The UCC28950 enhanced phase-shifted controller builds upon Texas Instrument’s industry standard UCCx895 phase-shifted controller family with enhancements that offer best in class efficiency in today’s high performance power systems

UCC28950

Manufacturer Part NumberUCC28950
DescriptionThe UCC28950 enhanced phase-shifted controller builds upon Texas Instrument’s industry standard UCCx895 phase-shifted controller family with enhancements that offer best in class efficiency in today’s high performance power systems
ManufacturerTexas Instruments
UCC28950 datasheet
 


Specifications of UCC28950

TopologyFull-BridgeControl MethodCurrent
Duty Cycle(max)(%)97Frequency(max)(khz)1000
Uvlo Thresholds On/off(v)6.75min/6.15minPin/package24TSSOP
Vin(min)(v)8Vin(max)(v)20
Regulated Outputs(#)1Operating Temperature Range(c)-40 to 125
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Green Phase-Shifted Full-Bridge Controller With Synchronous Rectification
FEATURES
1
Enhanced Wide Range Resonant Zero Voltage
Switching (ZVS) Capability
Direct Synchronous Rectifier (SR) Control
Light-Load Efficiency Management Including
– Burst Mode Operation
– Discontinuous Conduction Mode (DCM),
Dynamic SR On/Off Control with
Programmable Threshold
– Programmable Adaptive Delay
Average or Peak Current Mode Control with
Programmable Slope Compensation and
Voltage Mode Control
Naturally Handles Pre-Biased Start Up with
DCM Mode
Closed Loop Soft Start and Enable Function
Programmable Switching Frequency up to 1
MHz with Bi-Directional Synchronization
(+/-3%) Cycle-by-Cycle Current Limit
Protection with Hiccup Mode Support
150-µA Start-Up Current
V
Under Voltage Lockout
DD
Wide Temperature Range -40°C to 125°C
+
CT
V
S
C
REF
-
R1
R3
V
C2
SENSE
R4
R6
C3
ENABLE
R
R
T
V
REF
R
V
REF
Voltage Current
Sense
R7
1
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.
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.
Check for Samples:
UCC28950
APPLICATIONS
Phase-Shifted Full-Bridge Converters
Server, Power Supplies
Datacom, Telecom, and Wireless Base-Station
Power
Industrial Power Systems
High-Density Power Architectures
Solar Inverters, and Electric Vehicles
DESCRIPTION
The UCC28950 enhanced phase-shifted controller
builds upon Texas Instrument’s industry standard
UCCx895
enhancements that offer best in class efficiency in
today’s high performance power systems. The
UCC28950 implements advanced control of the
full-bridge
synchronous rectifier output stage.
The primary-side signals allow programmable delays
to ensure ZVS operation over wide-load current and
input voltage range, while the load current naturally
tunes the secondary-side synchronous rectifiers
switching
efficiency.
UCC28950 Typical Application
UCC28950
R2
1
VREF
GND
24
C
VDD
2
EA+
VDD
23
V
DD
V
3
EA-
OUTA
22
A
C1
R5
4
COMP
OUTB
21
B
A
C
5
SS/EN
OUTC
20
C
SS
R
6
DELAB
OUTD
19
D
AB
V
R
7
DELCD
OUTE
18
E
CD
B
R
8
DELEF
OUTF
17
F
EF
9
TMIN
SYNC
16
SYNC
TMIN
R
A(hi)
10
RT
CS
15
SUM
11
RSUM
ADEL
14
R
E
R
AEF(hi)
DCM(hi)
12
DCM
ADELEF
13
R
A
R
AEF
R
R
CS
DCM
SLUSA16B – MARCH 2010 – REVISED OCTOBER 2011
phase-shifted
controller
along
with
active
control
delays,
maximizing
overall
V
DD
DD
QA
QC
C
V
DD
DD
QB
QD
D
UCC27324
UCC27324
QE
QF
F
V
SENSE
Copyright © 2010–2011, Texas Instruments Incorporated
UCC28950
family
with
of
the
system
V
OUT
+
-

UCC28950 Summary of contents

  • Page 1

    ... Texas Instrument’s industry standard UCCx895 enhancements that offer best in class efficiency in today’s high performance power systems. The UCC28950 implements advanced control of the full-bridge synchronous rectifier output stage. The primary-side signals allow programmable delays to ensure ZVS operation over wide-load current and ...

  • Page 2

    ... SLUSA16B – MARCH 2010 – REVISED OCTOBER 2011 DESCRIPTION (CONT.) The UCC28950 also offers multiple light-load management features including burst mode and dynamic SR on/off control when transitioning in and out of Discontinuous Current Mode (DCM) operation, ensuring ZVS operation is extended down to much lighter loads. ...

  • Page 3

    ... VREF = OSC kΩ between RT and GND; Input pulses 200 kHz 0.5 at SYNC kΩ between RT and 5 V; -40 °C ≤ T 125°C Product Folder Link(s): UCC28950 UCC28950 SLUSA16B – MARCH 2010 – REVISED OCTOBER 2011 TYP MAX UNIT -40 ...

  • Page 4

    ... I = -0.5 mA EAOUT (EA+) - (EA-) = -500 mV 0.5 mA EAOUT Input pulse between CS and GND from zero to 2 2.5 V, VSS = Product Folder Link(s): UCC28950 www.ti.com = 22.6 kΩ 13.3 kΩ, RSUM = 124 100 kHz (F = 200 kHz) SW OSC MIN TYP MAX UNITS 0 ...

  • Page 5

    ... CS = ADEL = ADELEF = 0.2 V, COMP = definitions. ABSET2 CDSET1 CDSET2 , definitions. AFSET2 BESET1 BESET2 Product Folder Link(s): UCC28950 UCC28950 SLUSA16B – MARCH 2010 – REVISED OCTOBER 2011 = 22.6 kΩ 13.3 kΩ, RSUM = 124 100 kHz (F = 200 kHz) SW OSC MIN TYP MAX UNITS ...

  • Page 6

    ... DCM and OUTF pulses CS < DCM threshold R = 88.7 kΩ TMIN C = 100 pF LOAD C = 100 pF LOAD OUT OUT Product Folder Link(s): UCC28950 www.ti.com = 22.6 kΩ 13.3 kΩ, RSUM = 124 100 kHz (F = 200 kHz) SW OSC MIN TYP MAX UNITS 0.37 0.39 0.41 0.364 0.390 ...

  • Page 7

    ... O 0.2-A sink/source primary switching output. O 0.2-A sink/source primary switching output. I Bias supply input. Ground. All signals are referenced to this node. Product Folder Link(s): UCC28950 UCC28950 SLUSA16B – MARCH 2010 – REVISED OCTOBER 2011 FUNCTION AFSET ABSET Submit Documentation Feedback and 7 ...

  • Page 8

    ... A(hi UCC27324 11 RSUM ADEL AEF(hi) 12 DCM ADELEF AEF R DCM Product Folder Link(s): UCC28950 www.ti.com ADEL 14 22 OUTA Programmable 6 DELAB Delay AB 21 OUTB 20 OUTC Programmable 7 DELCD Delay CD 19 OUTD 13 ADELEF 18 OUTE Programmable 8 DELEF Delay EF 17 OUTF V DD ...

  • Page 9

    ... No output delay shown, COMP-to-RAMP offset not included. There is no pulse on OUTE during burst mode at startup. Two falling edge PWM pulses are required before enabling the synchronous rectifier outputs. Copyright © 2010–2011, Texas Instruments Incorporated Figure 1. Figure 2. UCC28950 Timing Diagram NOTE Product Folder Link(s): UCC28950 UCC28950 SLUSA16B – ...

  • Page 10

    ... No PWM pulses shorter than TMIN except during cycle-by-cycle current limit Submit Documentation Feedback TMIN Figure 3. UCC28950 Timing Diagram Product Folder Link(s): UCC28950 www.ti.com VDD failed and VDD_GOOD goes low, Everything is shutdown Copyright © 2010–2011, Texas Instruments Incorporated ...

  • Page 11

    ... DETAILED PIN DESCRIPTION AND PARAMETER SETTINGS Start-Up Protection Logic Before the UCC28950 controller will start up, the following conditions must be met: • VDD voltage exceeds rising UVLO threshold 7.3 V typical. • The 5-V reference voltage is available. • Junction temperature is below the thermal shutdown threshold of 140°C. ...

  • Page 12

    ... Submit Documentation Feedback , connected between SS/EN pin and ground, and SS Equation 1 or Equation 2: SS 20.6 ö ÷ ø is selected ms, and the VNI is 2.5 V, then the SS NOTE Product Folder Link(s): UCC28950 www.ti.com Copyright © 2010–2011, Texas Instruments Incorporated (1) (2) ...

  • Page 13

    ... AHI A from DELAB to GND. The delay T AB connected between DELCD pin and GND sets the delay T CD Product Folder Link(s): UCC28950 UCC28950 SLUSA16B – MARCH 2010 – REVISED OCTOBER 2011 from CS pin to ADEL AHI T ABSET2 T CDSET2 , which is measured ...

  • Page 14

    ... T and T A ABSET CDSET for outputs the same as for A,D. Usually A NOTE and R AB Product Folder Link(s): UCC28950 www.ti.com is replaced numerical A are in ns. These equations are empirical is going to be 90.25 ns. In both ABSET relatively large using equations or plots in are 13 kΩ ...

  • Page 15

    ... T ABSET for TIME DELAY ( kW VOLTAGE 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 CS Voltage - V and T ABSET for Product Folder Link(s): UCC28950 UCC28950 SLUSA16B – MARCH 2010 – REVISED OCTOBER 2011 AH A (Figure 1.0 A 2.0 CDSET and R equal 13 kΩ) ...

  • Page 16

    ... and the delay does not depend on CS voltage where ADELEF AEF NOTE is 13 kΩ kΩ. EF Product Folder Link(s): UCC28950 www.ti.com from CS pin to ADELEF pin AEFHI between outputs OUTA or OUTB going , which is measured 0 when the CS signal is minimized. This ...

  • Page 17

    ... EF EF TIME DELAY ( kW VOLTAGE 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 CS Voltage - V Figure 9. Delay Time T and T AFSET for Product Folder Link(s): UCC28950 UCC28950 SLUSA16B – MARCH 2010 – REVISED OCTOBER 2011 for two different 1.00 A 1.8 equal 13 kΩ 0 ...

  • Page 18

    ... MINIMUM TIME vs RESISTOR SETTING 900 800 700 600 500 400 300 200 100 105 R - Resistor Setting - kW TMIN Equation Product Folder Link(s): UCC28950 www.ti.com 115 125 TMIN Copyright © 2010–2011, Texas Instruments Incorporated (8) (9) ...

  • Page 19

    ... SYNC pins are tied together. The switching frequency of the converter is equal to the frequency of output pulses. The following configured as a master (resistor RT between RT-pin and VREF). On the UCC28950 there is an internal clock oscillator frequency which is twice as that of the controller outputs frequency. ...

  • Page 20

    ... Submit Documentation Feedback Figure 12. Oscillator CLK Ramp VMC Generator RAMP Two Direction Ramp CS_SLOPECOMP Current Sense Summing Mode Select Product Folder Link(s): UCC28950 www.ti.com and 0.85 V PCM Cycle-by-Cycle I LIM + + GND Copyright © 2010–2011, Texas Instruments Incorporated ...

  • Page 21

    ... SLOPE vs RESISTOR 0.50 0.45 0.40 0.35 0.30 0.25 0.20 0.15 0.10 0. 100 120 140 160 R - Resistor - kW sum NOTE is 10 kΩ MΩ. SUM Product Folder Link(s): UCC28950 UCC28950 SLUSA16B – MARCH 2010 – REVISED OCTOBER 2011 13. Because VREF = 5 V, the plots 180 200 Submit Documentation Feedback (13) 21 ...

  • Page 22

    ... Figure 14. DCM Functional Block DUTY CYCLE Moving into vs DCM Mode LOAD CURRENT 0.8 V S(max) 0.6 V S(min) 0.4 MIN 0.2 Area Load Current - A Product Folder Link(s): UCC28950 www.ti.com PWM 2-Cycle Counter 0 = DCM 1 = CCM Copyright © 2010–2011, Texas Instruments Incorporated ...

  • Page 23

    ... DCM must be used in order to prevent reverse current in the output inductor which could cause the synchronous FETS to fail. Copyright © 2010–2011, Texas Instruments Incorporated SLUSA16B – MARCH 2010 – REVISED OCTOBER 2011 Equation 14: Product Folder Link(s): UCC28950 UCC28950 Equation 14 below. When (14) Submit Documentation Feedback 23 ...

  • Page 24

    ... Cycle-by-Cycle I LIM Normal . Operation OFF Time Before Restart 25 mA Fast Pull (-25 x (1-D)+ Switch DS I HCC I = Product Folder Link(s): UCC28950 www.ti.com resistor CS Equation 15 DS Soft Restart = 2 Copyright © 2010–2011, Texas Instruments Incorporated (15) (16) ...

  • Page 25

    ... T CL(on) before the restart, the following ) - 0. voltage is lowered below the UVLO threshold. DD Product Folder Link(s): UCC28950 UCC28950 SLUSA16B – MARCH 2010 – REVISED OCTOBER 2011 time will be 5 ms. Equation 19 or Equation 20 needs to be Submit Documentation Feedback (17) (18) (19) (20) ...

  • Page 26

    ... SLUSA16B – MARCH 2010 – REVISED OCTOBER 2011 Synchronization (SYNC) The UCC28950 allows flexible configuration of converters operating in synchronized mode by connecting all SYNC pins together and by configuration of the controllers as master and/or slaves. The controller configured as Master (resistor between RT and VREF) provides synchronization pulses at the SYNC pin with the frequency equal to 2X the converter frequency F between RT and GND and 825-kΩ ...

  • Page 27

    ... The design is optimized to prevent the latch up of outputs and verified by extensive tests. The UCC28950 has outputs OUTA, OUTB driving the active leg, initiating the duty cycle leg of power MOSFETs in phase-shifted full bridge power stage, and outputs OUTC, OUTD driving the passive leg, completing the duty ...

  • Page 28

    ... TMIN SYNC 16 T(min SUM) 11 RSUM ADEL 14 R DCM(hi) 12 DCM ADELEF DCM Product Folder Link(s): UCC28950 www.ti.com C VDD VDD Power Plane E F SYNC R A(hi AEF(hi) R AEF Copyright © 2010–2011, Texas Instruments Incorporated ...

  • Page 29

    ... SLUSA16B – MARCH 2010 – REVISED OCTOBER 2011 TYPICAL CHARACTERISTICS 640 630 620 610 600 590 580 125 -40 250 200 150 100 50 125 -40 Product Folder Link(s): UCC28950 UCC28950 UVLO HYSTERESIS vs TEMPERATURE UVLO_HYST 25 125 T - Temperature - °C J Figure 24. STARTUP CURRENT vs TEMPERATURE 25 125 T - Temperature - °C J Figure 26. ...

  • Page 30

    ... LOAD 4.993 4.991 4.989 4.987 125 -40 4.985 95.4 95.2 95.0 94.8 94.6 94.4 94.2 94.0 93.8 93.6 125 -40 Copyright © 2010–2011, Texas Instruments Incorporated Product Folder Link(s): UCC28950 www.ti.com = 10 mA) LOAD vs TEMPERATURE REF REF DD 25 125 T - Temperature - °C J Figure 28. MAXIMUM DUTY CYCLE ...

  • Page 31

    ... MAXIMUM SWITCHING FREQUENCY 1079 1059 1039 1019 999 -40 125 VOLTAGE ERROR AMPLIFIER 125 120 115 110 105 100 125 -40 Product Folder Link(s): UCC28950 UCC28950 vs TEMPERATURE 25 125 T - Temperature - °C J Figure 32. (Open Loop Gain) vs TEMPERATURE 25 125 T - Temperature - °C J Figure 34. Submit Documentation Feedback 31 ...

  • Page 32

    ... SS PULL-UP THRESHOLD vs TEMPERATURE 3.71 3.71 3.70 3.70 3.69 - Temperature - °C J Figure 37. 32 Submit Documentation Feedback SHUTDOWN/RESTART/RESET THRESHOLD 0.60 0.55 0.50 0.45 0.40 0.35 0.30 125 -40 4.69 4.69 4.68 4.68 4.68 4.68 4.68 4.67 4.67 4.67 125 -40 Copyright © 2010–2011, Texas Instruments Incorporated Product Folder Link(s): UCC28950 www.ti.com vs TEMPERATURE 25 125 T - Temperature - °C J Figure 36. SS CLAMP VOLTAGE vs TEMPERATURE 25 125 T - Temperature - °C J Figure 38. ...

  • Page 33

    ... SLUSA16B – MARCH 2010 – REVISED OCTOBER 2011 CURRENT SENSE PROPAGATION DELAY 110 107 104 101 98 95 125 -40 OUTPUTS SINK RESISTANCE 17.5 R SINK_OUTE R 15.5 SINK_OUTC R SINK_OUTB 13.5 11.5 9.5 7.5 -40 125 Product Folder Link(s): UCC28950 UCC28950 vs TEMPERATURE 25 125 T - Temperature - °C J Figure 40. vs TEMPERATURE 25 125 T - Temperature - °C J Figure 42. Submit Documentation Feedback 33 ...

  • Page 34

    ... TCDSET2 270 TABSET1 260 250 TAFSET2 240 230 220 125 -40 Copyright © 2010–2011, Texas Instruments Incorporated Product Folder Link(s): UCC28950 www.ti.com vs TEMPERATURE R SRC_OUTE R SRC_OUTD R SRC_OUTB 25 125 T - Temperature - °C J Figure 44. DEAD TIME DELAY vs TEMPERATURE TABSET2 TBESET2 ...

  • Page 35

    ... TYPICAL CHARACTERISTICS (continued) 0.405 0.400 0.395 0.390 0.385 0.380 0.380 0.375 Copyright © 2010–2011, Texas Instruments Incorporated DCM THRESHOLD vs TEMPERATURE - Temperature - °C J Figure 47. Product Folder Link(s): UCC28950 UCC28950 SLUSA16B – MARCH 2010 – REVISED OCTOBER 2011 125 Submit Documentation Feedback 35 ...

  • Page 36

    ... SLUSA16B – MARCH 2010 – REVISED OCTOBER 2011 UCC28950 Application Description The efficiency improvement of phase-shifted full-bridge DC/DC converter with UCC28950 is achieved by using the synchronous rectification technique, control algorithm providing ZVS condition over the entire load current range, accurate adaptive timing of the control signals between primary and secondary FETs and special operating modes at light load for the highest efficiency and power saving ...

  • Page 37

    ... OUTE and OUTF are disabled if V < OUTE and OUTF are disabled if V < Burst Mode at light load with T maintaining ZVS MIN (The time scale is different versus above diagram) Product Folder Link(s): UCC28950 UCC28950 Figure 48. Upper OUT DCM DCM Submit Documentation Feedback . 37 ...

  • Page 38

    ... A type 2 compensation network does not require passive components C compensation is not versatile enough for a phase shifted full bridge. When evaluating the COMP for best results it is recommended to put a 1-kΩ resistor between the scope probe and the COMP pin of the UCC28950 ...

  • Page 39

    ... LIGHT-LOAD POWER LOSSES vs LOAD CURRENT DCM Mode 9 with Diode Rectification 8 7 CCM Mode with Synchronous FETs Burst Mode 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 Load Current - A Product Folder Link(s): UCC28950 UCC28950 SLUSA16B – MARCH 2010 – REVISED OCTOBER 2011 2.0 Submit Documentation Feedback 39 ...

  • Page 40

    ... UCC28950 SLUSA16B – MARCH 2010 – REVISED OCTOBER 2011 Changes from Original (March 2010) to Revision A • Changed UCC28950 Typical Application Diagram ............................................................................................................... • Changed Converter switching frequency from 1400 kHz to 1000 kHz ................................................................................. • Changed Functional Block Diagram ..................................................................................................................................... • Changed Typical Application Diagram .................................................................................................................................. ...

  • Page 41

    ... TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold Customer on an annual basis. OTHER QUALIFIED VERSIONS OF UCC28950 : Automotive: UCC28950-Q1 • ...

  • Page 42

    Automotive - Q100 devices qualified for high-reliability automotive applications targeting zero defects PACKAGE OPTION ADDENDUM Addendum-Page 2 14-Oct-2011 ...

  • Page 43

    ... TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Type Drawing UCC28950PWR TSSOP PW PACKAGE MATERIALS INFORMATION Pins SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) 24 2000 330.0 16.4 6.95 Pack Materials-Page 1 13-Oct-2011 Pin1 (mm) (mm) (mm) (mm) Quadrant 8.3 1.6 8.0 16.0 Q1 ...

  • Page 44

    ... Device Package Type UCC28950PWR TSSOP PACKAGE MATERIALS INFORMATION Package Drawing Pins SPQ Length (mm 2000 Pack Materials-Page 2 13-Oct-2011 Width (mm) Height (mm) 346.0 346.0 33.0 ...

  • Page 45

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  • Page 47

    ... 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’ ...