Typical Size
6,4 mm X 9,7 mm
TPS54880
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SLVS450A − OCTOBER 2002 REVISED APRIL 2005
4-V TO 6-V INPUT, 8-A OUTPUT TRACKING SYNCHRONOUS BUCK
PWM SWITCHER WITH INTEGRATED FETs (SWIFT™) FOR SEQUENCING
FEATURES
D Power Up/Down Tracking For Sequencing
D 30-mΩ, 12-A Peak MOSFET Switches for High
D
D
D
D
Efficiency at 8-A Continuous Output Source
or Sink Current
Wide PWM Frequency:
Fixed 350 kHz or Adjustable 280 kHz to
700 kHz
Power Good and Enable
Load Protected by Peak Current Limit and
Thermal Shutdown
Integrated Solution Reduces Board Area and
Component Count
APPLICATIONS
D Low-Voltage, High-Density Distributed Power
Systems
D Point of Load Regulation for High
D
Performance DSPs, FPGAs, ASICs and
Microprocessors Requiring Sequencing
Broadband, Networking and Optical
Communications Infrastructure
DESCRIPTION
As a member of the SWIFT™ family of dc/dc regulators,
the TPS54880 low-input voltage high-output current
synchronous buck PWM converter integrates all
required active components. Using the TRACKIN pin
with other regulators, simultaneous power up and down
are easily implemented. Included on the substrate with
the listed features are a true, high performance, voltage
error amplifier that enables maximum performance and
flexibility in choosing the output filter L and C
components; an under-voltage-lockout circuit to
prevent start-up until the input voltage reaches 3.8 V; an
internally or externally set slow-start circuit to limit
inrush currents; and a power good output useful for
processor/logic reset.
The TPS54880 is available in a thermally enhanced
28-pin TSSOP (PWP) PowerPAD™ package, which
eliminates bulky heatsinks. TI provides evaluation
modules and the SWIFT™ designer software tool to aid
in quickly achieving high-performance power supply
designs to meet aggressive equipment development
cycles.
Input
VIN
PH
TPS54880
BOOT
TRACKIN PGND
VBIAS VSENSE
AGND COMP
Core Supply
STARTUP TIMING
I/O
VI = 5 V
fs = 700 kHz
CORE
PWRGD(I/O)
PWRGD(CORE)
power Good − 5 V/div
I/O Supply
VO − Output Voltage −1 V/div
SIMPLIFIED SCHEMATIC
t − Time − 500 µs/div
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.
PowerPAD and SWIFT are trademarks of Texas Instruments.
PRODUCTION DATA information is current as of publication date. Products
conform to specifications per the terms of Texas Instruments standard warranty.
Production processing does not necessarily include testing of all parameters.
Copyright © 2002 − 2005, Texas Instruments Incorporated
TPS54880
www.ti.com
SLVS450A − OCTOBER 2002 REVISED APRIL 2005
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during
storage or handling to prevent electrostatic damage to the MOS gates.
ORDERING INFORMATION
TA
OUTPUT VOLTAGE
−40°C to 85°C
0.9 V to 3.3 V
PACKAGE
Plastic HTSSOP
PART NUMBER
(PWP)(1)(2)
TPS54880PWP
(1)
For the most current package and ordering information, see the Package Option Addendum at the end of this document, or see the TI website at
www.ti.com.
(2)
The PWP package is also available taped and reeled. Add an R suffix to the device type (i.e., TPS54880PWPR). See the application section of
this data sheet for PowerPAD drawing and layout information.
ABSOLUTE MAXIMUM RATINGS
over operating free-air temperature range unless otherwise noted(1)
TPS54880
Input voltage range,
range VI
VIN, ENA
−0.3 V to 7 V
RT
−0.3 V to 6 V
VSENSE, TRACKIN
−0.3 V to 4V
BOOT
Output voltage range,
range VO
Source current,
current IO
Sink current, IS
Voltage differential
−0.3 V to 17 V
VBIAS, COMP, PWRGD
−0.3 V to 7 V
PH
−0.6 V to 10 V
PH
Internally Limited
COMP, VBIAS
6 mA
PH
12 A
COMP
6 mA
ENA, PWRGD
10 mA
AGND to PGND
±0.3 V
Operating virtual junction temperature range, TJ
−40°C to 125°C
Storage temperature, Tstg
−65°C to 150°C
Lead temperature 1,6 mm (1/16 inch) from case for 10 seconds
(1)
300°C
Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, and
functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not
implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
RECOMMENDED OPERATING CONDITIONS
MIN
Input voltage, VI
Operating junction temperature, TJ
NOM
MAX
UNIT
4
6
V
−40
125
°C
DISSIPATION RATINGS(1)(2)
(1)
PACKAGE
THERMAL IMPEDANCE
JUNCTION-TO-AMBIENT
TA = 25°C
POWER RATING
TA = 70°C
POWER RATING
TA = 85°C
POWER RATING
28 Pin PWP with solder
18.2 °C/W
5.49 W(3)
3.02 W
2.20 W
28 Pin PWP without solder
40.5 °C/W
2.48 W
1.36 W
0.99 W
For more information on the PWP package, refer to TI technical brief, literature number SLMA002.
(2) Test board conditions:
1. 3” x 3”, 4 layers, thickness: 0.062”
2. 1.5 oz. copper traces located on the top of the PCB
3. 1.5 oz. copper ground plane on the bottom of the PCB
4. 0.5 oz. copper ground planes on the 2 internal layers
5. 12 thermal vias (see “Recommended Land Pattern” in applications section of this data sheet)
(3) Maximum power dissipation may be limited by over current protection.
2
TPS54880
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SLVS450A − OCTOBER 2002 REVISED APRIL 2005
ELECTRICAL CHARACTERISTICS
over operating free-air temperature range unless otherwise noted
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
SUPPLY VOLTAGE, VIN
Input voltage range, VIN
I(Q)
Quiescent current
4.0
6.0
fs = 350 kHz, RT open,
PH pin open
11
15.8
fs = 500 kHz, RT = 100 kΩ, PH pin open
16
23.5
1
1.4
3.8
3.85
Shutdown, ENA = 0 V
V
mA
UNDER VOLTAGE LOCK OUT
Start threshold voltage, UVLO
Stop threshold voltage, UVLO
Hysteresis voltage, UVLO
V
3.4
3.5
0.14
0.16
V
2.5
µs
Rising and falling edge deglitch, UVLO(1)
V
BIAS VOLTAGE
Output voltage, VBIAS
I(VBIAS) = 0
2.70
2.80
Output current, VBIAS (2)
2.90
V
100
µA
CUMULATIVE REFERENCE
Vref
Accuracy
0.882
0.891
0.900
V
REGULATION
Line regulation(1)(3)
Load regulation(1)(3)
IL = 3 A, fs = 350 kHz, TJ = 85°C
0.04
IL = 3 A, fs = 550 kHz, TJ = 85°C
0.04
IL = 0 A to 6 A, fs = 350 kHz, TJ = 85°C
0.03
IL = 0 A to 6 A, fs = 550 kHz, TJ = 85°C
0.03
%/V
%/A
OSCILLATOR
Internally set—free running frequency
Externally set
set—free
free running frequency range
RT open
280
350
420
RT = 180 kΩ (1% resistor to AGND)
252
280
308
RT = 100 kΩ (1% resistor to AGND)
460
500
540
RT = 68 kΩ (1% resistor to AGND)
663
700
762
Ramp valley(1)
0.75
Ramp amplitude (peak-to-peak)(1)
Maximum duty cycle
kHz
V
1
Minimum controllable on time(1)
kHz
V
200
ns
90%
(1)
Specified by design
Static resistive loads only
(3) Specified by the circuit used in Figure 9
(2)
3
TPS54880
www.ti.com
SLVS450A − OCTOBER 2002 REVISED APRIL 2005
ELECTRICAL CHARACTERISTICS (continued)
over operating free-air temperature range unless otherwise noted
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
ERROR AMPLIFIER
Error amplifier open loop voltage gain
1 kΩ COMP to AGND(1)
90
110
Error amplifier unity gain bandwidth
Parallel 10 kΩ, 160 pF COMP to AGND(1)
3
5
Error amplifier common mode input voltage range
Powered by internal LDO(1)
0
Input bias current, VSENSE
VSENSE = Vref
Output voltage slew rate (symmetric), COMP
VBIAS
60
1.0
dB
MHz
250
1.4
V
nA
V/µs
PWM COMPARATOR
PWM comparator propagation delay time,
PWM comparator input to PH pin (excluding
deadtime)
10-mV overdrive(1)
70
85
ns
1.20
1.40
V
ENABLE
Enable threshold voltage, ENA
0.82
Enable hysteresis voltage, ENA
Falling edge deglitch,
0.03
ENA(1)
Leakage current, ENA
V
2.5
VI = 5.5 V
µs
1
µA
POWER GOOD
Power good threshold voltage
VSENSE falling
Power good hysteresis voltage(1)
Power good falling edge
deglitch(1)
90
%Vref
3
%Vref
35
Output saturation voltage, PWRGD
I(sink) = 2.5 mA
Leakage current, PWRGD
VI = 5.5 V
0.18
µs
0.3
V
1
µA
CURRENT LIMIT
C
Current
t limit
li it trip
t i point
i t
VI = 4.5 V Output shorted(1)
9
1
Output shorted(1)
10
12
VI = 6 V
A
Current limit leading edge blanking time
100
ns
Current limit total response time
200
ns
THERMAL SHUTDOWN
Thermal shutdown trip point(1)
135
Thermal shutdown hysteresis(1)
150
165
10
°C
°C
OUTPUT POWER MOSFETS
rDS(on)
Power MOSFET switches
VI = 6 V(4)
26
47
VI = 4.5 V(4)
30
60
mΩ
TRACKIN
(1)
Input offset, TRACKIN
VSENSE = TRACKIN = 1.25 V
Input voltage range, TRACKIN
See Note 1
Specified by design
(2) Static resistive loads only
(3) Specified by the circuit used in Figure 9
(4) Matched MOSFETs low-side r
DS(on) production tested, high-side rDS(on) specified by design
4
−1.5
1.5
mV
0
Vref
V
TPS54880
www.ti.com
SLVS450A − OCTOBER 2002 REVISED APRIL 2005
PWP PACKAGE
(TOP VIEW)
AGND
VSENSE
COMP
PWRGD
BOOT
PH
PH
PH
PH
PH
PH
PH
PH
PH
1
2
3
4
5
6
7
8
9
10
11
12
13
14
28
27
26
25
24
23
THERMAL 22
PAD
21
20
19
18
17
16
15
RT
ENA
TRACKIN
VBIAS
VIN
VIN
VIN
VIN
VIN
PGND
PGND
PGND
PGND
PGND
TERMINAL FUNCTIONS
TERMINAL
NAME
NO.
DESCRIPTION
AGND
1
Analog ground. Return for compensation network/output divider, slow-start capacitor, VBIAS capacitor, RT resistor.
Connect PowerPAD to AGND.
BOOT
5
Bootstrap output. 0.022-µF to 0.1-µF low-ESR capacitor connected from BOOT to PH generates floating drive for the
high-side FET driver.
COMP
3
Error amplifier output. Connect frequency compensation network from COMP to VSENSE
ENA
27
Enable input. Logic high enables oscillator, PWM control and MOSFET driver circuits. Logic low disables operation and
places device in low quiescent current state.
PGND
15−19
Power ground. High current return for the low-side driver and power MOSFET. Connect PGND with large copper areas
to the input and output supply returns, and negative terminals of the input and output capacitors. A single point connection
to AGND is recommended.
PH
6−14
Phase output. Junction of the internal high-side and low-side power MOSFETs, and output inductor.
PWRGD
4
Power good open drain output. High when VSENSE ≥ 90% Vref, otherwise PWRGD is low.
RT
28
Frequency setting resistor input. Connect a resistor from RT to AGND to set the switching frequency.
TRACKIN
26
External reference input. High impedance input to internal reference/multiplexer and error amplifier circuits.
VBIAS
25
Internal bias regulator output. Supplies regulated voltage to internal circuitry. Bypass VBIAS pin to AGND pin with a high
quality, low-ESR 0.1-µF to 1.0-µF ceramic capacitor.
20−24
Input supply for the power MOSFET switches and internal bias regulator. Bypass VIN pins to PGND pins close to device
package with a high quality, low-ESR 10-µF ceramic capacitor.
VIN
VSENSE
2
Error amplifier inverting input. Connect to output voltage through compensation network/output divider.
5
TPS54880
www.ti.com
SLVS450A − OCTOBER 2002 REVISED APRIL 2005
INTERNAL BLOCK DIAGRAM
VBIAS
AGND
Enable
Comparator
ENA
1.2 V
Hysteresis: 0.03 V
Falling
Edge
Deglitch
2.5 µs
VIN UVLO
Comparator
VIN
3.8 V
Hysteresis: 0.16 V
I/O
VIN
ILIM
Comparator
Thermal
Shutdown
150°C
Falling
and
Rising
Edge
Deglitch
100 ns
BOOT
sense Fet
30 mΩ
2.5 µs
SHUTDOWN
PH
Multiplexer
+
−
R Q
Error
Amplifier
Reference
S
PWM
Comparator
25 ns Adaptive
Dead Time
VIN
30 mΩ
PGND
Powergood
Comparator
VSENSE
0.90 Vref
TPS54880
Hysteresis: 0.03 Vref
VSENSE
COMP
RELATED DC/DC PRODUCTS
D TPS56300—dc/dc controller
D PT6600 series—6-A plugin modules
RT
SHUTDOWN
LOUT
CO
Adaptive Dead-Time
and
Control Logic
OSC
6
VIN
Leading
Edge
Blanking
SS_DIS
TRACKIN
REG
VBIAS
SHUTDOWN
Falling
Edge
Deglitch
35 µs
PWRGD
Core
TPS54880
www.ti.com
SLVS450A − OCTOBER 2002 REVISED APRIL 2005
TYPICAL CHARACTERISTICS
INTERNALLY SET
OSCILLATOR FREQUENCY
vs
JUNCTION TEMPERATURE
VIN = 5 V
50
40
IO = 6 A
30
20
10
0
−40
0
25
85
TJ − Junction Temperature − °C
125
750
650
550
450
350
250
−40
0
25
85
125
800
700
RT = 68 k
600
500
RT = 100 k
400
300
RT = 180 k
200
−40
0
DEVICE POWER LOSSES AT TJ = 125°C
vs
LOAD CURRENT
0.895
0.895
TJ = 125°C
fs = 700 kHz
0.889
0.887
4
VO − Output Voltage Regulation − V
Device Power Losses − W
0.891
125
OUTPUT VOLTAGE REGULATION
vs
INPUT VOLTAGE
5
4.5
0.893
85
Figure 3
Figure 2
VOLTAGE REFERENCE
vs
JUNCTION TEMPERATURE
25
TJ − Junction Temperature − °C
TJ − Junction Temperature − °C
Figure 1
3.5
3
2.5
2
1.5
VI = 5 V
1
TA = 85°C,
IO = 3 A
0.893
0.891
fs = 550 kHz
0.889
0.887
0.5
0.885
0
25
85
TJ − Junction Temperature − °C
0
125
0.885
0
1
2
3
4
5
6
7
3
8
IL − Load Current − A
Figure 4
Figure 5
3.5
4
4.5
5
VI − Input Voltage − V
5.5
6
Figure 6
ERROR AMPLIFIER
OPEN LOOP RESPONSE
140
RL = 10 kΩ,
CL = 160 pF,
TA = 25°C
120
100
−20
−40
−60
80
Phase
−80
−100
60
−120
40
Gain
20
−140
−160
0
−20
0
Phase − Degrees
−40
Gain − dB
V ref − Voltage Reference − V
EXTERNALLY SET
OSCILLATOR FREQUENCY
vs
JUNCTION TEMPERATURE
f − Externally Set Oscillator Frequency − kHz
60
f − Internally Set Oscillator Frequency − kHz
Drain Source On-State Reststance − m Ω
DRAIN-SOURCE
ON-STATE RESISTANCE
vs
JUNCTION TEMPERATURE
−180
1
10
100
1k
−200
10 k 100 k 1 M 10 M
f − Frequency − Hz
Figure 7
7
TPS54880
www.ti.com
SLVS450A − OCTOBER 2002 REVISED APRIL 2005
APPLICATION INFORMATION
Figure 8 shows the schematic diagram for a typical
TPS54880 application. The TPS54880 (U1) can provide
greater than 8 A of output current at a nominal output
voltage of 1.8 V. For proper thermal performance, the
exposed thermal PowerPAD underneath the integrated
circuit package must be soldered to the printed-circuit
board. To provide power up tracking, the enable of the I/O
supply should be used. If the I/O enable is not used to
power up, then devices with similar undervoltage lockout
thresholds need to be implemented to ensure power up
tracking. To ensure power down tracking, the enable pin
should be used.
TPS54810
I/O Power Supply
R2
R4
10 kΩ
71.5 kΩ
R6
9.76 kΩ
C2
1 µF
VIN
C6
10 µF
C7
10 µF
28
27
VOUT_I/O
R1
10 kΩ
U1
RT
AGND
ENA
VSENSE
TRACKIN COMP
VBIAS PWRGD
BOOT
VIN
VIN
PH
26
25
24
23
22
VIN
21
VIN
20 VIN
19
PGND
18
PGND
17 PGND
16 PGND
15 PGND
PwrPad
1
2
3
4
5
6
7
R3
R5
C1
470 pF
C4
C5
PH
8
PH
9
PH
10
PH
11
PH
12
PH
13
PH
14
PH
10 kΩ
C3
301 Ω 470 pF
R8
12 pF
0.047 µF
10 kΩ
R7
9.76 kΩ
L1
R9
0.65 µH
2.2 Ω
VOUT_CORE
C8
22 µF
C9
22 µF
C10
22 µF
C11
3300 pF
Analog and Power Grounds are Tied at
the Power Pad Under the Package of IC
Figure 8. Application Circuit
COMPONENT SELECTION
The values for the components used in this design
example were selected for low output ripple voltage and
small PCB area. Additional design information is available
at www.ti.com.
INPUT FILTER
The input voltage is a nominal 5 Vdc. The input filter C6 is
a 10-µF ceramic capacitor (Taiyo Yuden). C7 also a 10-µF
ceramic capacitor (Taiyo Yuden) provides high frequency
decoupling of the TPS54880 from the input supply and
must be located as close as possible to the device. Ripple
current is carried in both C6 and C7, and the return path to
PGND must avoid the current circulating in the output
capacitors C8, C9, and C10.
FEEDBACK CIRCUIT
The values for these components have been selected to
provide low output ripple voltage. The resistor divider
network of R3 and R8 sets the output voltage for the circuit
8
at 1.8 V. R3, along with R7, R5, C1, C3, and C4 form the
loop compensation network for the circuit. For this design,
a Type 3 topology is used.
OPERATING FREQUENCY
In the application circuit, the 350 kHz operation is selected
by leaving RT open. Connecting a 180 kΩ to 68 kΩ resistor
between RT (pin 28) and analog ground can be used to set
the switching frequency to 280 kHz to 700 kHz. To
calculate the RT resistor, use the equation below:
R+
500 kHz
Switching Frequency
100 [kW]
(1)
OUTPUT FILTER
The output filter is composed of a 0.65-µH inductor and 3
x 22-µF capacitor. The inductor is a low dc resistance
(0.017 Ω) type, Pulse Engineering PA0227. The
capacitors used are 22-µF, 6.3 V ceramic types with X5R
dielectric. The feedback loop is compensated so that the
unity gain frequency is approximately 75 kHz.
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TPS54880
SLVS450A − OCTOBER 2002 REVISED APRIL 2005
PCB LAYOUT
Figure 9 shows a generalized PCB layout guide for the
TPS54880.
The VIN pins should be connected together on the printed
circuit board (PCB) and bypassed with a low ESR ceramic
bypass capacitor. Care should be taken to minimize the
loop area formed by the bypass capacitor connections, the
VIN pins, and the TPS54880 ground pins. The minimum
recommended bypass capacitance is 10-µF ceramic with
a X5R or X7R dielectric and the optimum placement is
closest to the VIN pins and the PGND pins.
The TPS54880 has two internal grounds (analog and
power). Inside the TPS54880, the analog ground ties to all
of the noise sensitive signals, while the power ground ties
to the noisier power signals. Noise injected between the
two grounds can degrade the performance of the
TPS54880, particularly at higher output currents. Ground
noise on an analog ground plane can also cause problems
with some of the control and bias signals. For these
reasons, separate analog and power ground traces are
recommended. There should be an area of ground one the
top layer directly under the IC, with an exposed area for
connection to the PowerPAD. Use vias to connect this
ground area to any internal ground planes. Use additional
vias at the ground side of the input and output filter
capacitors as well. The AGND and PGND pins should be
tied to the PCB ground by connecting them to the ground
area under the device as shown. The only components
that should tie directly to the power ground plane are the
input capacitors, the output capacitors, the input voltage
decoupling capacitor, and the PGND pins of the
TPS54880. Use a separate wide trace for the analog
ground signal path. This analog ground should be used for
the voltage set point divider, timing resistor RT and bias
capacitor grounds. Connect this trace directly to AGND
(pin 1).
The PH pins should be tied together and routed to the
output inductor. Since the PH connection is the switching
node, inductor should be located very close to the PH pins
and the area of the PCB conductor minimized to prevent
excessive capacitive coupling.
Connect the boot capacitor between the phase node and
the BOOT pin as shown. Keep the boot capacitor close to
the IC and minimize the conductor trace lengths.
Connect the output filter capacitor(s) as shown between
the VOUT trace and PGND. It is important to keep the loop
formed by the PH pins, Lout, Cout and PGND as small as
practical.
Place the compensation components from the VOUT trace
to the VSENSE and COMP pins. Do not place these
components too close to the PH trace. Do to the size of the
IC package and the device pinout, they will have to be
routed somewhat close, but maintain as much separation
as possible while still keeping the layout compact.
Connect the bias capacitor from the VBIAS pin to analog
ground using the isolated analog ground trace. If an RT
resistor is used, connect it to this trace as well.
9
TPS54880
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SLVS450A − OCTOBER 2002 REVISED APRIL 2005
ANALOG GROUND TRACE
AGND
RT
COMPENSATION
NETWORK
TRACKING VOLTAGE
ENA
VSENSE
COMP
TRACKIN
BIAS CAPACITOR
PWRGD
BOOT
CAPACITOR
BOOT
PH
VOUT
PH
OUTPUT INDUCTOR
OUTPUT
FILTER
CAPACITOR
VBIAS
VIN
EXPOSED
POWERPAD
AREA
VIN
PH
VIN
PH
VIN
PH
VIN
PH
PGND
PH
PGND
PH
PGND
PH
PGND
PH
PGND
VIN
INPUT
BYPASS
CAPACITOR
INPUT
BULK
FILTER
TOPSIDE GROUND AREA
VIA to Ground Plane
Figure 9. TPS54880 PCB Layout
10
RESISTOR DIVIDER
NETWORK
TPS54880
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SLVS450A − OCTOBER 2002 REVISED APRIL 2005
LAYOUT CONSIDERATIONS FOR THERMAL
PERFORMANCE
For operation at full rated load current, the analog ground
plane must provide an adequate heat dissipating area. A
3-inch by 3-inch plane of 1 ounce copper is recommended,
though not mandatory, depending on ambient temperature
and airflow. Most applications have larger areas of internal
ground plane available, and the PowerPAD must be
connected to the largest area available. Additional areas
on the top or bottom layers also help dissipate heat, and
8 PL Ø 0.0130
4 PL
Ø 0.0180
Connect Pin 1 to Analog Ground Plane
in This Area for Optimum Performance
any area available must be used when 8 A or greater
operation is desired. Connection from the exposed area of
the PowerPAD to the analog ground plane layer must be
made using 0.013 inch diameter vias to avoid solder
wicking through the vias. Eight vias must be in the
PowerPAD area with four additional vias located under the
device package. The size of the vias under the package,
but not in the exposed thermal pad area, can be increased
to 0.018. Additional vias beyond the twelve recommended
that enhance thermal performance must be included in
areas not under the device package.
Minimum Recommended Thermal Vias: 8 x 0.013 Diameter Inside
Powerpad Area 4 x 0.018 Diameter Under Device as Shown.
Additional 0.018 Diameter Vias May Be Used if Top Side Analog Ground
Area Is Extended.
0.06
0.0150
0.0339
0.0650
0.0500
0.3820 0.3478 0.0500
0.0500
0.2090
0.0256
0.0650
0.0339
0.1700
Minimum Recommended Top
Side Analog Ground Area
0.1340
Minimum Recommended Exposed
Copper Area for Powerpad. 5mil
Stencils May Require 10 Percent
Larger Area
0.0630
0.0400
Figure 10. Recommended Land Pattern for 28-Pin PWP PowerPAD
11
TPS54880
www.ti.com
SLVS450A − OCTOBER 2002 REVISED APRIL 2005
PERFORMANCE GRAPHS
LOAD REGULATION
vs
OUTPUT CURRENT
VO = 0.9 V
VO = 1.2 V
65
VI = 5 V,
TA = 25°C,
FS = 700 kHz
−0.10
−0.15
50
0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7 7.5 8
−0.20
0
1
2
3
4
5
6
IO − Output Current − A
Figure 11
50
150
115
40
120
Gain − dB
90
Phase
60
30
10
Gain
0
−30
−20
−60
VI = 5 V,
IO = 0 A,
fS = 700 kHz
−40
−50
−60
100
1k
10 k
100 k
f − Frequency − Hz
−90
−120
12
4
4.5
TJ = 125°C
fs = 700 kHz
VI = 5 V
Safe Operating Area(1)
75
5.5
55
45
25
0
1
2
3
6
OUTPUT AND INPUT RIPPLE
65
35
4
5
6
7
8
t − Time − 1 µs/div
IO − Output Current − A
Figure 16
VO − Output Voltage −1 V/div
Figure 15
VI = 5 V,
VO = 1.8 V
5
VI − Input Voltage − V
AMBIENT TEMPERATURE
vs
LOAD CURRENT
85
−180
1M
Load Current 2A/div
VO − Output Voltage −100 mV/div
(1)
−0.20
Figure 13
95
−150
LOAD TRANSIENT RESPONSE
Figure 17
8
105
Figure 14
t − Time −20 µs/div
7
Output Ripple − 20 mV/div
125
Phase − Degrees
Ambient Temperature − ° C
180
−30
−0.10
Input Ripple − 100 mV/div
LOOP RESPONSE
0
−10
IO = 0 A
Figure 12
60
20
0
−0.05
−0.15
IO − Output Current − A
30
IO = 6 A
Phase Pin − 2 V/div
55
0
−0.05
0.05
STARTUP TIMING
I/O
VI = 5 V
fs = 700 kHz
CORE
PWRGD(I/O)
PWRGD(CORE)
VO − Output Voltage −1 V/div
60
0.05
0.10
POWER DOWN TIMING
I/O
CORE
PWRGD(I/O)
PWRGD(CORE)
t − Time − 500 µs/div
t − Time −20 µs/div
Figure 18
Figure 19
Safe operating area is applicable to the test board conditions in the Dissipation Ratings
Power Good − 5 V/div
80
0.10
VO = 1.8 V,
TA 25°C,
FS = 700 kHz
0.15
Line Regulation − %
Load Regulation − %
85
70
VI = 5 V,
VO = 1.8 V,
TA = 25°C,
FS = 700 kHz
0.15
VO = 1.8 V
90
Efficiency − %
0.20
0.20
95
75
LINE REGULATION
vs
INPUT VOLTAGE
Power Good − 5 V/div
100
EFFICIENCY
vs
OUTPUT CURRENT
TPS54880
www.ti.com
SLVS450A − OCTOBER 2002 REVISED APRIL 2005
Figure 20 shows the schematic diagram for a power
supply tracking design using a TPS2034 high side power
switch and a TPS54880 device. The TPS2034 power
switch ensures the I/O voltage is not applied to the load
before U1 has enough bias voltage to operate and
generate the core voltage.
TPS2034
Distribution Switch
R2
R4
10 kΩ
71.5 kΩ
R6
9.76 kΩ
C2
1 µF
VIN
C6
10 µF
C7
10 µF
28
27
VOUT_I/O
R1
10 kΩ
U1
RT
AGND
ENA
VSENSE
TRACKIN COMP
VBIAS PWRGD
BOOT
VIN
VIN
PH
26
25
24
23
22
VIN
21
VIN
20 VIN
19
PGND
18
PGND
17 PGND
16 PGND
15 PGND
PwrPad
1
2
3
4
5
6
7
PH
8
PH
9
PH
10
PH
11
PH
12
PH
13
PH
14
PH
R3
R5
C1
470 pF
C4
C5
10 kΩ
R7
C3
301 Ω 470 pF
R8
12 pF
0.047 µF
10 kΩ
9.76 kΩ
L1
R9
0.65 µH
2.2 Ω
VOUT_CORE
C8
22 µF
C9
22 µF
C10
22 µF
C11
3300 pF
Analog and Power Grounds are Tied at
the Power Pad Under the Package of IC
Figure 20. Typical Application With Power Switch
13
TPS54880
www.ti.com
SLVS450A − OCTOBER 2002 REVISED APRIL 2005
DETAILED DESCRIPTION
VOLTAGE REFERENCE
UNDERVOLTAGE LOCK OUT (UVLO)
The voltage reference system produces a precise Vref
signal by scaling the output of a temperature stable
bandgap circuit. During manufacture, the bandgap and
scaling circuits are trimmed to produce 0.891 V at the
output of the error amplifier, with the amplifier connected
as a voltage follower. The trim procedure adds to the high
precision regulation of the TPS54880, since it cancels
offset errors in the scale and error amplifier circuits.
The TPS54880 incorporates an under voltage lockout
circuit to keep the device disabled when the input voltage
(VIN) is insufficient. During power up, internal circuits are
held inactive until VIN exceeds the nominal UVLO
threshold voltage of 3.8 V. Once the UVLO start threshold
is reached, device start-up begins. The device operates
until VIN falls below the nominal UVLO stop threshold of
3.5 V. Hysteresis in the UVLO comparator, and a 2.5-µs
rising and falling edge deglitch circuit reduce the likelihood
of shutting the device down due to noise on VIN.
TRACKIN/INTERNAL SLOW-START
The internal slow-start circuit provides start-up slope
control of the output voltage. The nominal internal
slow-start rate is 25 V/ms. When the voltage on TRACKIN
rises faster than the internal slope or is present when
device operation is enabled, the output rises at the internal
rate. If the reference voltage on TRACKIN rises more
slowly, then the output rises at about the same rate as
TRACKIN.
Once the voltage on the TRACKIN pin is greater than the
internal reference of 0.891 V, the multiplexer switches the
noninverting node to the high precision reference.
ENABLE (ENA)
The enable pin, ENA, provides a digital control enable or
disable (shut down) for the TPS54880. An input voltage of
1.4 V or greater ensures that the TPS54880 is enabled. An
input of 0.82 V or less ensures that device operation is
disabled. These are not standard logic thresholds, even
though they are compatible with TTL outputs.
When ENA is low, the oscillator, slow-start, PWM control
and MOSFET drivers are disabled and held in an initial
state ready for device start-up. On an ENA transition from
low to high, device start-up begins with the output starting
from 0 V.
VBIAS REGULATOR (VBIAS)
The VBIAS regulator provides internal analog and digital
blocks with a stable supply voltage over variations in
junction temperature and input voltage. A high quality,
low-ESR, ceramic bypass capacitor is required on the
VBIAS pin. X7R or X5R grade dielectrics are
recommended because their values are more stable over
temperature. The bypass capacitor must be placed close
to the VBIAS pin and returned to AGND.
External loading on VBIAS is allowed, with the caution that
internal circuits require a minimum VBIAS of 2.70 V, and
external loads on VBIAS with ac or digital switching noise
may degrade performance. The VBIAS pin may be useful
as a reference voltage for external circuits.
14
OSCILLATOR AND PWM RAMP
The oscillator frequency is set internally to 350 kHz. If a
different frequency of operation is required for the
application, the oscillator frequency can be externally
adjusted from 280 to 700 kHz by connecting a resistor
between the RT pin and AGND. The switching frequency
is approximated by the following equation, where R is the
resistance from RT to AGND:
Switching Frequency + 100 kW
R
500 [kHz]
SWITCHING FREQUENCY
(2)
RT PIN
350 kHz, internally set
Float
Externally set 280 kHz to 700 kHz
R = 180 kΩ to 68 kΩ
ERROR AMPLIFIER
The high performance, wide bandwidth, voltage error
amplifier sets the TPS54880 apart from most dc/dc
converters. The user is given the flexibility to use a wide
range of output L and C filter components to suit the
particular application needs. Type 2 or type 3 compensation can be employed using external compensation
components.
PWM CONTROL
Signals from the error amplifier output, oscillator, and
current limit circuit are processed by the PWM control
logic. Referring to the internal block diagram, the control
logic includes the PWM comparator, OR gate, PWM latch,
and portions of the adaptive dead-time and control logic
block. During steady-state operation below the current
limit threshold, the PWM comparator output and oscillator
pulse train alternately reset and set the PWM latch. Once
the PWM latch is reset, the low-side FET remains on for a
minimum duration set by the oscillator pulse width. During
this period, the PWM ramp discharges rapidly to its valley
voltage. When the ramp begins to charge back up, the
low-side FET turns off and high-side FET turns on. As the
PWM ramp voltage exceeds the error amplifier output
voltage, the PWM comparator resets the latch, thus
turning off the high-side FET and turning on the low-side
FET. The low-side FET remains on until the next oscillator
pulse discharges the PWM ramp.
During transient conditions, the error amplifier output
could be below the PWM ramp valley voltage or above the
PWM peak voltage. If the error amplifier is high, the PWM
latch is never reset, and the high-side FET remains on until
TPS54880
www.ti.com
SLVS450A − OCTOBER 2002 REVISED APRIL 2005
the oscillator pulse signals the control logic to turn the
high-side FET off and the low-side FET on. The device
operates at its maximum duty cycle until the output voltage
rises to the regulation set-point, setting VSENSE to
approximately the same voltage as VREF. If the error
amplifier output is low, the PWM latch is continually reset
and the high-side FET does not turn on. The low-side FET
remains on until the VSENSE voltage decreases to a
range that allows the PWM comparator to change states.
The TPS54880 is capable of sinking current continuously
until the output reaches the regulation set-point.
OVERCURRENT PROTECTION
If the current limit comparator trips for longer than 100 ns,
the PWM latch resets before the PWM ramp exceeds the
error amplifier output. The high-side FET turns off and
low-side FET turns on to decrease the energy in the output
inductor and consequently the output current. This
process is repeated each cycle in which the current limit
comparator is tripped.
THERMAL SHUTDOWN
DEAD-TIME CONTROL AND MOSFET
DRIVERS
Thermal shutdown provides protection when an overload
condition is sustained for several milliseconds. With a
persistent fault condition, the device cycles continuously;
starting up by control of the soft-start circuit, heating up due
to the fault condition, and then shutting down upon
reaching the thermal shutdown trip point. This sequence
repeats until the fault condition is removed.
Adaptive dead-time control prevents shoot-through
current from flowing in both N-channel power MOSFETs
during the switching transitions by actively controlling the
turnon times of the MOSFET drivers. The high-side driver
does not turn on until the voltage at the gate of the low-side
FET is below 2 V. While the low-side driver does not turn
on until the voltage at the gate of the high-side MOSFET
is below 2 V.
The high-side and low-side drivers are designed with
300-mA source and sink capability to quickly drive the
power MOSFETs gates. The low-side driver is supplied
from VIN, while the high-side drive is supplied from the
BOOT pin. A bootstrap circuit uses an external BOOT
capacitor and an internal 2.5-Ω bootstrap switch
connected between the VIN and BOOT pins. The
integrated bootstrap switch improves drive efficiency and
reduces external component count.
The cycle-by-cycle current limiting is achieved by sensing
the current flowing through the high-side MOSFET and
comparing this signal to a preset overcurrent threshold.
The high side MOSFET is turned off within 200 ns of
reaching the current limit threshold. A 100-ns leading edge
blanking circuit prevents the current limit from false
tripping. Current limit detection occurs only when current
flows from VIN to PH when sourcing current to the output
filter. Load protection during current sink operation is
provided by thermal shutdown.
The device uses the thermal shutdown to turn off the power
MOSFETs and disable the controller if the junction
temperature exceeds 150°C. The device is released from
shutdown automatically when the junction temperature
decreases to 10°C below the thermal shutdown trip point,
and starts up under control of the slow-start circuit.
POWER-GOOD (PWRGD)
The power good circuit monitors for under voltage
conditions on VSENSE. If the voltage on VSENSE is 10%
below the reference voltage, the open-drain PWRGD
output is pulled low. PWRGD is also pulled low if VIN is
less than the UVLO threshold or ENA is low, or a thermal
shutdown occurs. When VIN ≥ UVLO threshold, ENA ≥
enable threshold, and VSENSE > 90% of Vref, the open
drain output of the PWRGD pin is high. A hysteresis
voltage equal to 3% of Vref and a 35 µs falling edge deglitch
circuit prevent tripping of the power good comparator due
to high frequency noise.
15
PACKAGE OPTION ADDENDUM
www.ti.com
10-Dec-2020
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
(3)
(4/5)
(6)
TPS54880PWP
ACTIVE
HTSSOP
PWP
28
50
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 85
TPS54880
TPS54880PWPR
ACTIVE
HTSSOP
PWP
28
2000
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 85
TPS54880
(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.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of
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