forward control
techniques to provide good line regulation over a
wide input voltage range, and fast response to input
line transients. Voltage feed-forward also provides
nearly constant power stage gain with input variation
to ease loop compensation of wide input range
designs. The externally programmable short circuit
protection provides fault current limiting, as well as
hiccup mode operation for low power dissipation in
the presence of a shorted output. The TPS40074 is
packaged in a 20-pin QFN package for better
thermal
frequencies, as well as reduced footprint.
SIMPLIFIED APPLICATION DIAGRAM
V
OUT
TPS40074
SLUS617B – APRIL 2005 – REVISED OCTOBER 2006
performance
at
higher
voltages
V
+
V
OUT
OUT
(at Load)
(at Load)
1
20
SA−
SA+
TPS 40074
2
SAO
SYNC
19
PowerGood OUT
3
GND
PGD
18
4
SS
LVBP
17
5
FB
RT
16
6
COMP
KFF
15
7
PGND
ILIM
14
8
LDRV
VDD
13
9
DBP
HDRV
12
SW
BOOST
10
11
Copyright © 2005–2006, Texas Instruments Incorporated
and
SYNC IN
V
IN
V
+
OUT
UDG−04075

TPS40074 Summary of contents

  • Page 1

    ... APPLICATIONS Power Modules Networking/Telecom Industrial Servers DESCRIPTION The TPS40074 is a mid voltage, wide input (4.5-V to 28-V), synchronous, step-down controller, offering design flexibility for a variety of user programmable functions, including; soft start, UVLO, operating frequency, voltage feed-forward and high-side FET sensed short circuit protection. The TPS40074 incorporates MOSFET gate drivers for external N-channel high side and synchronous rectifier (SR) MOSFETs ...

  • Page 2

    ... PACKAGE A 40°C to 85°C Plastic QFN (RHL) (1) The TPS40074 is available taped and reeled only. Add an T suffix (i.e. TPS40074RHLT) to the orderable part number for quantities of 250 units per small reel. . (2) Add an R suffix (i.e. TPS40074RHLR) to the orderable part number for quantities of 3,000 units per smalllarge reel. ...

  • Page 3

    ... RHL PACKAGE (BOTTOM VIEW) SYNC 19 2 SAO 20 1 PGD 18 3 GND LVBP KFF COMP ILIM 14 7 PGND 13 8 VDD LDRV HDRV DBP Submit Documentation Feedback TPS40074 SLUS617B – APRIL 2005 – REVISED OCTOBER 2006 3 ...

  • Page 4

    ... TPS40074 SLUS617B – APRIL 2005 – REVISED OCTOBER 2006 ELECTRICAL CHARACTERISTICS T = –40°C to 85° (unless otherwise noted) PARAMETER INPUT SUPPLY V Input voltage range, VIN DD OPERATING CURRENT I Quiescent current DD LVBP V Output voltage LVBP OSCILLATOR/RAMP GENERATOR f Accuracy OSC ...

  • Page 5

    ... 0.7 HDRV - V ) 0.95 HDRV = 0.01A 0.06 = 0.1 A 0.65 = -0.01A 0.65 = -0.1 A 0.875 0.03 0.3 15.2 17.0 rising 6.2 7.2 VDD 1.10 1.55 4.15 4.30 275 365 370 770 630 -9 0.995 1.000 165 15 TPS40074 MAX UNIT V 100 1.0 V 1.35 0.10 V 1.00 1.00 V 1.300 0.05 V 0.5 V 8.2 2.00 V 4.45 mV 550 1.005 MHz °C 5 ...

  • Page 6

    ... TPS40074 SLUS617B – APRIL 2005 – REVISED OCTOBER 2006 TERMINAL I/O NAME NO. The BOOST voltage is 8-V greater than the input voltage. The peak voltage on BOOST is equal to the SW node voltage plus the voltage present at DBP less the bootstrap diode drop. This drop can be 1.4 V for the internal ...

  • Page 7

    ... SW Pulse Control CLK + R RAMP OC CLK OC Predictive Gate Drive CLK PWM Control Logic UVLO FAULT Submit Documentation Feedback TPS40074 SLUS617B – APRIL 2005 – REVISED OCTOBER 2006 9 DBP VDD 14 ILIM SA+ 1 SA− Overcurrent ILIM Comparator OC and Control CLK DBP ...

  • Page 8

    ... SLEW RATE LIMIT ON VDD The regulator that supplies power for the drivers on the TPS40074 requires a limited rising slew rate on VDD for proper operation if the input voltage is above the slew rate is too great, this regulator can over shoot and damage to the part can occur. To ensure that the part operates properly, limit the slew rate to no more than 0.12 V/µ ...

  • Page 9

    ... SR is the maximum allowed slew rate [12 ×10 SETTING THE SWITCHING FREQUENCY (PROGRAMMING THE CLOCK OSCILLATOR) The TPS40074 has independent clock oscillator and PWM ramp generator circuits. The clock oscillator serves as the master clock to the ramp generator circuit. Connecting a single resistor from RT to ground sets the switching frequency of the clock oscillator ...

  • Page 10

    ... TPS40074 SLUS617B – APRIL 2005 – REVISED OCTOBER 2006 APPLICATION INFORMATION (continued) SWITCHING FREQUENCY vs TIMING RESISTANCE 600 500 400 300 200 100 0 0 200 400 f − Switching Frequency − kHz SW Figure 3. PROGRAMMING THE RAMP GENERATOR CIRCUIT AND UVLO FUNCTION The ramp generator circuit provides the actual ramp used by the PWM comparator and provides voltage feed-forward by varying the PWM ramp slope as the line voltage changes ...

  • Page 11

    ... SW UVLOV UVLOV 60 80 100 120 140 R − Feedforward Impedance − k KFF Figure 7. Submit Documentation Feedback TPS40074 SLUS617B – APRIL 2005 – REVISED OCTOBER 2006 UVLOV ON UVLOV OFF 120 150 180 210 240 R − Feedforward Impedance − k KFF Figure 6. ON ...

  • Page 12

    ... TPS40074 SLUS617B – APRIL 2005 – REVISED OCTOBER 2006 APPLICATION INFORMATION (continued) The programmable UVLO circuit incorporates 20% hysteresis from the start voltage to the shutdown voltage. For example, if the startup voltage is programmed the controller starts when V down when V falls below 8 V. The maximum duty cycle begins to decrease as the input voltage rises to twice DD the startup voltage ...

  • Page 13

    ... KFF pin. The TPS40074 holds this pin at a constant 400 mV, so connecting a resistor from KFF to the input power supply causes a current to flow into the KFF pin that is proportional to the input voltage. The slope of the ramp signal to the PWM is therefore proportional to the input voltage ...

  • Page 14

    ... PROGRAMMING SHORT CIRCUIT PROTECTION The TPS40074 uses a two-tier approach to short circuit protection. The first tier is a pulse-by-pulse protection scheme. Short circuit protection is implemented by sensing the voltage drop across the high-side MOSFET while it is turned on. The MOSFET drain to source voltage is compared to the voltage dropped across a resistor (R connected from VDD to the ILIM pin ...

  • Page 15

    ... BLANKING 7 Current Limit Trips (HDRV Cycle Terminated by Current Limit Trip) Figure 11. Typical Fault Protection Waveforms SLUS617B – APRIL 2005 – REVISED OCTOBER 2006 Figure 11 for typical fault protection waveforms. 7 Soft-Start Cycles Submit Documentation Feedback TPS40074 Equation 13) HDRV Clock V ILIM V −V VIN SW SS VDG− ...

  • Page 16

    ... SCP(min) The TPS40074 provides short-circuit protection only. As such recommended that the minimum short circuit protection level be placed at least 20% above the maximum output current required from the converter. The maximum output of the converter should be the steady state maximum output plus any transient specification that may exist ...

  • Page 17

    ... Figure 12. DIFFERENTIAL SENSE AMPLIFIER The TPS40074 has an on board differential amplifier intended for use as a remote sensing amplifier for the output voltage. Use of this amplifier for remote sensing eliminates load regulation issues due to voltage drops that occur between the converter and the actual point of load. The amplifier is powered from the DBP pin and can be used to monitor output voltages with a DBP voltage ...

  • Page 18

    ... In addition to the typical output ripple associated with switching converters, (which can vary from 150 mV) the TPS40074 exhibits a low-frequency ripple from mV. The ripple, a consequence of the charge pump in the driver supply regulator, is well bounded under changes in line, load, and temperature. The ripple frequency does vary with the converter switching frequency and can vary from 10 kHz to 60 kHz ...

  • Page 19

    ... I is the quiescent operating current (neglecting drivers) Q The maximum power capability of the TPS40074 PowerPAD package is dependent on the layout as well as air flow. The thermal impedance from junction to air ambient assuming 2-oz. copper trace and thermal pad with solder and no air flow °C/W ...

  • Page 20

    ... APPLICATION INFORMATION (continued) GROUNDING AND BOARD LAYOUT The TPS40074 provides separate signal ground (GND) and power ground (PGND) pins. Care should be given to proper separation of the circuit grounds. Each ground should consist of a plane to minimize its impedance if possible. The high power noisy circuits such as the output, synchronous rectifier, MOSFET driver decoupling capacitor (DBP), and the input capacitor should be connected to PGND plane ...

  • Page 21

    ... PZ1 PZ2 DBP R R SET2 SET1 C C DBP SS Figure 14. TPS40074 Reference Design Schematic TEST CONDITIONS OUT O(max STEP STEP LOAD 1 20 SA− SA+ TPS40074 R KFF SAO SYNC ...

  • Page 22

    ... SLUS617B – APRIL 2005 – REVISED OCTOBER 2006 3. COMPONENT SELECTION 3. 1 Power Train Components Designers familiar with the buck converter can skip to section 3.2 Component Selection for TPS40074. 3.1.1 Output Inductor The output inductor is one of the most important components to select. It stores the energy necessary to keep the output regulated when the switch MOSFET is turned off ...

  • Page 23

    ... For the GS TPS40074 this Once the above boundary parameters are defined the next step in selecting the switching MOSFET is to select the key performance parameters. Efficiency is the performance characteristic which drives the other selection criteria ...

  • Page 24

    ... However, there are some losses in the body diode. These are minimized by reducing the delay time between the transition from the switching MOSFET turn off to rectifier MOSFET turn on and vice versa. The TPS40074 incorporates TI's proprietary predictive gate drive which helps reduce this delay to between 10 ns and 20 ns. ...

  • Page 25

    ... The ramp is then adjusted to compensate for different input voltages. Is provides the voltage feed forward feature of the TPS40074. The same resistor also sets the under voltage lock out point. The input start voltage should be used to calculate a value for R ...

  • Page 26

    ... ILIM This equation yields a maximum C 3.2.5 Voltage Decoupling Capacitors, C Several pins on the TPS40074 have DC voltages recommended to add small decoupling capacitors to these pins. Below is a list of the recommended values. 26 was chosen. This yields a typical start voltage of 9. This time is given by O can be calculated using ...

  • Page 27

    ... BOOST A capacitor charge pump or boost circuit is required to drive an N-channel MOSFET in the switch location of a buck converter . The TPS40074 contains the elements for this boost circuit. The designer just has to add a capacitor from the switch node of the buck power stage to the BOOST pin of the device. Selection of ...

  • Page 28

    ... The target response is to have the crossover frequency between 1/10 to 1/4 times the switching frequency. To have a phase margin greater than 45° and a gain margin greater than 6 dB. A Type III compensation network, as shown in overall flexibility for compensating the converter. Figure 16. Type III Conpensation with TPS40074 A typical bode plot to this type of compensation network is shown 8377 Hz ...

  • Page 29

    ... PZ2 3559 100 kHz kHz This ensures that the overall system gain falls off quickly co = 200 kHz Submit Documentation Feedback TPS40074 SLUS617B – APRIL 2005 – REVISED OCTOBER 2006 100 Figure 18. (51) (52) (53) (54) (55) (56) (57) ...

  • Page 30

    ... TPS40074 SLUS617B – APRIL 2005 – REVISED OCTOBER 2006 Compensation −10 Response −20 −30 −40 −50 −60 100 Using these values and the equations above the resistors and capacitors around the compensation network can be calculated. 1. Set Calculate R ...

  • Page 31

    ... System Gain 140 ESR = 0.95 m 120 100 100 100 Figure 21 through Figure Submit Documentation Feedback TPS40074 SLUS617B – APRIL 2005 – REVISED OCTOBER 2006 PHASE vs FREQUENCY System Phase ESR = 0 System Phase ESR = 0. 100 Frequency − Hz Figure 20. 23. 31 ...

  • Page 32

    ... F Si7868DP  COEV DXM1306 100 F, TDK, C3225X5R0J107M ( 3)  TDK C4532X5R1C226M ( 2) Figure 21. 400 kHz 1.2 V Converter with Powergood Indication External Logic Supply SA− SA+ TPS40074 2 SAO SYNC 19 3 GND PGD LVBP 17 118 ...

  • Page 33

    ... 88.7 k KFF 15 COMP 1.74 k ILIM PGND LDRV VDD 13 Si7344DP DBP HDRV 12 100 nF SW BOOST 10 11 1.5 100 nF Submit Documentation Feedback TPS40074 SLUS617B – APRIL 2005 – REVISED OCTOBER 2006 VDD 120 F 120 2 180 F 180 F UDG−04110 3 ...

  • Page 34

    ... TPS40074 SLUS617B – APRIL 2005 – REVISED OCTOBER 2006 Figure 23. Sequenced Supplies, Synchronized 180° Out of Phase 34 Submit Documentation Feedback www.ti.com ...

  • Page 35

    ... TPS40074RHLR ACTIVE TPS40074RHLRG4 ACTIVE TPS40074RHLT ACTIVE TPS40074RHLTG4 ACTIVE (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design ...

  • Page 36

    ... TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Type Drawing TPS40074RHLR QFN RHL TPS40074RHLT QFN RHL PACKAGE MATERIALS INFORMATION Pins SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) 20 3000 330.0 12.4 3.8 20 250 180.0 12.4 3.8 Pack Materials-Page 1 1-Dec-2011 Pin1 ...

  • Page 37

    ... Device Package Type TPS40074RHLR QFN TPS40074RHLT QFN PACKAGE MATERIALS INFORMATION Package Drawing Pins SPQ Length (mm) RHL 20 3000 RHL 20 250 Pack Materials-Page 2 1-Dec-2011 Width (mm) Height (mm) 346.0 346.0 29.0 210.0 185.0 35.0 ...

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  • Page 41

    ... Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time and to discontinue any product or service without notice. Customers should obtain the latest relevant information before placing orders and should verify that such information is current and complete. All products are sold subject to TI’ ...