TI TPS40180

TPS40180
www.ti.com
SLVS753B – FEBRUARY 2007 – REVISED NOVEMBER 2007
SINGLE PHASE STACKABLE CONTROLLER
FEATURES
1
• Stackable to 8 Phases, Multiple Controllers
Can Occupy Any Phase
• 2-V to 40-V Power Stage Operation Range
• eTrim™ in System Reference Voltage Trim to
Tighten Overall Output Voltage Tolerance,
Reference is Better Than 0.75% Un-Trimmed
• VDD From 4.5 V to 15 V, With Internal 5-V
Regulator
• Supports Output Voltage From 0.7 V to 5.8 V
• Supports Pre-Biased Outputs
• 10-µA Shutdown Current
• Programmable Switching Frequency up to
1-MHz per Phase
• Current Feedback Control With Forced Current
Sharing (Patents Pending)
• Resistive Divider Sets Input Undervoltage
Lockout and Hysteresis
• True Remote Sensing Differential Amplifier
• Resistive or Inductor’s DCR Current Sensing
CONTENTS
2
APPLICATIONS
•
•
•
•
•
Graphic Cards
Servers
Networking Equipment
Telecommunications Equipment
Distributed DC Power Systems
Description
1
Device Ratings
3
Electrical Characteristics
4
Terminal Information
7
Typical Characteristics
10
Application Information
15
Design Example
35
DESCRIPTION
The TPS40180 is a stackable single-phase
synchronous buck controller. Stacking allows a
modular power supply design where multiple modules
can be connected in parallel to achieve the desired
output power capability if the output power
requirement cannot be provided by one module.
Stacked modules can be configured to switch at
different times while running at the same base
frequency creating a multiple phase supply. Up to
eight phases can be configured, and multiple
modules can be set up to switch on the same phase
if required. Input and output ripple current reduction
occurs as well when modules are stacked. Stacked
modules can be used to generate separate output
rails, load share into a single rail or a combination of
the two while sharing phase information to reduce
ripple currents at the input of the system.
The TPS40180 is optimized for low-output voltage
(from 0.7-V to 5.8-V), high-output current applications
powered from a 2-V to 40-V supply. The TPS40180
converts from 15-V input to 0.7-V output at 1 MHz.
Each phase can be operated at a switching frequency
up to 1 MHz, resulting in an effective ripple frequency
of up to 8 MHz at the input and the output.
With eTrim™, the TPS40180 gives the user the
capability to trim the reference voltage on the device
to compensate for external component tolerances,
tightening the overall system accuracy and allowing
tighter specifications for output voltage of the
converter.
1
2
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.
eTrim 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.
Copyright © 2007, Texas Instruments Incorporated
TPS40180
www.ti.com
SLVS753B – FEBRUARY 2007 – REVISED NOVEMBER 2007
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
PACKAGE (1)
TAPE AND REEL QUANTITY
Plastic 24-Pin QFN (RGE)
(1)
PART NUMBER
250
TPS40180RGET
3000
TPS40180RGER
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.
TYPICAL APPLICATION
24
23
22
21
20
19
COMP CS- CS+ PSELPGOOD CLKIO
1
FB
BOOT 18
VIN(+)
VIN(-)
2
DIFFO
HDRV 17
3
VOUT
SW 16
4
GSNS
5
VSH
6
ILIM
VOUT(+)
TS40180
PVCC 15
LDRV 14
SS
7
VOUT(-)
PGND 13
RT GND BP5 UVLO VDD
8
9
10
11
12
Shutdown
UDG-07029
2
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SLVS753B – FEBRUARY 2007 – REVISED NOVEMBER 2007
DEVICE RATINGS
ABSOLUTE MAXIMUM RATINGS (1)
TPS40180
VI
VO
Input voltage range
Output voltage range
VDD, UVLO, RT, SS
–0.3 to 16
FB, VOUT, GSNS, VSH, ILIM, BP5, PSEL, CS+, CS–, VS+, VS–
–0.3 to 6
BOOT – HDRV
–0.3 to 6
SW, HDRV
–1 to 44
SW, HDRV, transient < 50 ns
–5 to 44
DIFFO, LDRV, PVCC, CLKIO, PGOOD, COMP
–0.3 to 6
PGOOD (eTrim™ usage only)
–0.3 to 22
TJ
Operating junction temperature range
-40 to 150
Tstg
Storage temperature range
-55 to 150
(1)
UNIT
V
V
°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
VI
VDD, UVLO
4.5
SW
–1
BOOT - SW
NOM
40
0
V
5.8
RT
25
PSEL
150
Operating junction temperature
UNIT
15
5.5
All Other Pins
TJ
MAX
-40
105
µA
°C
ELECTROSTATIC DISCHARGE (ESD) PROTECTION
MIN
NOM
MAX
Human Body Model (HBM)
2500
Charged Device Model (CDM)
1500
PACKAGE DISSIPATION RATINGS
(1)
UNIT
V
(1)
THERMAL IMPEDANCE
JUNCTION-TO-AMBIENT
(°C/W)
AIRFLOW (LFM)
TA = 25°C POWER RATING (W)
TA = 85°C POWER RATING (W)
42
Natural Convection
2.38
0.950
35
200
2.85
1.14
32
400
3.10
1.25
Ratings based on JEDEC High Thermal Conductivity (High K) Board. For more information on the test method, see TI Technical Brief
SZZA017.
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SLVS753B – FEBRUARY 2007 – REVISED NOVEMBER 2007
ELECTRICAL CHARACTERISTICS
VVDD = 12V, VBP5 = 5V, VPVCC = 5V, –40°C < TJ < 85°C (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
4.5
12
15
V
50
µA
VDD INPUT SUPPLY
VVDD
Operating voltage range
IVDDSD
Shutdown current
VUVLO < 0.5 V
BP5 INPUT SUPPLY
VBP5
Operating voltage range
IBP5
Operating current
VBP5UV
Rising undervoltage turn on threshold
VBP5UVH
BP5 UVLO hysteresis
4.3
5.0
5.5
2
3
5
4.0
4.25
4.5
225
V
mA
V
mV
PVCC REGULATOR
VPVCC
Output voltage
IPVCC
Output current
4.5 V < VVDD < 15 V
4.3
5.0
0
5.5
V
50
mA
OSCILLATOR
FOSC
Oscillator frequency
RRT= 64.9 kΩ
360
Oscillator frequency range
150
VRMP
Ramp voltage (1)
420
VRTCKLSLV
RT pin clock slave voltage threshold
415
454
1000
500
525
2
kHz
mV
V
DIGITAL CLOCK SIGNAL (CLKIO)
Pull Up Resistance (1)
RCLKH
27
(1)
RCLKL
Pull Down Resistance
ICLKIOLK
Leakage current in high impedance
state (1)
Ω
27
VRT < 2 V, VPSEL = 5 V
1
µA
UVLO PIN
VUVLO(on)
IUVLO
PVCC regulator enabled
0.8
0.9
1.5
PWM switching enabled
1.9
2.0
2.1
9
12
15
Hysteresis bias current
V
µA
PULSE WIDTH MODULATOR
DMAX
tON(min)
Maximum duty cycle
8 phase CLK scheme
87.5%
6 phase CLK scheme
83%
Minimum pulse width (1)
75
ns
VSHARE
VVSH
Current share reference; Ramp valley
voltage
RLOAD = 20 kΩ
1.7
1.8
1.9
V
–200
0
200
nA
695
700
705
mV
ERROR AMPLIFIER
IIB
Input bias current at FB pin
VREF
Trimmed FB control voltage (includes
differential sense amp offset
VFB = 0.7 V
IOH
COMP source current
VCOMP = 1.1V, VFB = 0.6 V
1
2
IOL
COMP sink current
VCOMP = 1.1V, VFB = 0.8 V
1
2
EAGBWP
Gain bandwidth product
AOL
Open loop gain
(1)
(1)
mA
8
12
MHz
60
90
dB
7.5
SOFTSTART
ISS1
Charging Current: device Enabled,
Before First PWM Pulse and During
Hiccup Fault Recovery
6.5
ISS2
Charging Current After First PWM
Pulse
12
VSS_FE
Fault Enable Threshold
VSSSLV
Voltage loop slave mode threshold
voltage
8.2
µA
15
17
0.8
VBP5 = 5V
VBP5 0.75
V
25.5
µA
CURRENT LIMIT
IILIM
(1)
4
Threshold setting current
21.5
23.5
Specified by design. Not production tested .
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SLVS753B – FEBRUARY 2007 – REVISED NOVEMBER 2007
ELECTRICAL CHARACTERISTICS (continued)
VVDD = 12V, VBP5 = 5V, VPVCC = 5V, –40°C < TJ < 85°C (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
0
2.5
UNIT
CURRENT SENSE AMPLIFIER
VISOFST
Input offset voltage
IIB_CS
Input bias current
–2.5
GCS
Gain at PWM Input
VICM
Input common mode range
VDIFFMX
Maximum differential input voltage
100
0.2V ≤ VICM ≤ 5.8V
11.25
12.5
mV
nA
13.75
V/V
0
5.8
V
–60
60
mV
1.005
V/V
DIFFERENTIAL REMOTE VOLTAGE SENSE AMPLIFIER
GRVS
IDIFFOH
Gain
DIFFO source current
IDIFFOL
DIFFO sink current
BWDIFFA
Unity gain bandwidth
RINDIFFA
0.7 V < V(VOUT) – V(GSNS) < 5.8 V
0.995
1.000
V(VOUT) – V(GSNS) = 2 V, V(DIFFO) > 1.98 V,
V(VDD) – V(VOUT) > 2 V
2
V(VOUT) – V(GSNS) = 5.8 V, V(DIFFO) > 5.6 V,
V(VDD) – V(VOUT) = 1 V
1
mA
V(VOUT) – V(GSNS) = 2 V, V(DIFFO) ≥ 2.02 V
(2)
2
5
8
Input resistance, inverting
DIFFO to GSNS
60
Input resistance, noninverting
OUT to GND
60
mA
MHz
kΩ
PSEL PIN
IISEL
Bias current
VMNCLK
Master mode, no output on CLKIO
21.5
23.5
25.5
0
0
0.5
VM8PH
VM6PH
Master mode, 6 phase CLKIO
0.5
0.7
0.9
Master mode, 8 phase CLKIO
0.9
VSSTDBY
Slave mode, standby state
3.4
VS45
Clock slave mode, 8 phase CLKIO, 45°
phase slot (2)
0
0
0.2
VS90
Clock slave mode, 8 phase CLKIO, 90°
phase slot (2)
0.2
0.35
0.5
VS135
Slave mode, 8 phase CLKIO, 135°
phase slot (2)
0.5
0.7
0.9
VS180
Clock slave mode, 8 phase CLKIO,
180° phase slot (2)
0.9
1.1
1.3
VS225
Clock slave mode, 8 phase CLKIO,
225° phase slot (2)
1.3
1.6
1.9
VS270
Clock slave mode, 8 phase CLKIO,
270° phase slot (2)
1.9
2.25
2.6
VS315
Clock slave mode, 8 phase CLKIO,
315° phase slot (2)
2.6
3.0
3.4
VS0
Clock slave mode, 6 phase CLKIO,
0 phase slot (2)
1.9
2.25
2.6
VS60
Clock slave mode, 6 phase CLKIO, 60°
phase slot (2)
0
0
0.2
VS120
Clock slave mode, 6 phase CLKIO,
120° phase slot (2)
0.2
0.35
0.5
VS180
Clock slave mode, 6 phase CLKIO,
180° phase slot (2)
0.5
0.7
0.9
VS240
Clock slave mode, 6 phase CLKIO,
240° phase slot (2)
0.9
1.1
1.3
VS300
Clock slave mode, 6 phase CLKIO,
300° phase slot (2)
1.3
1.6
1.9
(2)
µA
V
Specified by design. Not production tested .
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SLVS753B – FEBRUARY 2007 – REVISED NOVEMBER 2007
ELECTRICAL CHARACTERISTICS (continued)
VVDD = 12V, VBP5 = 5V, VPVCC = 5V, –40°C < TJ < 85°C (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
GATE DRIVERS
RHDRV(on)
HDRV Pull Up Resistance
VBOOT = 5 V, V(SW) = 0 V, IHDRV = 100 mA
RHDRV(off)
HDRV Pull Down Resistance
VBOOT = 5 V, VSW = 0 V, IHDRV = 100 mA
1
2
3
0.5
1
2
RLDRV(on)
LDRV pull up resistance
VPVCC = 5 V, ILDRV = 100 mA
1
2
3.5
RLDRV(off)
LDRV pull down resistance
tHDRV(r)
HDRV rise time
VPVCC = 5 V, ILDRV = 100 mA
0.3
0.75
1.5
25
tHDRV(f)
HDRV fall time (3)
75
25
tLDRV(r)
LDRV rise time (3)
75
25
75
tLDRV(f)
LDRV fall time (3)
10
60
(3)
CLOAD = 3.3 nF
Ω
ns
POWER GOOD
VFBPG_H
Powergood high FB voltage threshold
764
787
798
VFBPG_L
Powergood low FB voltage threshold
591
611
626
VFBPG(hyst)
Powergood threshold hysteresis
TPGDLY
Powergood delay time
VPGL
Powergood low level output voltage
IPG = 2 mA
IPGLK
Powergood leakage current
VPG = 5 V
30
(3)
mV
60
µs
10
0.35
0.40
V
µA
1
OVERVOLTAGE AND UNDERVOLTAGE
VFB_U
FB pin under voltage threshold
565
580
595
VFB_O
FB pin over voltage threshold
792
810
828
126
135
144
mV
THERMAL SHUTDOWN
TTSD
Shutdown Temperature (3)
TTSD(hyst)
Hysteresis (3)
TWRN
Warning Temperature (3)
TWR(hyst)
Hysteresis (3)
(3)
6
40
106
115
124
°C
10
Specified by design. Not production tested .
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SLVS753B – FEBRUARY 2007 – REVISED NOVEMBER 2007
TERMINAL INFORMATION
TERMINAL FUNCTIONS
TERMINAL
NAME
NO.
I/O
DESCRIPTION
FB
1
I
Inverting input to the internal error amplifier. Normally this pin is at the reference voltage of 700 mV.
DIFFO
2
O
Output of the remote sense amplifier. Amplifier is fixed gain of 1 differential mode and is used for output
voltage sensing at the load to eliminate distribution drops.
VOUT
3
I
Positive input to the remote sense amplifier. Amplifier is fixed gain of 1 differential mode and is used for
output voltage sensing at the load to eliminate distribution drops.
GSNS
4
I
Negative input to the remote sense amplifier. Amplifier is fixed gain of 1 differential mode and is used for
output voltage sensing at the load to eliminate distribution drops.
VSH
5
I/O
Pin is either an input or an output. If the chip is configured as a voltage loop master the valley voltage is
output on this pin and is distributed to the slave devices. If configured as a voltage loop slave, the master
VSH pin is connected here and the device uses the master valley voltage reference to improve current
sharing.
ILIM
6
I
Programs the overcurrent limit of the device. Connecting a resistor from this pin to VSH and another to
VOUT on the voltage loop master sets a voltage above VSH. COMP is not allowed to exceed this voltage. If
the load current requirements force COMP to this level for seven clock cycles, an overcurrent event is
declared, and the system shuts down and enter a hiccup fault recovery mode. The controller attempts to
restart after a time period given by seven soft-start cycles.
SS
7
I
Soft-start input. This pin determines the startup ramp time for the converter as well as overcurrent and other
fault recovery timing. The voltage at this pin is applied as a reference to the error amplifier. While this
voltage is below the precision 700 mV reference, it acts as the dominant reference to the error amp
providing a closed loop startup. After it rises above the 700 mV precision reference, the 700 mV precision
reference dominates and the output regulates at the programmed level. In case of an overcurrent event, the
converter attempts to restart after a period of time defined by seven soft-start cycles. Additionally this pin is
used to configure the chip as a voltage loop master or slave. If the pin is tied to VDD or PVCC at power up,
the device is in voltage loop slave mode. Otherwise, the device is a voltage loop master.
RT
8
I
Frequency programming pin. Connecting a resistor from this pin to GND sets the switching frequency of the
device. If this pin is connected to VDD or PVCC, the device is a clock slave and gets its time base from
CLKIO of the clock master device. Phase addressing is done on PSEL.
GND
9
–
Signal level ground connection for the device. All low level signals at the device should be referenced to this
pin. No power level current should be allowed to flow through the GND pin copper areas on the board.
Connect to the thermal pad area, and from there to the PGND copper area.
BP5
10
I
Electrically quiet 5-V supply for the internal circuitry inside the device. If VDD is above 5 V, connect a 20-Ω
resistor from PVCC to this pin and a 100-nF capacitor from this pin to GND. For VDD at 5 V, this pin can be
tied directly to VDD or through a 20-Ω resistor with a 100-nF decoupling capacitor to reduce internal noise.
UVLO
11
I
UVLO input for the device. A resistor divider from VDD sets the turn on voltage for the device. Below this
voltage, the device is in a low quiescent current state. Pulling this pin to ground shuts down the device, and
is used as a system shutdown method.
VDD
12
I
Power input for the LDO on the device.
PGND
13
–
Common connection for the power circuits on the device. This pin should be electrically close to the source
of the FET connected to LDRV. Connected to GND only at the thermal pad for best results.
LDRV
14
O
Gate drive output for the low-side or rectifier FET.
PVCC
15
O
Output of the on board LDO. This is the power input for the drivers and bootstrap circuit. The 5.3-V output
on this pin is used for external circuitry as long as the total current required to drive the gates of the
switching FETs and external loads is less than 50 mA. Connect a 1µF capacitor from this pin to GND.
SW
16
O
This pin is connected to the source of the high-side or switch FET and is the return path for the floating
high-side driver.
HDRV
17
O
Gate drive output for the high-side FET. High-side FET turn-on time must not be greater than minimum
on-time. See electrical characteristics table for the minimum on time of the pulse width modulator.
BOOT
18
I
Bootstrap pin for the high-side driver. A 100-nF capacitor is connected from this pin to SW and provides
power to the high-side driver when the high-side FET is turned on.
CLKIO
19
I/O
Clock and phase timing output while the device is configured as a clock master. In clock slave mode, the
master CLKIO pin is connected to the slave CLKIO pin to provide time base information to the slave.
PGOOD
20
O
Power good output. This open drain output pulls low when the device is in any state other than in normal
regulation. Active soft-start, UVLO, overcurrent, undervoltage, overvoltage or overtemperature warning
(115°C junction) causes this output to pull low.
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TERMINAL FUNCTIONS (continued)
TERMINAL
I/O
DESCRIPTION
NAME
NO.
PSEL
21
I
Phase select pin. For a clock master, a resistor from this pin to GND determines the CLKIO output. When
configured as a clock slave, a resistor from the pin to GND selects the phase relationship that the slave has
with the master. Allowing this pin to float causes the slave to drop off line to shed the phase when current
demands are light for improved overall efficiency. See the Application Information section for more details.
CS+
22
I
Positive input to the current sense amplifier.
CS–
23
I
Negative input to the current sense amplifier
COMP
24
O
Output of the error amplifier.
CS-
GSNS
VSH
ILIM
1
24
VOUT
COMP
DIFFO
FB
TPS40180
RGE PACKAGE
(BOTTOM VIEW)
2
3
4
5
6
23
TPS40180
7
SS
8
RT
9
GND
CS+
22
PSEL
21
10
BP5
PGOOD
20
11
UVLO
VDD
PGND
LDRV
PVCC
SW
HDRV
19
12
18 17 16 15 14 13
BOOT
CLKIO
Figure 1. Device Pin Out
8
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VO
SLVS753B – FEBRUARY 2007 – REVISED NOVEMBER 2007
VSH
RT
CLKIO
5
8
19
PSEL
21
3
+
GSNS
4
DIFFO
2
CLK
Oscillator
17 HDRV
UVLO
Error Amplifier
FB
18 BOOT
Anti-Cross
Conduction
+
1
700 mV
S
+
-
SS
+
16 SW
PWM
Comparator
PVCC
14 LDRV
COMP 24
22
CS-
23
Current Sense
X12.5
VSLAVE
CS+
+
Overvoltage/
Undervoltage
Control
13 PGND
CLK
BP5
23.5 mA
BP5
ILIM
Fault Control
and Soft-Start
6
VDD
7.5 mA
FAULT
10 BP5
20 PGOOD
7.5 mA
PGOOD
Controller
SS
7
BP5
12 mA
2V
140°C
+
UVLO 11
UVLO
110°C
Junction
Temperature
12 VDD
5-V
Regulator
0.9 V
+
15 PVCC
9
UDG-07036
GND
Figure 2. Functional Block Diagram
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TYPICAL CHARACTERISTICS
INPUT SHUTDOWN CURRENT
vs
JUNCTION TEMPERATURE
CURRENT SENSE AMPLIFIER OFFSET VOLTAGE
vs
JUNCTION TEMPERATURE
0.6
VISOFST - Current Sense Offset Voltage - mV
6
IVDD - Input Current - mA
5
4
3
2
1
-30
-10
10
30
50
70
90
0
-0.2
-0.4
-0.6
-30
10
30
50
70
TJ - Junction Temperature - °C
Figure 3.
Figure 4.
RELATIVE CURRENT SENSE GAIN
vs
JUNCTION TEMPERATURE
CURRENT LIMIT
vs
JUNCTION TEMPERATURE
1.0
30 mV
0
60 mV
-0.5
-10
10
30
50
110
90
110
23.5
0.5
-30
90
24.0
23.0
22.5
22.0
21.5
21.0
20.5
5 mV
70
TJ - Junction Temperature - °C
90
110
20.0
-50
Figure 5.
10
-10
TJ - Junction Temperature - °C
CS+ - CS60 mV
30 mV
5 mV
-1.0
-50
0.2
-0.8
-50
110
IILIM - Current Limit Current - mA
GCS - Current Sense Gain - V/V%
0
-50
0.4
-30
-10
10
30
50
70
TJ - Junction Temperature - °C
Figure 6.
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TYPICAL CHARACTERISTICS (continued)
UVLO HYSTERESIS
vs
JUNCTION TEMPERATURE
CURRENT SHARE RE VOLTAGE
vs
JUNCTION TEMPERATURE
1.810
VVSH - Current Share Reference Voltage - V
250
VBP5UVH - UVLO Hysteresis - mV
245
240
235
230
225
220
215
210
205
200
-50
-30
-10
10
30
50
70
90
1.805
1.800
1.795
1.790
-50
110
-30
TJ - Junction Temperature - °C
50
70
90
110
90
110
SOFTSTART CHARGE CURRENT
vs
JUNCTION TEMPERATURE
REMOTE VOLTAGE SENSE AMPLIFIER
vs
JUNCTION TEMPERATURE
GRVS - Remote Voltage Sense Amplifier Gain - V/V
ISSx - Soft-Start Charge Current - mA
30
Figure 8.
15
13
ISS2
11
ISS1
9
7
-30
10
Figure 7.
17
5
-50
-10
TJ - Junction Temperature - °C
-10
10
30
50
70
90
110
0.05
0.04
0.03
0.02
0.01
0
-0.01
-0.02
-0.03
-0.04
-0.05
-50
TJ - Junction Temperature - °C
Figure 9.
-30
-10
10
30
50
70
TJ - Junction Temperature - °C
Figure 10.
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TYPICAL CHARACTERISTICS (continued)
DRIVER RESISTANCE
vs
JUNCTION TEMPERATURE
POWER GOOD THRESHOLD VOLTAGE
vs
JUNCTION TEMPERATURE
2.0
900
RxDRV - Driver Resistance - W
1.8
1.6
VFBPG - Power Good FB Threshold Voltage - V
RHDRV(on)
RHDRV(off)
RLDRV(on)
RLDRV(off)
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
-50
-30
-10
10
30
50
70
90
750
High
700
Low
650
600
550
-30
10
30
50
70
TJ - Junction Temperature - °C
Figure 11.
Figure 12.
POWER GOOD LOW THRESHOLD VOLTAGE
vs
JUNCTION TEMPERATURE
POWER GOOD FB HYSTERESIS
vs
JUNCTION TEMPERATURE
IOUT = 4 mA
600
500
IOUT = 2 mA
400
300
200
100
-10
10
30
50
70
90
110
90
110
40
30
20
10
0
-50
-30
90
50
-30
110
TJ - Junction Temperature - °C
Figure 13.
12
-10
TJ - Junction Temperature - °C
VFBPG(hyst) - Power Good FB Hysteresis - mV
VPGL - Power Good Low Threshold Voltage - mV
800
500
-50
110
700
0
-50
850
-10
10
30
50
70
TJ - Junction Temperature - °C
Figure 14.
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TYPICAL CHARACTERISTICS (continued)
UNDERVOLTAGE AND OVERVOLTAGE THRESHOLD
vs
JUNCTION TEMPERATURE
UVLO ENABLE THRESHOLD
vs
JUNCTION TEMPERATURE
980
VUVLO - Undervoltage Lockout Threshold - V
VVFB_x - Feedback Voltage Thresholds - mV
900
850
800
750
Overvoltage
700
650
Undervoltage
600
550
500
450
400
-50
-30
-10
10
30
50
70
90
960
940
920
900
880
860
840
820
-50
110
-30
-10
10
30
50
70
90
TJ - Junction Temperature - °C
TJ - Junction Temperature - °C
Figure 15.
Figure 16.
UVLO HYSTERESIS CURRENT
vs
JUNCTION TEMPERATURE
UVLO PWM ENABLE THRESHOLD VOLTAGE
vs
JUNCTION TEMPERATURE
110
2.025
12.0
VUVLO - UVLO PWM Enable Threshold - V
11.8
IUVLO - Hysteresis Current - mA
11.6
11.4
11.2
11.0
10.8
10.6
10.4
2.020
2.015
Enable
2.010
2.005
2.000
Disable
1.995
1.990
10.2
10.0
-50
-30
-10
10
30
50
70
90
110
1.985
-50
TJ - Junction Temperature - °C
Figure 17.
-30
-10
10
30
50
70
90
110
TJ - Junction Temperature - °C
Figure 18.
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TYPICAL CHARACTERISTICS (continued)
FEEDBACK BIAS CURRENT
vs
JUNCTION TEMPERATURE
0.30
50
0.25
45
0.20
40
IIB - Feedback Bias Current - nA
VFB - Relative Feedback Voltage Change - %
RELATIVE FEEDBACK REFERENCE VOLTAGE CHANGE
vs
JUNCTION TEMPERATURE
0.15
0.10
0.05
0
-0.05
-0.10
35
30
25
20
15
10
-0.15
-0.20
-50
5
-30
-10
10
30
50
70
90
0
-50
110
-30
TJ - Junction Temperature - °C
-10
10
30
50
70
90
110
TJ - Junction Temperature - °C
Figure 19.
Figure 20.
RELATIVE OSCILLATOR FREQUENCY
vs
JUNCTION TEMPERATURE
5
fOSC - Relative Oscillator Frequency - %
4
3
3
1
0
-1
-2
-3
-4
-5
-50
-30
-10
10
30
50
70
90
110
TJ - Junction Temperature - °C
Figure 21.
14
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APPLICATION INFORMATION
Introduction
The TPS40180 is a versatile single-phase controller that can be used as a building block for a more complex
power system, or as a stand alone power supply controller. In either system, the TPS40180 provides an excellent
power conversion solution and supports such features as pre-bias startup, intelligent fault handling capability with
graceful shutdown and restart even with multiple modules sharing a common load. Remote load voltage sense
for improved load regulation where it counts, at the load, thermal shutdown, remote enable and power good
indication features help solve the problems faced by the power supply designer. To ease application to a specific
task, there are several user programmable features including closed loop soft-start time, operating frequency and
current limit level.
More complex power solutions are readily supported by the TPS40180. The device can be configured to run in a
master/slave configuration where a master can control several slaves. Several options are possible including a
single output multiple phase supply sharing phase timing information to reduce input and output ripple, a multiple
output supply that shares phase switching timing information to reduce input ripple currents and a combination
approach that has multiple outputs sharing phase information where each output can use multiple phases. Phase
information in all cases comes from a single device designated the clock master. Current sharing information is
passed from the device designated voltage loop master for each output to the slaves for that particular output rail
by connecting the COMP pin of the master to the COMP pin of the slaves. The clock master is also the voltage
loop master in one of the rails of a multiple output supply; whereas, the other rails are controlled by a voltage
loop master that is a clock slave to the single clock master device.
Programming the Operating Frequency
A resistor is connected from the RT pin to GND to select the operating frequency of the converter. The
relationship between the desired operating frequency and the timing resistance is given by Equation 1:
RRT =
3.675 ´ 105
(fSW )2
+
2.824 ´ 104
- 5.355
fSW
(1)
where
•
•
RRT is the timing resistance in kΩ
fSW is the desired switching frequency in kHz
If this is a clock master, the switching frequency above is the per-phase switching frequency.
Programming the soft-start Time
The soft-start time is programmable by connecting a capacitor from the SS pin to GND. An internal current
source charges this capacitor providing a linear ramp voltage. This ramp voltage is the effective reference to the
error amplifier while it is less that the 700-mV internal reference. The time required for the SS pin to ramp from
GND to 700 mV is the soft-start time. For outputs that are not pre-biased, that time is given in Equation 2.
V
´ CSS
TSS = REF
ISS
(2)
where
•
•
•
tSS is the soft-start time in seconds
CSS is the capacitor from SS to GND in µF
ISS is the soft-start current in µA, 15-µA typical
If the output of the converter has a pre-existing voltage on it, the device the soft-start happens a little differently.
The SS pin current is held to a lower value than normal until the PWM becomes active. This occurs as the SS
pin voltage exceeds the FB pin voltage and the COMP pin moves up into the ramp range, causing the first pulse.
At that point, the SS pin current is shifted to 15 µA nominal. Figure 22 and Figure 23 illustrate this.
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SS
VVDD
0.8
Voltage - V
ISS2
FB
0.7
FB
SS
ISS1
0
VOUT
Voltage - V
VREG
VPRE-BIAS
VOUT
PGOOD
0
t0
t1
t - Time
t2
t3
Figure 22. Soft-Start Waveform for Pre-Biased Outputs
VOUT
From CS
Amplifier
R1
0.7 V
1
7
FB
SS
Error Amplifier
+
+
COMP
+ U3
+
PWM
Logic
RBIAS
CSS
ISS2
ISS1
Q
S
Q
R
Fault, UVLO,
Overtemperature
UDG-07023
Figure 23. Soft-Start Implementation
Using Figure 22 provides:
16
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t1 =
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CSS æ VPREBIAS ´ RBAIS ö
´ç
÷
ISS1 è
R1 + RBIAS
ø
(3)
æV
CSS æ
´ RBIAS
´ ç VREF - ç PREBIAS
ç
ISS2 è
R1 + RBIAS
è
t2 =
öö
÷ ÷÷
øø
(4)
TSS = t1 + t2
(5)
where
•
•
•
•
•
•
t1 is the time to the first PWM pulse in seconds
t2 is the time from the first PWM pulse until regulation in seconds
C(SS) is the SS pin capacitor in µF
I(SS1) is the SS1 pin charging current in µA, 7.5 µA
I(SS2)is the SS2 pin charging current in µA,15 µA
TSS is the total soft-start time
Tracking
The TPS40180 can function in a tracking mode, where the output tracks some other voltage. To do this, a
voltage divider is connected from the voltage to be tracked to GND, with the tap of the divider connected to the
SS pin of the TPS40180. See Figure 24. The capacitors C1 and C2 are required for two purposes. First they
provide a means for timing of overcurrent restart attempts. Second, they provide for matching output voltage
ramp up rate of the TPS40180 to the controlling external supply.
R5
C3
R4
TPS40180
R3
2
DIFFO
1
FB
C4
R6
24 COMP
C5
R1
C1
+
ISS
7
VEXT
-
SS
R2
C2
UDG-07027
Figure 24. Tracking Setup
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When choosing component values, the SS pin current (ISS) must be accounted for in order to prevent an offset in
the output of the TPS40180 converter and the tracked supply.
æ
ö
VREF
æ R3 ö
´ R2 ´ ç
R1 = ç
÷
÷
ç
÷
è R5 ø
è VREF - (ISS ´ R2 ) ø
(6)
where
•
•
•
R1, R2, R3 and R5 are in Ω
VREF is the reference voltage of the TPS40180 (700 mV)
I(SS) is the SS pin current (15µA typical)
To use Equation 6, R3 and R5 must be known from the design of the compensation network and nominal
converter output voltage. R2 is then chosen arbitrarily. A value between 1 kΩ and 10 kΩ is suggested. Too large
a value and the tracking error is greater. Too small, and the requirements for C2 and C2 become excessive.
Once R1 and R2 have been chosen, C1 and C2 can be chosen. The R1-C1 time constant and the R2 C2 time
constant should match.
R1 ´ C1 = R 2 ´ C 2
(7)
Absolute matching of the time constants is not necessary for Equation 7. The nearest standard values of
capacitor provides satisfactory results. Pick a value for C1 or C2 and find the closest corresponding standard
value for the other capacitor.
Current Sensing and Overcurrent Detection
The TPS40180 uses the current sensing architecture shown in Figure 25.
IOUT
CS+
CS-
22
23
TPS40180
VC
+
CS gain = 12.5
+
COMP
24
+
-
E/A
+
Ve
S
+
PWM
Ramp
VSH
5
23.5 mA
R1
ILIM
0.5 V
+
+
1.8 V
S
+
0V
+
6
R2
Overcurrent
VOUT
UDG-07028
Figure 25. Current Sense Architecture
The sense resistor can either be a resistor between the inductor and the output capacitor(s) or an R-C filter
across the inductor.
18
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Overcurrent protection for the TPS40180 is set by connecting a resistor from the ILIM pin to the VSH pin. A
current source of 23.5 µA out of the ILIM pin sets a voltage level on the ILIM pin and the COMP pin is not
allowed to rise above this level. Since the device uses current mode control and COMP cannot rise above this
level, an effective maximum output current is defined. The second resistor on the ILIM pin, R2, is optional and if
used is connected to the output voltage. This resistor provides compensation of the overcurrent level for changes
in output voltage, such as would be seen at startup. If not used, the overcurrent threshold level is higher at
output voltages lower than the designed target.
The output current, flows through the inductor resistance and develops a voltage, VC across it, representative of
the output current. This resistance voltage is extracted from the total inductor voltage by the R-C network placed
across the inductor. This voltage is amplified with a gain of 12.5 and then subtracted from the error amplifier
output, COMP, to generate the Ve voltage. The Ve signal is compared to the slope-compensation RAMP signal
to generate the PWM signal that is used to control the FET drivers. As the output current is increased, the
amplified VC causes the Ve signal to decrease. In order to maintain the proper duty cycle, the COMP signal must
increase. Therefore, the magnitude of the COMP signal contains the output current information as shown in
Equation 8 through Equation 10:
COMP = Ve + (Ipk ´ RL ) ´ 12.5
(8)
æ (VIN - VOUT ) ö æ VOUT
IRIPPLE = ç
÷´
ç
÷ ç VIN
L
è
ø è
ö æ 1 ö
÷
÷´ç
ø è fSW ø
(9)
æI
ö
IPK = ç RIPPLE ÷ + IOUT
2
è
ø
(10)
In order to satisfy the input-output voltage relationship, the Equation 11 must hold:
V
Ve = VRMP ´ OUT + VVSH
VIN
(11)
Combining Equation 8 and Equation 11 and solving for the COMP voltage gives:
æV
ö
COMP = VRMP ´ ç OUT ÷ + VVSH + (IPK ´ RL ) ´ 12.5
è VIN ø
(12)
Since COMP and ILIM are of equal voltage when at the current limit condition, setting ILIM to the expected
COMP voltage at maximum current is how the current limit threshold is set. To calculate the resistors R1 and R2
from Figure 25, proceed as follows:
æV
ö
a = ç RMP ÷
è VIN ø
(13)
æ V
b = RL ´ 12.5 ´ IPK + ç RMP
ç 2´N
ph
è
(
R1 =
ö
÷
÷
ø
)
(14)
b + a ´ VVSH
(1 - a )´ IILIM
(15)
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R2 =
b + a ´ VVSH
a ´ IILIM
(16)
where (for Equation 8 through Equation 16)
•
•
•
•
•
•
•
•
•
•
•
•
COMP is the voltage on the COMP pin
VRMP is the ramp amplitude, 500 mV
VOUT is the output voltage of the converter
IOUT is the dc output current of the converter
VIN is the input voltage of the converter
VVSH is the valley voltage of the ramp, 1.8V
IPK is the peak current in the inductor
RL is the DC resistance of the inductor
L is the inductance of the inductor
12.5 is the gain of the current sense amplifier network inside the device
Nph is the number of phase that the master clock is set to, either 6 or 8
IILIM is the bias current out of the ILIM pin, 23.5µA typical
The TPS40180 architecture inherently allows multiple modules to start simultaneously into a load without
problems with overcurrent tripping. The reason this is the case is the master device in a group of devices
configured as a multiphase power supply is the only device that retains overcurrent control. The slave devices do
not have the ability to initiate an overcurrent event but rely on the master to handle this function. For this reason,
when setting the overcurrent threshold for a multiple converter system, the above equations should be used to
set the threshold on a per-converter basis. For example, if four converters are being used to generate a supply
that has a 60A current limit, the current limit to use for calculating the resistors would be 15 A.
NOTE:
The above equations indicate that the overcurrent threshold is dependent on input
voltage. Consequently, as the input voltage increases, the overcurrent threshold also
rises.
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Hiccup Fault Recovery
To reduce the input current and component dissipation during on overcurrent event, a hiccup mode is
implemented. Hiccup mode refers to a sequence of 7 soft-start cycles where no MOSFET switching occurs, and
then a re-start is attempted. If the fault has cleared, the re-start results in returning to normal operation and
regulation. This is shown in Figure 26.
VVDD
SS
1.5 V
(A)
0.5 V
GND
VIN
(B)
SW NODE
GND
VOUT, REG
(C)
VOUT
GND
ILIM
(D)
COMP
t0 t1 t2
t3
UDG-07024
Figure 26. Hiccup Recovery From Faults
Normal operation is occurring between t0 and t1 as shown by VOUT at the regulated voltage, (C) and normal
switching on the SW NODE (B) and COMP at its nominal level, (D). At t1, an overcurrent load is experienced.
The increased current forces COMP to increase to the ILIM level as shown in (D). If the COMP voltage is above
the ILIM voltage for 7 switching cycles, the controller enters a hiccup mode at t2. During this time the controller is
not switching and the power MOSFETs are turned off. The SS pin goes through 7 cycles of charging and
discharging the soft-start capacitor. At the end of the 7 cycles the controller attempts another normal re-start. If
the fault has been cleared, the output voltage comes up to the regulation level as shown at time t3. If the fault
has not cleared, the COMP voltage again rises above the ILIM voltage and a fresh hiccup cycle starts. This
condition may continue indefinitely.
The pre-bias circuitry is reset at this time and the restart does not discharge an output pre-bias condition if it
exists.
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Selecting Current Sense Network components
Some consideration must be given to selecting the components that are used to sense current in the converter. If
an R-C filter across the inductor is used, the R-C time constant should match the natural time constant of the
inductor. Equation 17 and Figure 27 describe the relationship.
æ L ö
RCS ´ CCS = ç
÷
è RL ø
(17)
Inductor
L
RL
CCS
RCS
+
VC
_
UDG-07033
Figure 27. Current Sense Network
The amplitude of the VC voltage must also be considered. If the VC voltage is expected to rise above 60 mV at
the desired overcurrent threshold, an attenuator should be used to keep the voltage to a maximum of 60 mV. To
implement the divider, place a resistor in parallel with CCS. The time constant of the whole network should remain
the same as the L/R time constant of the inductor.
High ripple current applications can also cause problems under certain conditions. When the sensing network is
matched to the inductor, the ripple voltage on the capacitor CCS is the same as the ripple voltage produced on
the effective inductor resistance. If this ripple component is too great, sub-harmonic instability can result and the
PWM exhibits excessive jitter or give a long pulse, short pulse type of output. To minimize this effect, the slope of
the signal presented to the current sense amplifier must be less than a maximum value. This places a minimum
limit on what the inductor L/R time constant can be for a given application as shown in Equation 18. If the chosen
inductor and other application parameters fall outside these recommendations, it is necessary to attenuate the
current feedback signal with an extra resistor.
(
)
æ L ö GCS(max) ´ VIN + (2 ´ VOUT )
ç
÷>
fSW
è RL ø
(18)
where
•
•
•
•
•
•
22
L is the inductance in H
RL is the equivalent series resistance of the inductor in Ω
GCS(max) is the maximum gain of the current sense amplifier, 13.75
VIN is the input voltage in V
VOUT is the output voltage in V
fSW is the switching frequency in Hz
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PGOOD Functionality
PGOOD functions as a normal open drain power good output on an device configured as a master. This is an
open drain signal and pulls low when any condition exists that would indicate that the output of the supply might
be out of regulation. These conditions include:
• FB pin more that ±15% from nominal
• soft-start is active
• A UVLO condition exists for the TPS40180
• The TPS40180 has detected a short circuit condition
• The TPS40180 die is over warning temperature threshold (115°C)
If the device is configured as a voltage loop slave, PGOOD pulls low the following conditions only:
• A UVLO condition exists for the TPS40180
• The TPS40180 die is over warning temperature threshold (115°C)
Note that when there is no power to the device, PGOOD is not able to pull close to GND if an auxiliary supply is
used for the power good indication.
Output Overvoltage and Undervoltage Protection
If the output voltage is sensed to be too low, the TPS40180 turns off the power FETs, and initiate a hiccup restart
sequence just as if a fault condition had occurred. The sensing of the output voltage is done using the FB pin
and the undervoltage threshold voltage for the FB pin is 580-mV typical. The pre-bias circuitry is reset at this time
and the restart does not discharge an output pre-bias condition if it exists.
The TPS40180 also includes an output overvoltage protection mechanism. This mechanism is designed to turn
on the low-side FET when the FB pin voltages exceeds the overvoltage protection threshold of 810-mV (typical).
The high side FET turns off and the low-side FET turns on and stays on until the voltage on the FB drops below
the undervoltage threshold. At this point, the controller enters a hiccup recovery cycle as in the undervoltage
case. The output overvoltage protection scheme is active at all times. If at any time when the controller is
enabled, the FB pin voltage exceeds the overvoltage threshold, the low-side FET turns on until the FB pin
voltage falls below the undervoltage threshold.
Overtemperature Protection
When the TPS40180 die temperature exceeds 115°C, the PG pin is pulled low as a warning that temperatures
are becoming excessive. Systems can act on this indication as appropriate.
The TPS40180 shuts down if the die temperature is sensed to be more than 135°C. The die must cool to less
than the warning level reset of 105°C before the device restarts. The device restarts automatically after the die
cools to this level.
eTRIM™
The TPS40180 incorporates an innovative new feature that allows the user to trim the reference voltage in
system. This allows the user to tighten overall output tolerances by trimming out errors caused by resistor divider
and other system tolerances. The reference has been designed so that it may be trimmed without affecting
temperature drift so that the user can perform system level trims without worrying about creating a situation
where the reference temperature drift becomes a problem. Trimming in the TPS40180 is done with a small bank
of EEPROM. Changing bit values in this EEPROM causes parameters, like reference voltage, inside the device
to change. Once trim is accomplished, there is no need to trim again, the change is permanent (but can be
overwritten by subsequent trimming operations). The eTrim™ trimming mechanism has been designed so that
the user can only program the reference voltage so that any errors in the programming sequence does not affect
other factory set trims such as current feedback gain for example. This provides a secure environment for the
user to use and eliminates the possibility that other parameters could inadvertently changed.
The adjustment range is ±14 mV from the untrimmed level. The reference is pre-trimmed at the factory to ±0.5%
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of nominal so further trim is not necessary unless it is desired to further reduce total system errors. This factory
trim uses the same eTrim™ mechanism that can be used at the system or converter level and changes the same
bits that the user changes if using eTrim™. Consequently, not all of the trim range may be available to make
adjustments in system as the factory trim sets the bits to the value that provides the correct nominal reference
voltage. Typically, the trim has at least 3 steps remaining in any direction to allow for user system level trim.
There are several steps required to use the eTrim™ feature. A typical trim sequence would flow as follows:
1. Power up the system and wait for the system to stabilize in steady state
2. Program the TPS40180 reference trim to a default setting (overwriting factory trim)
3. Measure the system output voltage
4. Calculate a correction factor to be applied to the output voltage
5. Program the EEPROM inside the TPS40180 with the new trim code
6. Measure the new system output voltage
7. Repeat from step 4 if required
The TPS40180 provides 4 trim bits available for user programming. The bits and their effect on the untrimmed
reference value are given in Table 1.
Table 1. eTrim Bit Codes and Effect
eTrim™ REFERENCE BIT CODE
(1)
b3
b2
b1
b0
REFERENCE
CHANGE (mV)
1
0
0
0
+14
1
0
0
1
+12
1
0
1
0
+10
1
0
1
1
+8
1
1
0
0
+6
1
1
0
1
+4
1
1
1
0
+2
1
1
1
1
0 (1)
0
0
0
0
0
0
0
0
1
–2
0
0
1
0
–4
0
0
1
1
–6
0
1
0
0
–8
0
1
0
1
–10
0
1
1
0
–12
0
1
1
1
–14
Default setting
The process of writing to the on chip trim EEPROM is as follows. With power applied to the system and the
system in steady state:
1. Force the input voltage to the device, VVDD, to a level of 7 V (this eases stresses on the UVLO pin).
2. Raise the UVLO pin to a level 2 V above VVDD and PGOOD to 20 V
3. Apply a pulse of VVDD + 4V for a minimum of 10 µs to UVLO
4. Bring UVLO to VVDD + 2 V for at least 8 µs
5. The UVLO pin is then pulsed to VVDD + 4 V seven times (six address bits and one data bit) for each bit that is
to be written. The pulse period is typically 1 µs and the width of the pulse determines whether the pulse is
interpreted as a 1 or as a 0 by the EEPROM circuitry.
6. Data has been placed in a buffer. To finalize the writing, pull PGOOD to 20 V and the UVLO pin to VVDD + 4
V for at least 15 ms.
Figure 28 shows a typical sequence.
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VVDD
‘0’ programmed to bit 0
‘1’ programmed to bit 1
A5 A4 A3 A2 A1 A0 D
A5 A4 A3 A2 A1 A0 D
VVDD+4 V
VVDD+2 V
UVLO
> 2.5 V
Settle Time
>=15 ms
15 ms write EEPROM
>10ms >8ms 1ms 1ms
20 V
PGOOD
UDG-07032
Figure 28. eTrim™ EEPROM Programming Sequence
The pulses from VVDD + 2 V to VVDD + 4 V on UVLO are governed by the timing shown in Figure 29.
Note that there are six address bits in the sequence to write to a single EEPROM bit. To write to the eTrim™
accessible bits, the address sequence must be correct for all six bits or else the write attempt has no effect. To
write to eTrim™ accessible bits the first four address bits must be zero. Anything else is not accepted. Address
bits A1 and A0 select which eTrim™ accessible EEPROM bit is written. For example, to write a 1 to bit 3 of the
eTrim™ accessible bits, the data pulse sequence would look like Figure 30.
A5
A4
A3
A2
A1
A0
0
0
0
0
1
1
D
100 ns
‘0’
1
UDG-07038
900 ns
‘1’
1 ms
UDG-07037
Figure 29. eTrim™ Bit Pulse Timing
Figure 30. Write 1 to Bit 3
As data is clocked into the device, the reference voltage reflects the updates without writing the data buffer to the
actual EEPROM. System measurements can be made after a suitable system dependent settling time has
elapsed after changing the bits in the buffer. When satisfied with the results, the EEPROM may be written by
pulling PGOOD to 20 V and UVLO to V(VDD) + 4 V for at least 15 ms. For best reliability, the EEPROM should
only be written to by pulling PGOOD to 20V and UVLO to V(VDD) + 4V a maximum of three times during the
product lifetime. This writing only needs to be done once during the entire trimming cycle, after the optimal trim
values are found since data clocked in will affect the output without perfoming the actual write. Until written,
changes are not permanent and will be lost after power cycling the device.
Using the Device for Clock Master/Slave Operation
The TPS40180 can be operated as either a master clock source or a slave to a master clock.
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Table 2. RT Voltage and Clock Master/Slave
RT VOLTAGE (VRT) (V)
CLOCK MODE
< 0.5
Master (or single converter)
> 2 (tied to PVCC or VDD)
Slave
In the clock master mode, the master clock frequency is set by connecting a resistor from the RT pin to GND. In
the clock master mode, the PSEL pin selects the CLKIO operating mode for the device. There are three possible
states defined in Table 3.
Table 3. PSEL Pin Modes for Clock Master
PSEL RESISTANCE to GND
(kΩ)
MODE
0
No CLKIO. CLKIO does not send out pulses.
OPEN
8 phase CLKIO. CLKIO send out a pulse train for interleaving with 45° phase separation
29.4
6 phase CLKIO. CLKIO send out a pulse train for interleaving with 60° phase separation
In the clock slave mode, the CLKIO pin is an input. The controller fires in a fixed relationship to the master
determined by the resistance placed from PSEL to GND, or is turned off to improve efficiency at light load. The
actual result depends on how the master CLKIO is programmed.
Table 4. PSEL Phase Programming for Slave With 8
Phase Master Clock
PHASE ANGLE (°)
PSEL RESISTANCE to GND (kΩ)
Standby
OPEN
45
0
90
14.7
135
29.4
180
47
225
68
270
95.3
315
127
Table 5. PSEL Phase Programming for Slave With 6
Phase Master Clock
PHASE ANGLE (°)
PSEL RESISTANCE to GND (kΩ)
Standby
OPEN
0
95.3
60
0
120
14.7
180
29.4
240
47
300
68
When a slave senses any level change on the PSEL pin that would indicate a change in firing angle, it
momentarily goes into standby mode. When a slave leaves standby mode, it starts supplying current after 64
clock cycles have elapsed if the status of the PSEL pin has not changed from when the device entered standby
mode. In this way, a slave can have its firing angle dynamically changed depending on operating conditions. A
slave can be held in standby mode by allowing the PSEL pin to float.
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Using the TPS40180 for Voltage Control Loop Master or Slave Operation
The TPS40180 can function as a voltage loop master or as a voltage loop slave. As a voltage loop master, the
TPS40180 behaves like a standard control device in that it regulates its output using its internal error amplifier
and reference. As a voltage loop slave, the TPS40180 takes the VSH and COMP signals from a voltage loop
master and the slave converter becomes an output current booster to the master converter. Current is shared
between the master and slave since both the current command reference (VSH) and the current command
(COMP) are being distributed form the master controller and used by the slave to set its output current. The error
amplifier in the master is responsible for overall voltage regulation. The error amplifier on the slave is
disconnected when configured as a voltage control loop slave.
To configure a TPS40180 as a voltage loop slave, connect the SS pin to VDD or PVCC. It is important that the
SS pin not fall more than 1 V below the PVCC voltage when starting up as a slave. If this condition is no met, the
controller may not start. For this reason, it is not recommended to tie SS to BP5 to configure the converter as a
voltage control loop slave.
Connections Between Controllers for Stacking
One of the main benefits of using the TPS40180 is the ability to parallel output power stages to achieve higher
output currents and to scale or stack on controllers as needed. Phasing information is also shared among the
controllers to minimize input ripple and RMS current in the input stage capacitors. Figure 31 shows the
connections among the controller devices and the controller configuration connections to implement a single
output stacked configuration. Up to 7 slave controllers can be connected to the master controller in this manner
with unique phasing for each controller. More than 7 controllers can also be connected as long as some of them
are programmed to operate at the same phase relationship with respect to the master. Not shown are the power
stage portions of the schematics. The outputs of the individual converters inductors are simply connected
together and then to a common output capacitor bank. All other connections would be as for a single device used
as a converter.
In Figure 31, the master controller is configured as a CLK master and as a voltage control loop master (SS and
RT pin connections). The slave controllers are configured as CLK slaves (RT pin tied to PVCC) and as voltage
control loop slaves (SS pin tied to PVCC).
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TPS40180
Master
2
DIFFO
1
FB
PSEL 21
VDD 15
24 COMP
RT
8
SS
7
19 CLKIO
5
VSH
TPS40180
Slave
10 kW
2
DIFFO
1
FB
24 COMP
PSEL 21
VDD 15
19 CLKIO
RT
8
5
SS
7
VSH
TPS40180
Slave
2
DIFFO
1
FB
24 COMP
PSEL 21
VDD 15
19 CLKIO
RT
8
5
SS
7
VSH
TPS40180
Slave
2
DIFFO
1
FB
24 COMP
PSEL 21
VDD 15
19 CLKIO
RT
8
5
SS
7
VSH
UDG-07031
Figure 31. Single Output Stacked Configuration
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The 10-kΩ resistor connected from the CLKIO line to GND is required to ensure that the CLKIO line falls to GND
quickly when the master device is shutdown or powers off. The master CLKIO pin goes to a high impedance
state at these times and if the CLKIO line was high, there is no other active discharge part. The slave controllers
look at the CLKIO line to determine if the system is supposed to be running or not. A level below 0.5V on CLKIO
is required for this purpose. If the CLKIO line remains high after that master is shut down, the slaves continue to
operate. This is seen as the slave LDRV signal remaining high for a period of time after the master is shut down
and results in output voltage excursions that are not controlled.
NOTE:
In any system configured to have a CLK master and CLK slaves, a 10-kΩ resistor
connected from CLKIO to GND is required.
For simplicity of design, the compensation components shown on the master, as well as the components
connected to the RT and SS pins may be present on the slaves. This prevents separate designs being
necessary for master and slave circuits. The RT and SS pins can have jumper option to tie them to VDD to
program an individual device as a slave. These components were omitted in Figure 31.
Selection of the PSEL pin resistors is simple. First determine if the master should generate a CLK signal that is
suitable for 60 or 45 spacing of the phases. Select the appropriate PSEL connection option from Table 3. For the
slaves, determine the desired firing angle for each one and pick the appropriate resistor from either Table 4 or
Table 5 depending on the clock scheme chosen for the master.
Design Note: When used in a master/slave relationship and an overvoltage event occurs, only the control loop
master turns on the low-side FET to pull down the output voltage. This results in the master phase low-side FET
sinking all of the combined maximum current for the slaves. For example, if the per phase current limit is 10 A
and there are 4 phases, the master low-side FET could be required to pass 30 A for a brief time. The master
error amplifier is still active during this time and tries to have the slaves regulate the output voltage. As the
master COMP pin rises to the ILIM point, a fault event is sensed and the converter shuts down, and then initiate
a hiccup restart. Size the master low-side FET to handle the appropriate amount of surge current for 7 clock
cycles of the converter.
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A connection diagram for several controllers sharing phase information and synchronized to each other but
having different output voltages is shown in Figure 32. This is similar to the previous example but here the
controllers are all control loop masters (SS not pulled to VDD) and control their own output voltages
independently. One device is configured as a CLK master (RT not tied to VDD) and is the clock generator for the
CLK slaves. Picking the PSEL resistors is the same as before. overcurrent in this configuration depends on
which controller senses the overcurrent event. If one of the CLK slaves experiences a fault, that converter only
shuts down, and enter the hiccup restart mode. If the CLK master controller senses an overcurrent, it stops
sending CLKIO pulses to the slaves, causing them to stop. The master then enters a hiccup recovery mode.
TPS40180
CLK Master
2
DIFFO
1
FB
PSEL 21
VDD 15
24 COMP
RT
8
SS
7
19 CLKIO
10 kW
5
VSH
TPS40180
CLK Slave
2
DIFFO
1
FB
PSEL 21
VDD 15
24 COMP
19 CLKIO
5
RT
8
SS
7
VSH
TPS40180
CLK Slave
2
DIFFO
1
FB
PSEL 21
VDD 15
24 COMP
19 CLKIO
5
RT
8
SS
7
VSH
UDG-07034
Figure 32. Phase Share Multiple Output Configuration
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Finally, a configuration diagram for multiple multiphase converters is shown in Figure 33. This is just a
combination of the two previous examples and should follow intuitively once those are understood. It is the
example of Figure 31 with a CLK slave but control loop master added to create a second output voltage while
sharing phasing information with the first converter group. A slave has been added to the second control loop
master controller in this case as well creating a grouping of controllers that provide a second output voltage. This
can have a significant impact on the required input filter capacitance if all the converters are located close to one
another.
VOUT1
VOUT2
TPS40180
CLK Master
Loop 1 Master
2
DIFFO
1
FB
TPS40180
CLK Slave
Loop 2 Master
PSEL 21
VDD 15
RT
24 COMP
DIFFO
1
FB
SS
TPS40180
Slave
1
FB
24 COMP
RT
8
SS
7
19 CLKIO
7
5
DIFFO
VDD 15
24 COMP
VSH
2
PSEL 21
8
19 CLKIO
5
2
VSH
TPS40180
Slave
10 kW
PSEL 21
VDD 15
2
DIFFO
1
FB
24 COMP
PSEL 21
VDD 15
19 CLKIO
RT
8
19 CLKIO
RT
8
5
SS
7
5
SS
7
VSH
VSH
TPS40180
Slave
2
DIFFO
1
FB
24 COMP
PSEL 21
VDD 15
19 CLKIO
RT
8
5
SS
7
VSH
UDG-07035
Figure 33. Multiple Multiphase Configuration
VSH Line in the Multiphase
The examples in Figure 31 through Figure 33 show the VSH line distributed among the various controllers
comprising a single output voltage grouping. This is the recommended practice for best results. However, if the
ground potential difference between the controllers is not great (no more that 10 mV), distribution of VSH among
the controllers in a particular output voltage group may not be necessary. VSH is the valley voltage of the
controller and distributing it provides a known current reference signal among the controllers that when compared
with the distributed COMP signal from the master, serves to better balance the current among the modules. If the
ground potential between modules in the same output voltage grouping is small enough, there error contributed
by not distributing the VSH signal becomes on the order of systematic errors already present and its usefulness
is diminished. A decision must be made on an individual application basis.
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LAYOUT CONSIDERATIONS
Power Stage
A synchronous BUCK power stage has two primary current loops. One is the input current loop which carries
high AC discontinuous current adn the other is the output current loop carrying a high DC continuous current.
The input current loop includes
capacitors and the ground path
generally good practice to place
MOSFET and the source of the
MOSFETs.
the input capacitors, the main switching MOSFET, the inductor, the output
back to the input capacitors. To keep this loop as small as possible, it is
some ceramic capacitance directly between the drain of the main switching
synchronous rectifier (SR) through a power ground plane directly under the
The output current loop includes the SR MOSFET, the inductor, the output capacitors, and the ground return
between the output capacitors and the source of the SR MOSFET. As with the input current loop, the ground
return between the output capacitor ground and the source of the SR MOSFET should be routed under the
inductor and SR MOSFET to minimize the power loop area.
The SW node area should be as small as possible to reduce the parasitic capacitance and minimize the radiated
emissions.
The gate drive loop impedance (HDRV-gate-source-SW and LDRV-gate-source- GND) should be kept to as low
as possible. The HDRV and LDRV connections should widen to 20mils as soon as possible out from the IC pin.
Device Peripheral
The TPS40180 provides separate signal ground (GND) and power ground (PGND) pins. It is required to separate
properly the circuit grounds. The return path for the pins associated with the power stage should be through
PGND. The other pins especially for those sensitive pins such as FB, RT and ILIM should be through the low
noise GND. The GND and PGND plane are suggested to be connected at the output capacitor with single 20 mil
trace.
A minimum 0.1-µF ceramic capacitor must be placed as close to the VDD pin and AGND as possible with at
least 15 mil wide trace from the bypass capacitor to the GND.
A 4.7-µF ceramic capacitor should be placed as close to the PVCC pin and PGND as possible.
BP5 is the filtered input from the PVCC pin. A 4.7-Ω resistor should be connected between PVCC and BP5 and a
1-µF ceramic capacitor should be connected from BP5 to GND. Both components should be as close to BP5 pin
as possible.
When a DCR sensing method is applied, the sensing resistor is placed close to the SW node. It is connected to
the inductor with Kelvin connection. The sensing traces from the power stage to the chip should be away from
the switching components. The sensing capacitor should be placed very close to the CS+ and CS- pins. The
frequency setting resistor should be placed as close to RT pin and GND as possible. The VOUT and GSNS pins
should be directly connected to the point of load where the voltage regulation is required.
A parallel pair of 10-mil traces connects the regulated voltage back to the chip. They should be away from the
switching components. The PowerPAD should be electrically connected to GND.
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C5
R1
C7
R2
TPS40180
R11
R9
COMP 24
1
FB
2
DIFFO
CS- 23
VSNS
3
VOUT
CS+ 22
GSNS
4
GSNS
PSEL 21
5
VSH
PGOOD 20
6
ILIM
CLKIO 19
R6
R5
R8
C6
C8
PSEL
R3
R7
BP5
C17
VIN
R13
SS
BOOT 18
8
RT
HDRV 17
9
GND
C9
CLKIO
SW
R12
7
VOUT
D1
HDRV
SW 16
10 BP5
PVCC 15
11 UVLO
LDRV 14
12 VDD
PGND 13
C15
R16
R15
LDRV
C19
PWP
C18
C20
R18
UDG-07051
Figure 34. TPS40180 Peripheral Schematic
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AGND
AGND
I LI M
I LI M
VSNS
GSNS
AGND
VOUT
BP5
AGND
PSEL
PGOOD
CS+
VI N
BP5
CLKI O
PGND LDRV
PVCC
PVCC
AGND
PGOOD
PVCC
SW HDRV
BP5
PGND
SW
Figure 35. TPS40180 Recommended Layout for Peripheral Components
PowerPad Layout™
The PowerPAD™ package provides low thermal impedance for heat removal from the device. The PowerPAD™
derives its name and low thermal impedance from the large bonding pad on the bottom of the device. The circuit
board must have an area of solder-tinned-copper underneath the package. The dimensions of this area depend
on the size of the PowerPAD™ package. Thermal vias connect this area to internal or external copper planes
and should have a drill diameter sufficiently small so that the via hole is effectively plugged when the barrel of the
via is plated with copper. This plug is needed to prevent wicking the solder away from the interface between the
package body and the solder-tinned area under the device during solder reflow. Drill diameters of 0.33 mm (13
mils) works well when 1-oz copper is plated at the surface of the board while simultaneously plating the barrel of
the via. If the thermal vias are not plugged when the copper plating is performed, then a solder mask material
should be used to cap the vias with a diameter equal to the via diameter plus 0.1 mm minimum. This capping
prevents the solder from being wicked through the thermal vias and potentially creating a solder void under the
package. Refer to PowerPAD™ Thermally Enhanced Package for more information on the PowerPAD™
package
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DESIGN EXAMPLE
Single Output Configuration from 12-V to 1.5-V DC-to-DC Converter Using a TPS40180
The following example illustrates the design process and component selection for a single output synchronous
buck converter using TPS40180. The design goal parameters are given in the table below. A list of symbol
definitions is found at the end of this section.
Design Goal Parameters
SYMBOL
PARAMETER
TEST CONDITION
VIN
Input voltage
VOUT
Output voltage
VRIPPLE
Output ripple
IOUT
Output current
fSW
Switching frequency
MIN
10.8
IOUT=20A
TYP
MAX
UNIT
12
13.2
V
1.5
V
30
mV
20
A
280
kHz
Inductor Selection
The inductor is determined by the desired ripple current. The required inductor is calculated by:
L=
VIN(max) - VOUT
IRIPPLE
´
VOUT
1
´
VIN(max) fSW
(19)
Typically the peak to peak inductor current IRIPPLE is selected to be around 25% of the rated output current. In
this design, IRIPPLE is targeted at 25% of IOUT. The calculated inductor is 0.95 µH and in practical a 1uH inductor
with 1.7 mΩ DCR from Vishay is selected. The real inductor ripple current is 4.7 A.
Step 2: Output Capacitor Selection
The output capacitor is typically selected by the output load transient response requirement. Equation 20
estimates the minimum capacitor to reach the under voltage requirement with load step up. Equation 21
estimates the minimum capacitor for over voltage requirement with load step down. When VIN(min)< 2×VOUT, the
minimum output capacitance can be calculated using Equation 20. Otherwise, Equation 21 is used.
COUT(min) =
ITRAN(max)2 ´ L
(VIN(min) - VOUT )´ VUNDER
(20)
when VIN(min)<2×VOUT
C OUT(min) =
ITRAN(max)2 ´ L
VOUT ´ VOVER
(21)
when VIN(min)>2×VOUT
In this design, VIN(min) is much larger than 2×VOUT, so Equation 21 is used to determine the minimum
capacitance. Based on a 8-A load transient with a maximum of 60 mV deviation, a minimum 711-µF output
capacitor is required. In the design, four 220-µF, 4-V, SP capacitor are selected to meet this requirement. Each
capacitor has an ESR of 5 mΩ.
Another criterion for capacitor selection is the output ripple voltage. The output ripple is determined mainly by the
capacitance and the ESR.
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æ
ö
IRIPPLE
VRIPPLE(TotOUT) - ç
÷
VRIPPLE(TotOUT) - VRIPPLE(COUT)
8
C
f
´
´
OUT
SW ø
è
=
ESRCo =
IRIPPLE
IRIPPLE
(22)
With an 880-µF output capacitance, the ripple voltage at the capacitor is calculated to be 1.5 mV. In the
specification, the output ripple voltage should be less than 30 mV, so based on Equation 22, the required
maximum ESR is 9.4 mΩ. The selected capacitors can meet this requirement.
Step 3: Input Capacitor Selection
The input voltage ripple depends on input capacitance and ESR. The minimum capacitor and the maximum ESR
can be estimated by:
CIN(min) =
ESRCin =
IOUT ´ VOUT
VRIPPLE(Cin) ´ VIN ´ fSW
(23)
VRIPPLE(CinESR)
IOUT + 12 IRIPPLE
(24)
For this design, assume VRIPPLE(Cin) is 100 mV and VRIPPLE(CinESR) is 50 mV, so the calculated minimum
capacitance is 89 µF and the maximum ESR is 2.3 mΩ. Choosing four 22 µF, 16 V, 2mΩ ESR ceramic
capacitors meets this requirement.
Another important thing for the input capacitor is the RMS ripple current rating. The RMS current in the input
capacitor is estimated by:
IRMS _ CIN =
D ´ (1 - D) ´ IOUT
(25)
where
•
D is the duty cycle
The calculated RMS current is 6.6 A. Each selected ceramic capacitor has a RMS current rating of 4.3 A, so it is
sufficient to reach this requirement.
MOSFET Selection
The MOSFET selection determines the converter efficiency. In this design, the duty cycle is very small so that
the high-side MOSFET is dominated with switching losses and the low-side MOSFET is dominated with
conduction loss. To optimize the efficiency, choose smaller gate charge for the high-side MOSFET and smaller
RDS(on) for the low-side MOSFET. RENESAS HAT2167H and HAT2164H are selected as the high-side and
low-side MOSFET respectively. The power losses in the high-side MOSFET is calculated with the following
equations:
The RMS current in the high-side MOSFET is
2
æ
I
Isw rms = D ´ ç IOUT 2 + RIPPLE
ç
12
è
ö
÷ = 7.08 A
÷
ø
(26)
The RDS(on)(sw) is 9.3 mΩ when the MOSFET gate voltage is 4.5 V. The conduction loss is:
2
PSW(cond) = (ISWrms ) ´ RDS(on)(sw) = 0.47 W
(27)
The switching loss is:
PSW(sw) =
IPK ´ VIN ´ fSW ´ RDRV ´ (QgdSW + QgsSW )
= 0.35 W
Vgtdrv
(28)
The calculated total loss is the high-side MOSFET is:
36
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PSW(tot) = PSW(cond) + PSW(SW ) = 0.82 W
(29)
The RMS current in the low-side MOSFET is:
2
æ
I
ISRrms = (1 - D) ´ ç IOUT 2 + RIPPLE
ç
12
è
ö
÷ = 18.7A
÷
ø
(30)
The RDS(on)(sr) of each HAT2164 is 4.4 mΩ when the gate voltage is 4.5 V. Two HAT2164 FETs are used in this
design.
The conduction loss in the low-side MOSFETs is:
2 æ RDS(on)(sr)
PSR(cond) = (ISRrms ) ´ ç
ç
2
è
ö
÷÷ = 0.77 W
ø
(31)
The total power loss in the body diode is:
PD IO D E = 2 ´ IO U T ´ t D ´ V f ´ fS W = 0.39 W
(32)
Therefore, the calculated total loss in the SR MOSFETs is:
PSR(tot) = PSR(cond) + PDIODE = 1.16 W
(33)
Peripheral Component Design
Switching Frequency Setting (RT)
RT =
3.675 ´ 105
(fSW )2
+
2.824 ´ 104
- 5.355 = 100kW
fSW
(34)
In the design, a 95.3 kΩ resistor is selected. The actual switching frequency is 280 kHz.
Output Voltage Setting (FB)
Substitute the top resistor R1 with 10 kΩ in the following equation , and then calculate the bottom bias resistor.
RBIAS = 0.7 ´
R1
= 8.66kW
VOUT - 0.7
(35)
Current Sensing Network Design (CS+, CS-)
Choosing C1 a value for 0.1µF, and calculating R with the following equations.
R=
L
= 6kW
DCR ´ C1
(36)
Overcurrent Protection (ILIM)
ILIM pin is connected to VSH and VOUT pins with R1 and R2 respectively. Equation 15 and Equation 16 are
used to calculate the over current setting resistors. The DC over current rating is set at 28 A. The calculated
values are 41 kΩ and 830 kΩ for R1 and R2 respectively. In the final design, R1 and R2 are chosen as 36.5 kΩ
and 787 kΩ for temperature and other tolerances compensation.
VREG (PVCC)
A 4.7-µF capacitor is recommended to filter noise.
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BP5
A 4.7-Ω resistor and 1-µF capacitor is placed between VREG and BP5 as a low pass filter.
Phase Select (PSEL)
If the board is configured as a clock master for a multiphase application, an 8-phase CLKIO signal is generated if
PSEL pin is open, and a 6-phase CLKIO signal is generated if PSEL is tied to ground with a 29.4-kΩ resistor. If
the board is stacked as a slave for a multiphase application, a different resistor value is selected. The PSEL
resistor selection is illustrated in the previous datasheet section.
VSHARE (VSH)
A 1-µF capacitor is tied from VSHARE to GND.
Powergood (PGOOD)
The PGOOD pin is tied to BP5 with a 10-kΩ resistor.
Undervoltage Lockout (UVLO)
UVLO is connected to the input voltage with a resistor divider. The two resistors have the same value of 10 kΩ.
When the input voltage is higher than 2 V, the internal linear regulator is enabled.
Clock Synchronization (CLKIO)
CLKIO is floating as no clock synchronization required for single output configuration.
Bootstrap Capacitor
A bootstrap capacitor is connected between the BOOT and SW pin. The bootstrap capacitor depends on the
total gate charge of the high side MOSFET and the amount of droop allowed on the bootstrap capacitor
Qg
= 55nF
DV
CBOOT =
(37)
Qg is 11 nC and is 0.2 V in the calculation. For this application, a 0.1-µF capacitor is selected.
Soft-Start (SS)
To get about 1-ms soft-start time, a 22-nF capacitor is tied to SS pin.
I ´T
CSS = SS SS = 22nF
V REF
(38)
ISS is the soft-start current which is 15- µA typically. VREF is the reference voltage 0.7 V.
Remote Sense
VOUT and GSNS are connected to the remote sensing output connector. DIFFO is connected to the output
voltage setting resistor divider. If the differential amplifier is not used, VOUT and GSNS are suggested to be
grounded, and DIFFO is left open.
Feedback Compensator Design
Peak current mode control method is employed in the controller. A small signal model is developed from the
COMP signal to the output.
GVC(s) =
(s ´ COUT ´ ESR + 1)´ ROUT
1
1
´
´
DCR ´ A C s ´ ts + 1
s ´ COUT ´ ROUT + 1
(39)
The time constant is defined by:
38
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ts =
SLVS753B – FEBRUARY 2007 – REVISED NOVEMBER 2007
T
æ
ç
ln ç
ç æ VRAMP
çç
èè T
æ VRAMP ö æ VOUT ö
ç T ÷ - ç L ÷ ´ DCR ´ AC
è
ø è
ø
æ 2 ´ VOUT
ö æ VIN - VOUT ö
´ DCR ´ A C - ç
÷
÷-ç
L
L
ø è
ø
è
ö
÷
÷
÷
ö
÷ ´ DCR ´ A C ÷
ø
ø
(40)
Equation 40 is applied when the PWM pulse width is shorter than the current loop delay. The current loop delay
is typically 100ns.
ts =
T
æ æ VRAMP ö æ VIN - VOUT ö
ö
çç
÷ ´ DCR ´ AC ÷
÷+ç
T
L
ø è
ø
÷
ln ç è
ç æ VRAMP ö æ VOUT ö
÷
-ç
´ DCR ´ A C
ç ç
÷
÷
÷
è è T ø è L ø
ø
(41)
Equation 41 is applied when the PWM pulse width is longer than the current loop delay. The current loop delay is
typically 100ns. Equation 42 is used in this design because the PWM pulse width is much larger than the current
loop delay. The low frequency pole is calculated by:
1
fVCP1 =
2 ´ p ´ COUT ´ ROUT
= 2.36kHz
(42)
The ESR zero is calculated by:
fESR =
1
2 ´ p ´ COUT ´ ESR
= 176.8kHz
(43)
In this design, a Type II compensator is employed to compensate the loop.
VREF
+
R1
C1
R2
C2
Figure 36. Type II Compensator
The compensator transfer function is:
Gc(s) =
1
´
R1´ (C1 + C2)
s ´ R2 ´ C2 + 1
æ
æ (C1´ C2 ) ö ö
+ 1÷
s ´ ç s ´ R2 ´ ç
ç (C1 + C2 ) ÷÷ ÷
ç
è
ø ø
è
(44)
The loop gain transfer function is:
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TV (s ) = G C(s ) ´ G VC(s )
(45)
Assume the desired crossover frequency is 25 kHz, then set the compensator zero about 1/10 of the crossover
frequency and the compensator pole equal to the ESR zero. The compensator gain is then calculated to achieve
the desired bandwidth. In this design, the compensator gain, pole and zero are selected using Equation 46
through Equation 49.
fP =
fZ =
1
= 176.8kHz
æ (C1´ C2 ) ö
2 ´ p ´ R2 ´ ç
÷÷
ç
è (C1 + C2 ) ø
(46)
1
= 2.5kHz
2 ´ p ´ R2 ´ C2
(47)
TV (j ´ 2 ´ p ´ fC ) = 1
(48)
From Equation 48, the compensator gain is solved as 4.5 ×10 .
5
A CM =
1
= 6.29 ´ 104
R1´ (C1 + C2 )
(49)
Set R1 equal to 10 kΩ, and then calculate all the other components.
• R2=40 kΩ
• C1=22 pF
• C2=1.6 nF
In the real laboratory practice, the final components are selected as following to increase the phase margin and
reduce PWM jitter.
• R1=10 kΩ
• R2=39 kΩ
• C1=22 pF
• C2=2.7nF
HAT2167H
+
HAT2164 H
Figure 37. Single Output Converter Schematic
40
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EFFICIENCY
vs
LOAD CURRENT
OUTPUT VOTLAGE
vs
LOAD CURRENT
1.530
100
VIN
90
10.8 V / 12 V
13.2 V
1.525
VOUT - Output Voltage - V
80
h - Efficiency - %
70
1.520
60
1.515
50
40
1.510
30
VIN
20
13.2 V
10.8 V
12 V
10
1.505
1.500
0
0
2
4
6
8
10
12
14
16
18
20
0
2
4
6
8
10
12
14
16
ILOAD - Load Current - A
ILOAD - Load Current - A
Figure 38. Efficiency Curve
Figure 39. Output Load Regulation
18
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41
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SLVS753B – FEBRUARY 2007 – REVISED NOVEMBER 2007
HAT2167H
+
HAT2164H
TPS40180 Converter Block
VIN
VOUT
VIN
FB
VOUT
FB
SS
SS
GND
GND
TPS40180 Converter Block I
TPS40180 Converter Block II
Figure 40. Additional Application Circuit I: Simultaneous Tracking with TPS40180 Devices
VO1 = 3.3 V
VO1 = 3.3 V
VO2 = 1.5 V
VO2 = 1.5 V
VSS2
(500 mV/div)
VPGOOD2
(2 V/div)
VPGOOD2
(2 V/div)
Figure 41. Simultaneously Tracking Up
42
VSS2
(500 mV/div)
Figure 42. Simultaneously Tracking Down
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In Figure 43, Block I and Block II are configured as master and slave respectively.
HAT2167H
+
HAT2164H
TPS40180 Converter Block
VIN
RT
SS
VOUT
CLKIO
PSEL
VIN
CLKIO
RT
SS
GND
TPS40180 Converter Block I
VOUT
PSEL
GND
TPS40180 Converter Block II
Figure 43. 2-Phase Single Output Schematic with TPS40180, VIN=12V, VOUT=1.5 V, IOUT=40 A;
Master SW Node
(5 V/div)
Slave SW Node
(5 V/div)
Master SW Node
(5 V/div)
Slave SW Node
(5 V/div)
CLKIO
(5 V/div)
Inductor Currents
(5 A/div)
Figure 44. Switch Node and CLKIO Waveforms
Figure 45. Current Balance at 0 A to 16 A Load Step Up,
2.5 A/µs Slew Rate
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Table 6. Definitions
SYMBOL
DESCRIPTION
VIN(min)
Minimum Operating Input voltage
VIN(max)
Maximum Operating Input Voltage
VOUT
Output Voltage
IRIPPLE
Inductor Peak-Peak Ripple Current
ITRAN(max)
Maximum Load Transient
VUNDER
Output Voltage Undershot
VOVER
Output Voltage Overshot
VRIPPLE(totOUT)
Total Output Ripple
VRIPPLE(COUT)
Output Voltage Ripple Due to Output Capacitance
VRIPPLE(CIN)
Input Voltage Ripple Due to Input Capacitance
VRIPPLE(CinESR)
Input Voltage Ripple Due to the ESR of Input Capacitance
PSW(cond)
High Side MOSFET Conduction Loss
ISWrms
RMS Current in the High Side MOSFET
RDS(on)(SW)
“ON” Drain-Source Resistance of the High Side MOSFET
PSW(sw)
High Side MOSFET Switching Loss
IPK
Peak Current Through the High Side MOSFET
RDRV
Driver Resistance of the High Side MOSFET
QgdSW
Gate to Drain Charge of the High Side MOSFET
QgsSW
Gate to Source Charge of the High Side MOSFET
VGSW
Gate Drive Voltage of the High Side MOSFET
PSW(gate)
Gate Drive Loss of the High Side MOSFET
QgSW
Gate Charge of the High Side MOSFET
PSW(tot)
Total Losses of the High Side MOSFET
PSR(cond)
Low Side MOSFET Conduction Loss
ISRrms
RMS Current in the Low Side MOSFET
RDS(on)(SR)
“ON” Drain-Source Resistance of the low Side MOSFET
PSR(gate)
Gate Drive Loss of the Low Side MOSFET
QgSR
Gate Charge of the Low Side MOSFET
VgSR
Gate Drive Voltage of the Low Side MOSFET
PDIODE
Power Loss in the Diode
tD
Dead Time Between the Conduction of High and Low Side MOSFET
Vf
Forward Voltage Drop of the Body Diode of the Low Side MOSFET
PSR(tot)
Total Losses of the Low Side MOSFET
DCR
Inductor DC Resistance
AC
Gain of the Current Sensing Amplifier, typically it is 13
ROUT
Output Load Resistance
VRAMP
Ramp Amplitude, typically it is 0.5V
T
Switching Period
GVC(s)
Control to Output Transfer Function
GC(s)
Compensator Transfer Function
TV(s)
Loop Gain Transfer Function
ACM
Gain of the Compensator
fP
The Pole Frequency of the Compensator
fZ
The Zero Frequency of the Compensator
44
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Additional References
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PACKAGE OPTION ADDENDUM
www.ti.com
8-Nov-2007
PACKAGING INFORMATION
Orderable Device
Status (1)
Package
Type
Package
Drawing
Pins Package Eco Plan (2)
Qty
TPS40180RGER
ACTIVE
QFN
RGE
24
3000 Green (RoHS &
no Sb/Br)
CU NIPDAU
Level-2-260C-1 YEAR
TPS40180RGERG4
ACTIVE
QFN
RGE
24
3000 Green (RoHS &
no Sb/Br)
CU NIPDAU
Level-2-260C-1 YEAR
TPS40180RGET
ACTIVE
QFN
RGE
24
250
Green (RoHS &
no Sb/Br)
CU NIPDAU
Level-2-260C-1 YEAR
TPS40180RGETG4
ACTIVE
QFN
RGE
24
250
Green (RoHS &
no Sb/Br)
CU NIPDAU
Level-2-260C-1 YEAR
Lead/Ball Finish
MSL Peak Temp (3)
(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)
Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check
http://www.ti.com/productcontent for the latest availability information and additional product content details.
TBD: The Pb-Free/Green conversion plan has not been defined.
Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements
for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered
at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.
Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and
package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS
compatible) as defined above.
Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame
retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material)
(3)
MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder
temperature.
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is
provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the
accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and continues to take
reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on
incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited
information may not be available for release.
In no 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 by TI
to Customer on an annual basis.
Addendum-Page 1
PACKAGE MATERIALS INFORMATION
www.ti.com
12-Jan-2008
TAPE AND REEL BOX INFORMATION
Device
Package Pins
Site
Reel
Diameter
(mm)
Reel
Width
(mm)
A0 (mm)
B0 (mm)
K0 (mm)
P1
(mm)
W
Pin1
(mm) Quadrant
TPS40180RGER
RGE
24
SITE 41
330
12
4.3
4.3
1.5
8
12
Q2
TPS40180RGET
RGE
24
SITE 41
180
12
4.3
4.3
1.5
8
12
Q2
Pack Materials-Page 1
PACKAGE MATERIALS INFORMATION
www.ti.com
12-Jan-2008
Device
Package
Pins
Site
Length (mm)
Width (mm)
TPS40180RGER
RGE
24
SITE 41
346.0
346.0
29.0
TPS40180RGET
RGE
24
SITE 41
190.5
212.7
31.75
Pack Materials-Page 2
Height (mm)
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