PTH08T250WAS_技术文档

PTH08T250W

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SLTS278B–JUNE 2007–REVISED AUGUST 2007

50-A, 4.5-V to 14-V INPUT, NON-ISOLATED,

WIDE-OUTPUT, ADJUSTABLE POWER MODULE WITH TurboTrans™

1

FEATURES

•

Multi-Phase, Switch-Mode Topology

TurboTrans™ Technology

2

•

Up to 50-A Output Current

•

4.5-V to 14-V Input Voltage

Designed to meet Ultra-Fast Transient

Requirements up to 300 A/μs

Wide-Output Voltage Adjust (0.7 V to 3.6 V)

±1.5% Total Output Voltage Variation

Efficiencies up to 96%

•

SmartSync Technology

Parallel Operation

Output Overcurrent Protection

(Nonlatching, Auto-Reset)

APPLICATIONS

•

Complex Multi-Voltage Systems

Servers

Workstations

•

Operating Temperature: –40°C to 85°C

Safety Agency Approvals: (Pending)

–

UL/IEC/CSA-C22.2 60950-1

•

Prebias Startup

On/Off Inhibit

Differential Output Voltage Remote Sense

Adjustable Undervoltage Lockout

Auto-Track™ Sequencing

DESCRIPTION

The PTH08T250W is a high-performance 50-A rated, non-isolated power module. This module represents the

2nd generation of the popular PTH series power modules with a reduced footprint and improved features.

Operating from an input voltage range of 4.5 V to 14 V, the PTH08T250W requires a single resistor to set the

output voltage to any value over the range, 0.7 V to 3.6 V. The wide input voltage range makes the

PTH08T250W particularly suitable for advanced computing and server applications that utilize a loosely

regulated 8-V to 12-V intermediate distribution bus. Additionally, the wide input voltage range increases design

flexibility by supporting operation with tightly regulated 5-V, 8-V, or 12-V intermediate bus architectures.

The module incorporates a comprehensive list of features. Output overcurrent and over-temperature shutdown

protects against most load faults. A differential remote sense ensures tight load regulation. An adjustable

under-voltage lockout allows the turn-on voltage threshold to be customized. Auto-Track™ sequencing is a

popular feature that greatly simplifies the simultaneous power-up and power-down of multiple modules in a

power system. Additionally, the capability to current share between multiple PTH08T250W modules allows for

load currents greater than 50A on a single rail.

The PTH08T250W includes new patent pending technologies, TurboTrans™ and SmartSync. The TurboTrans

feature optimizes the transient response of the regulator while simultaneously reducing the quantity of external

output capacitors required to meet a target voltage deviation specification. Additionally, for a target output

capacitor bank, TurboTrans can be used to significantly improve the regulators transient response by reducing

the peak voltage deviation. SmartSync allows for switching frequency synchronization of multiple modules, thus

simplifying EMI noise suppression tasks and reducing input capacitor RMS current requirements.

The module uses double-sided surface mount construction to provide a low profile and compact footprint.

Package options include both through-hole and surface mount configurations that are lead (Pb) - free and RoHS

compatible.

1

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of

Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

2

TurboTrans, Auto-Track, TMS320 are trademarks 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.

PTH08T250W

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SLTS278B–JUNE 2007–REVISED AUGUST 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.

STANDARD APPLICATION

Auto-Track

R

TT

1%

0.05 W

(Optional)

20

2

3

5

19

V

I

Track

Share Comp CLKIO TT

6

7

V

I

+Sense

+Sense 17

V

O

14

15

10

11

V

O

PTH08T250W

Inhibit

+

C

O

660 mF

(Required)

21 Inhibit/UVLO

22 SmartSync

Config

-Sense 16

L

O

A

D

GND

12

AGND

V Adj

+

O

1

8

9

13

4

18

C

I

1000 mF

(Required)

-Sense

GND

R

SET

1%, 0.05 W

(Required)

GND

UDG-07002

A. When operating at an input voltage greater than 8V the minimum required input capacitance may be reduced to

560μF.

2

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ORDERING INFORMATION

For the most current package and ordering information, see the Package Option Addendum at the end of this datasheet, or see

the TI website at www.ti.com.

DATASHEET TABLE OF CONTENTS

DATASHEET SECTION

ENVIRONMENTAL AND ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS TABLE (PTH08T250W)

TERMINAL FUNCTIONS

PAGE NUMBER

3

4

6

TYPICAL CHARACTERISTICS (V_I= 12V)

TYPICAL CHARACTERISTICS (V_I= 5V)

ADJUSTING THE OUTPUT VOLTAGE

INPUT & OUTPUT CAPACITOR RECOMMENDATIONS

TURBOTRANS™ INFORMATION

SOFT-START POWER-UP

7

8

9

11

15

19

20

21

23

26

27

30

32

REMOTE SENSE

OUTPUT INHIBIT

OVERCURRENT PROTECTION

OVER-TEMPERATURE PROTECTION

SYCHRONIZATION (SMARTSYNC)

AUTO-TRACK SEQUENCING

UNDERVOLTAGE LOCKOUT (UVLO)

CURRENT SHARING

CURRENT SHARING LAYOUT

PREBIAS START-UP

TAPE & REEL AND TRAY DRAWINGS

ENVIRONMENTAL AND ABSOLUTE MAXIMUM RATINGS

(Voltages are with respect to GND)

UNIT

V_trackTrack pin voltage

–0.3 to V_I+ 0.3

–40 to 85

V

T_A

Operating temperature range Over V_Irange

AH suffix

AD suffix

AS suffix

AZ suffix

Surface temperature of module body or pins for

5 seconds maximum.

T_waveWave soldering temperature

T_reflowSolder reflow temperature

260

°C

235⁽¹⁾

260⁽¹⁾

–55 to 125⁽²⁾

500

Surface temperature of module body or pins

T_stg

Storage temperature

Mechanical shock

Per Mil-STD-883D, Method 2002.3 1 msec, 1/2 AH and AD suffix

sine, mounted

AS and AZ suffix

125

G

Mechanical vibration

Weight

Mil-STD-883D, Method 2007.2 20-2000 Hz

20

16.7

grams

Flammability

Meets UL94V-O

(1) During reflow of surface mount package version do not elevate peak temperature of the module, pins or internal components above the

stated maximum.

(2) The shipping tray or tape and reel cannot be used to bake parts at temperatures higher than 65C.

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ELECTRICAL CHARACTERISTICS

PTH08T250W

T_A= 25°C, V_I= 12 V, V_O= 3.3 V, C_I= 1000 µF, C_O= 660 µF, and I_O= I_Omax (unless otherwise stated)

PARAMETER

TEST CONDITIONS

PTH08T250W

UNIT

MIN

TYP

MAX

48

25°C, natural convection

60°C, 200 LFM

0

I_O

Output current

Over V_Orange

A

V

50

(1)

0.7 ≤ V_O< 1.2

1.2 ≤ V_O≤ 3.6

4.5

0.7

14

V_I

Input voltage range

Over I_Orange

14

V_OADJ

Output voltage adjust range

Set-point voltage tolerance

Temperature variation

Line regulaltion

3.6

V

(2)

±0.5

±0.3

±5

±1

%V_o

mV

–40°C < T_A< 85°C

Over V_Irange

V_O

Load regulation

Over I_Orange

±5

mV

(2)

Total output variation

Includes set-point, line, load, –40°C ≤ T_A≤ 85°C

R_SET= 1.62 kΩ, V_O= 3.3 V

±1.5

%V_o

94%

93%

91%

90%

88%

86%

R_SET= 5.23 kΩ, V_O= 2.5 V

R_SET= 12.7 kΩ, V_O= 1.8 V

η

Efficiency

I_O= 30 A

R_SET= 19.6 kΩ, V_O= 1.5 V

R_SET= 35.7 kΩ, V_O= 1.2 V

R_SET= 63.4 kΩ, V_O= 1.0 V

R_SET= open, V_O= 0.7 V

83%

(1)

V_ORipple (peak-to-peak)

Overcurrent threshold

20-MHz bandwidth

10

mV_PP

A

I_LIM

t_tr

Reset, followed by auto-recovery

100

160

100

Recovery time

V_Oover/undershoot

Recovery time

µs

w/o TurboTrans

C_O= 660 μF, TypeC

ΔV_tr

t_trTT

mV

µs

2.5 A/µs load step

50 to 100% I_Omax

Transient response

w/ TurboTrans

C_O= 3300 μF, TypeC

R_TT= short

mV

ΔV_trTT

V_Oover/undershoot

45

I_IL

Track input current (pin 20)

Pin to GND

–130⁽³⁾

1

µA

dV_track/dt Track slew rate capability

C_O≤ C_O(max)

V/ms

V_Iincreasing, R_UVLO= OPEN

V_Idecreasing, R_UVLO= OPEN

Hysteresis, R_UVLO≤ 127 kΩ

4.3

4.2

1.0

4.45

Adjustable Under-voltage lockout

UVLO_ADJ

(pin 21)

4.0

V

Input high voltage (V_IH

)

Open⁽⁴⁾

0.6

V

Inhibit control (pin 21)

Input low voltage (V_IL)

-0.2

Input low current (I_IL), Pin 21 to GND

-125

µA

mA

kHz

V

I_in

Input standby current

Switching frequency

Inhibit (pin 21) to GND, Track (pin 20) open

35

(5)

f _s

Over V_Iand I_Oranges, SmartSync (pin 22) to GND

Synchronization frequency applied to pin 22

SYNC High-Level Input Voltage

600

(5)

f_SYNC

V_SYNCH

V_SYNCL

t_SYNC

240

400

3.9

5.5

0.8

Synchronization (SYNC)

control (pin 22)

SYNC Low-Level Input Voltage

V

SYNC Minimum Pulse Width

200

nSec

(1) For output voltages less than 1.2 V, the output ripple may increase (up to 2×) when operating at input voltages greater than (V_O× 12).

Adjusting the switching frequency using the SmartSync feature may increase or decrease this ratio. Please review the SmartSync

section of the Application Information for further guidance.

(2) The set-point voltage tolerance is affected by the tolerance and stability of R_SET. The stated limit is unconditionally met if R_SEThas a

tolerance of 1% with 100 ppm/C or better temperature stability.

(3) A low-leakage (<100 nA), open-drain device, such as MOSFET or voltage supervisor IC, is recommended to control pin 20. The

open-circuit voltage is less than 8 V_dc

.

(4) Do not place an external pull-up on this pin. If it is left open-circuit, the module operates when input power is applied. A small,

low-leakage (<100 nA) MOSFET is recommended for control. For additional information, see the related application section.

(5) The PTH08T250W is a two-phase power module. Each phase switches at 300kHz typical, 180° out of phase from one another. The

over-all switching frequency is 600 kHz typical. SmartSync controls the frequency of an individual phase.

4

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ELECTRICAL CHARACTERISTICS

PTH08T250W

(continued)

T_A= 25°C, V_I= 12 V, V_O= 3.3 V, C_I= 1000 µF, C_O= 660 µF, and I_O= I_Omax (unless otherwise stated)

PARAMETER

TEST CONDITIONS

PTH08T250W

UNIT

MIN

TYP

MAX

(6)

(7)

Nonceramic 1000

Ceramic

C_I

External input capacitance

µF

22

(8)

Capacitance Value

Nonceramic

Ceramic

660

8000

w/o TurboTrans

w/ TurboTrans

1000

Equivalent series resistance (non-ceramic)

Capacitance Value

3

mΩ

µF

C_O

External output capacitance

see table

(7) (9)

(9)

Capacitance × ESR product (C_O× ESR)

1000

2.79

10000

µF×mΩ

10⁶Hr

Per Telcordia SR-332, 50% stress,

T_A= 40°C, ground benign

MTBF

Reliability

(6) A 1000 µF electrolytic input capacitor is required for proper operation. When operating at an input voltage greater than 8V the minimum

required input capacitance may be reduced to 560μF. The input capacitor must be rated for a minimum of 600 mA rms of ripple current.

(7) 660 µF of external output capacitance is required for basic operation. Adding additional capacitance at the load further improves

transient response. See the Capacitor Application Information section and the TuboTrans Technology section for more guidance.

(8) This is the calculated maximum when not using TurboTrans™ technology. This value includes both ceramic and non-ceramic

capacitors. The minimum ESR requirement often results in a lower value of output capacitance. See the Capacitor Application

Information section for more guidance.

(9) When using TurboTrans™ technology, a minimum value of output capacitance is required for proper operation. Additionally, low ESR

capacitors are required for proper operation. See the TurboTrans Technology section for further guidance.

22

1

21

20

19

18

17

16

15

14

2

3

Texas

Instruments

4

5

PTH08T250W

6

7

8

9

10 11

12 13

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Table 1. TERMINAL FUNCTIONS

TERMINAL

DESCRIPTION

NAME

V_I

NO.

6,7,14,15 The positive input voltage power node to the module, which is referenced to common GND.

V_O

10,11

The regulated positive power output with respect to GND.

This is the common ground connection for the V_Iand V_Opower connections. It is also the 0 V_dcreference for

the control inputs.

GND

8,9,12,13

The Inhibit pin is an open-collector/drain, negative logic input that is referenced to GND. Applying a low level

ground signal to this input disables the module’s output and turns off the output voltage. When the Inhibit

control is active, the input current drawn by the regulator is significantly reduced. If the Inhibit pin is left

open-circuit, the module produces an output whenever a valid input source is applied.

Inhibit⁽¹⁾and

UVLO

21

18

This pin is also used for input undervoltage lockout (UVLO) programming. Connecting a resistor from this pin

to GND (pin 13) allows the ON threshold of the UVLO to be adjusted higher than the default value. For more

information, see the Application Information section.

A 0.05 W 1% resistor must be directly connected between this pin and pin4 (AGND) to set the output voltage

to a value higher than 0.7V. The temperature stability of the resistor should be 100 ppm/°C (or better). The

setpoint range for the output voltage is from 0.7V to 3.6V. If left open circuit, the output voltage defaults to its

lowest value. For further information, on output voltage adjustment see the related application note.

V_oAdjust

The specification table gives the preferred resistor values for a number of standard output voltages.

The sense input allows the regulation circuit to compensate for voltage drop between the module and the

load. The +Sense pin should always be connected to V_O, either at the load for optimal voltage accuracy, or at

the module (pin 11).

+ Sense

– Sense

17

16

The sense input allows the regulation circuit to compensate for voltage drop between the module and the

load. The –Sense pin should always be connected to GND, either at the load for optimal voltage accuracy, or

at the module (pin 13).

This is an analog control input that enables the output voltage to follow an external voltage. This pin becomes

active typically 25 ms after a valid input voltage has been applied, and allows direct control of the output

voltage from 0 V up to the nominal set-point voltage. Within this range the module's output voltage follows the

voltage at the Track pin on a volt-for-volt basis. When the control voltage is raised above this range, the

module regulates at its set-point voltage. The feature allows the output voltage to rise simultaneously with

other modules powered from the same input bus. If unused, this input should be connected to V_I.

Track

20

19

NOTE: Due to the undervoltage lockout feature, the output of the module cannot follow its own input voltage

during power up. For more information, see the related application note.

This input pin adjusts the transient response of the regulator. To activate the TurboTrans™ feature, a 1%,

50mW resistor, must be connected between this pin and pin 17 (+Sense) very close to the module. For a

given value of output capacitance, a reduction in peak output voltage deviation is achieved by utililizing this

feature. If unused, this pin must be left open-circuit. The resistance requirement can be selected from the

TurboTrans resistor table in the Application Information section. External capacitance must never be

connected to this pin unless the TurboTrans resistor value is a short, 0Ω.

TurboTrans™

This input pin sychronizes the switching frequency of the module to an external clock frequency. The

SmartSync feature can be used to sychronize the switching frequency of multiple modules, aiding EMI noise

suppression efforts. The external synchronization frequency must be present before a valid input voltage is

present, or before the release of inhibit control. If unused, this pin MUST be connected to GND. For more

information, please review the Application Information section.

SmartSync

CONFIG

22

1

When two modules are connected together to share load current one must be configured as the MASTER and

the other as the SLAVE. This pin is used to configure the module as either MASTER or SLAVE. To configure

the module as the MASTER, connect this pin to GND. To configure the module as the SLAVE, connect this

pin to V_I(pin 6). When not sharing current, this pin should be connected to GND.

This pin is used when connecting two modules together to share load current. When two modules are sharing

current the Share pin of both modules must be connected together. When not sharing current, this pin MUST

be left open (floating).

Share

Comp

AGND

CLKIO

2

3

4

5

This pin is used when connecting two modules together to share load current. When two modules are sharing

current the Comp pin of both modules must be connected together. When not sharing current, this pin MUST

be left open (floating).

This pin is the internal analog ground of the module. This pin provides the return path for the V_OAdjust resistor

(R_SET). When two modules are sharing current the AGND pin of both modules must be connected together.

Also, when two modules are connected, R_SETmust be connected only on the MASTER module.

This pin is used when connecting two modules together to share load current. When two modules are sharing

current the CLKIO pin of both modules must be connected together. When not sharing current, this pin MUST

be left open (floating).

(1) Denotes negative logic: Open = Normal operation, Ground = Function active

6

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TYPICAL CHARACTERISTICS⁽¹⁾⁽²⁾

CHARACTERISTIC DATA ( V_I= 12 V)

EFFICIENCY

vs

LOAD CURRENT

OUTPUT RIPPLE

vs

LOAD CURRENT

POWER DISSIPATION

vs

LOAD CURRENT

100

95

90

85

80

75

70

65

60

55

50

14

12

10

8

12

3.3

V

(V)

V

OUT

(V)

OUT

1.8

3.3

2.5

1.8

1.5

1.2

1.0

3.3

2.5

1.8

1.2

0.7

10

8

2.5

(V)

1.8

3.3

1.5

6

1.2

V

1.0

OUT

1.8

1.2

3.3

2.5

1.8

1.5

1.2

1.0

0.7

1.2

0.7

6

1.0

4

2

4

0.7

1.5

2

0

10

20

30

40

50

0

10

20

30

40

50

0

10

20

30

40

50

I

- Output Current - A

I

- Output Current - A

O

I

- Output Current - A

O

Figure 1.

Figure 2.

Figure 3.

AMBIENT TEMPERATURE

vs

AMBIENT TEMPERATURE

vs

LOAD CURRENT

90

80

90

80

70

400 LFM

200 LFM

400 LFM

200 LFM

60

50

40

60

50

40

V

= 1.2 V

O

V

= 3.3 V

O

100 LFM

Airflow

400 LFM

200 LFM

100 LFM

Nat conv

200 LFM

100 LFM

Nat conv

Natural

Convection

30

20

Natural

Convection

20

0

10

20

30

40

50

0

10

20

30

40

50

I

- Output Current - A

I

- Output Current - A

O

Figure 4.

Figure 5.

(1) The electrical characteristic data has been developed from actual products tested at 25C. This data is considered typical for the

converter. Applies to Figure 1, Figure 2, and Figure 3.

(2) The temperature derating curves represent the conditions at which internal components are at or below the manufacturer's maximum

operating temperatures. Derating limits apply to modules soldered directly to a 100 mm x 100 mm double-sided PCB with 2 oz. copper

and the direction of airflow from pin 10 to pin 22. For surface mount packages (AS and AZ suffix), multiple vias must be utilized. Please

refer to the mechanical specification for more information. Applies to Figure 4 and Figure 5.

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TYPICAL CHARACTERISTICS⁽¹⁾⁽²⁾

CHARACTERISTIC DATA ( V_I= 5 V)

EFFICIENCY

vs

LOAD CURRENT

OUTPUT RIPPLE

vs

LOAD CURRENT

POWER DISSIPATION

vs

LOAD CURRENT

100

3.3

10

9

12

10

V

(V)

V (V)

OUT

95

90

85

80

OUT

3.3

2.5

3.3

2.5

1.8

1.2

0.7

3.3

2.5

1.8

1.2

0.7

8

1.8

8

6

4

7

2.5

(V)

1.8

1.5

0.7

1.2

1.0

75

70

65

60

55

50

6

0.7

V

1.2

OUT

5

3.3

2.5

1.8

1.5

1.2

1.0

0.7

1.2

4

0.7

1.8

2

0

3

2

0

10

20

30

40

50

0

10

20

30

40

50

0

10

20

30

40

50

I

- Output Current - A

I

- Output Current - A

I - Output Current - A

O

Figure 6.

Figure 7.

Figure 8.

AMBIENT TEMPERATURE

vs

AMBIENT TEMPERATURE

vs

LOAD CURRENT

90

80

70

400 LFM

200 LFM

400 LFM

200 LFM

60

50

40

60

50

40

V

= 3.3 V

O

V

= 1.2 V

O

100 LFM

Airflow

400 LFM

Airflow

400 LFM

200 LFM

100 LFM

Nat conv

200 LFM

100 LFM

Nat conv

30

Natural

Convection

Natural

Convection

30

20

0

20

10

20

30

40

50

0

10

20

30

40

50

I

- Output Current - A

O

I

- Output Current - A

O

Figure 9.

Figure 10.

(1) The electrical characteristic data has been developed from actual products tested at 25C. This data is considered typical for the

converter. Applies to Figure 6, Figure 7, and Figure 8.

(2) The temperature derating curves represent the conditions at which internal components are at or below the manufacturer's maximum

operating temperatures. Derating limits apply to modules soldered directly to a 100 mm x 100 mm double-sided PCB with 2 oz. copper

and the direction of airflow from pin 10 to pin 22. For surface mount packages (AS and AZ suffix), multiple vias must be utilized. Please

refer to the mechanical specification for more information. Applies to Figure 9 and Figure 10.

8

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APPLICATION INFORMATION

ADJUSTING THE OUTPUT VOLTAGE

The V_oAdjust control sets the output voltage of the PTH08T250W. The adjustment range of the PTH08T250W is

0.7 V to 3.6 V. The adjustment method requires the addition of a single external resistor, R_SET, that must be

connected directly between pins V_oAdjust (pin 18) and AGND (pin 4). Table 2 gives the standard value of the

external resistor for a number of standard voltages, along with the actual output voltage that this resistance value

provides.

For other output voltages, the value of the required resistor can either be calculated using the following formula,

or simply selected from the range of values given in Table 3. Figure 11 shows the placement of the required

resistor.

æ

ç

è

ö

÷

ø

0.7

R

= 30.1(kW)´

- 6.49 (kW)

SET

V - 0.7

O

(1)

Table 2. Standard Values of R_SETfor Standard Output Voltages

V_O(Standard) (V)

R_SET(Standard Value) (kΩ)

V_O(Actual) (V)

3.298

3.3

2.5

2.0

1.8

1.5

1.2

1.62

5.23

9.76

12.7

19.6

35.7

63.4

Open

2.498

1.997

1.798

1.508

1.199

(1)

1.0

1.001

(1)

0.7

0.700

(1) The maximum input voltage is duty cycle limited to (V_O× 12) or 14 volts, whichever is less. The

maximum allowable input voltage is a function of switching frequency, and may increase or decrease

when the SmartSync feature is utilized. Please review the SmartSync section of the Application

Information for further guidance.

+Sense 17

+Sense

10

11

V

O

PTH08T250W

V

O

-Sense 16

Adj

V

GND GND GND GND

12 13

AGND

O

+

8

9

4

18

C

O

R

SET

1%

0.05 W

-Sense

GND

UDG-07049

(1) R_SET: Use a 0.05 W resistor with a tolerance of 1% and temperature stability of 100 ppm/°C (or better). Connect the

resistor directly between pins 18 and 4, as close to the regulator as possible, using dedicated PCB traces.

(2) Never connect capacitors from V_OAdjust to either + Sense, GND, or V_O. Any capacitance added to the V_OAdjust pin

affects the stability of the regulator.

Figure 11. V_OAdjust Resistor Placement

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Table 3. Output Voltage Set-Point Resistor Values

V_ORequired (V)

R_SET(kΩ)

Open

412

V_ORequired (V)

2.10

R_SET(kΩ)

8.66

7.50

6.65

5.90

5.23

4.64

4.02

3.57

3.09

2.67

2.26

1.96

1.62

1.30

1.02

0.768

(1)

0.70

(1)

0.75

2.20

(1)

0.80

205

2.30

(1)

0.85

133

2.40

(1)

0.90

97.6

78.7

63.4

46.4

35.7

28.7

23.7

19.6

16.9

14.7

12.7

11.0

9.76

2.50

(1)

0.95

2.60

(1)

1.00

2.70

(1)

1.10

2.80

1.20

1.30

1.40

1.50

1.60

1.70

1.80

1.90

2.00

2.90

3.00

3.10

3.20

3.30

3.40

3.50

3.60

(1) For output voltages less than 1.2 V, the output ripple may increase (up to 2×) when operating at input

voltages greater than (V_O× 12). Adjusting the switching frequency using the SmartSync feature may

increase or decrease this ratio. Please review the SmartSync section of the Application Information for

further guidance.

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CAPACITOR RECOMMENDATIONS FOR THE PTH08T250W POWER MODULE

Capacitor Technologies

Electrolytic Capacitors

When using electrolytic capacitors, high quality, computer-grade electrolytic capacitors are recommended.

Aluminum electrolytic capacitors provide adequate decoupling over the frequency range, 2 kHz to 150 kHz,

and are suitable when ambient temperatures are above -20°C. For operation below -20°C, tantalum,

ceramic, or OS-CON type capacitors are required.

Ceramic Capacitors

Above 150 kHz the performance of aluminum electrolytic capacitors is less effective. Multilayer ceramic

capacitors have very low ESR and a resonant frequency higher than the bandwidth of the regulator. They

can be used to reduce the reflected ripple current at the input as well as improve the transient response of

the output.

Tantalum, Polymer-Tantalum Capacitors

Tantalum type capacitors may only used on the output bus, and are recommended for applications where the

ambient operating temperature is less than 0°C. The AVX TPS series and Kemet capacitor series are

suggested over many other tantalum types due to their lower ESR, higher rated surge, power dissipation,

and ripple current capability. Tantalum capacitors that have no stated ESR or surge current rating are not

recommended for power applications.

Input Capacitor (Required)

The PTH08T250W requires a minimum input capacitance of 1000μF. The ripple current rating of the input

capacitor must be at least 600mArms. An optional 22μF X5R/X7R ceramic capacitor is recommended to reduce

RMS ripple current.

Input Capacitor Information

The size and value of the input capacitor is determined by the converter’s transient performance capability. This

minimum value assumes that the converter is supplied with a responsive, low inductance input source. This

source should have ample capacitive decoupling, and be distributed to the converter via PCB power and ground

planes.

Ceramic capacitors should be located as close as possible to the module's input pins, within 0.5 inch (1,3 cm).

Adding ceramic capacitance is necessary to reduce the high-frequency ripple voltage at the module's input. This

reduces the magnitude of the ripple current through the electroytic capacitor, as well as the amount of ripple

current reflected back to the input source. Additional ceramic capacitors can be added to further reduce the RMS

ripple current requirement for the electrolytic capacitor.

The main considerations when selecting input capacitors are the RMS ripple current rating, temperature stability,

and less than 100 mΩ of equivalent series resistance (ESR).

Regular tantalum capacitors are not recommended for the input bus. These capacitors require a recommended

minimum voltage rating of 2 × (maximum dc voltage + ac ripple). This is standard practice to ensure reliability. No

tantalum capacitors were found with a sufficient voltage rating to meet this requirement.

When the operating temperature is below 0°C, the ESR of aluminum electrolytic capacitors increases. For these

applications, OS-CON, poly-aluminum, and polymer-tantalum types should be considered.

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Output Capacitor (Required)

The PTH08T250W requires a minimum output capacitance of 660μF of polymer-aluminum, tantulum, or

polymer-tantalum type.

The required capacitance above the minimum is determined by actual transient deviation requirements. See the

TurboTrans Technology application section within this document for specific capacitance selection.

Output Capacitor Information

When selecting output capacitors, the main considerations are capacitor type, temperature stability, and ESR.

When using the TurboTrans feature, the capacitance × ESR product should also be considered (see the

following section).

Ceramic output capacitors added for high-frequency bypassing should be located as close as possible to the

load to be effective. Ceramic capacitor values below 10μF should not be included when calculating the total

output capacitance value.

When the operating temperature is below 0°C, the ESR of aluminum electrolytic capacitors increases. For these

applications, OS-CON, poly-aluminum, and polymer-tantalum types should be considered.

TurboTrans Output Capacitance

TurboTrans allows the designer to optimize the output capacitance according to the system transient design

requirement. High quality, ultra-low ESR capacitors are required to maximize TurboTrans effectiveness. When

using TurboTrans, the capacitor's capacitance (μF) × ESR (mΩ) product determines its capacitor type; Type A,

B, or C. These three types are defined as follows:

Type A = (100 ≤ capacitance × ESR ≤ 1000) (e.g. ceramic)

Type B = (1000 < capacitance × ESR ≤ 5000) (e.g. polymer-tantalum)

Type C = (5000 < capacitance × ESR ≤ 10,000) (e.g. OS-CON)

When using more than one type of output capacitor, select the capacitor type that makes up the majority of your

total output capacitance. When calculating the C×ESR product, use the maximum ESR value from the capacitor

manufacturer's datasheet.

Working Examples:

A capacitor with a capacitance of 330μF and an ESR of 5mΩ, has a C×ESR product of 1650μFxmΩ (330μF ×

5mΩ). This is a Type B capacitor. A capacitor with a capacitance of 1000μF and an ESR of 8mΩ, has a C×ESR

product of 8000μFxmΩ (1000μF × 8mΩ). This is a Type C capacitor.

See the TurboTrans Technology application section within this document for specific capacitance selection.

Table 4 includes a preferred list of capacitors by type and vendor. See the Output Bus / TurboTrans column.

Non-TurboTrans Output Capacitance

If the TurboTrans feature is not used, minimum ESR and maximum capacitor limits must be followed. System

stability may be effected and increased output capacitance may be required without TurboTrans.

When using the PTH08T250W, observe the minimum ESR of the entire output capacitor bank. The minimum

ESR limit of the output capacitor bank is 7mΩ. A list of preferred low-ESR type capacitors, are identified in

Table 4.

When using the PTH08T250W without the TurboTrans feature, the maximum amount of capacitance is tbdμF of

ceramic type. Large amounts of capacitance may reduce system stability.

Utilizing the TurboTrans feature improves system stability, improves transient response, and reduces the

amount of output capacitance required to meet system transient design requirements.

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Designing for Fast Load Transients

The transient response of the dc/dc converter has been characterized using a load transient with a di/dt of

2.5A/µs. The typical voltage deviation for this load transient is given in the Electrical Characteristics table using

the minimum required value of output capacitance. As the di/dt of a transient is increased, the response of a

converter’s regulation circuit ultimately depends on its output capacitor decoupling network. This is an inherent

limitation with any dc/dc converter once the speed of the transient exceeds its bandwidth capability.

If the target application specifies a higher di/dt or lower voltage deviation, the requirement can only be met with

additional low ESR ceramic capacitor decoupling. Generally, with load steps greater than 100A/μs, adding

multiple 10μF ceramic capacitors plus 10×1μF, and numerous high frequency ceramics (≤0.1μF) is all that is

required to soften the transient higher frequency edges. The PCB location of these capacitors in relation to the

load is critical. DSP, FPGA and ASIC vendors identify types, location and amount of capacitance required for

optimum performance. Low impedance buses, unbroken PCB copper planes, and components located as close

as possible to the high frequency devices are essential for optimizing transient performance.

Capacitor Table

Table 4 identifies the characteristics of acceptable capacitors from a number of vendors. The recommended

number of capacitors required at both the input and output buses is identified for each capacitor.

This is not an extensive capacitor list. Capacitors from other vendors are available with comparable

specifications. Those listed are for guidance. The RMS ripple current rating and ESR (at 100 kHz) are critical

parameters necessary to ensure both optimum regulator performance and long capacitor life.

Table 4. Input/Output Capacitors⁽¹⁾

Capacitor Characteristics

Quantity

Output Bus

Max

Max.

Ripple

Capacitor Vendor,

Type Series (Style)

Working

Voltage

(V)

ESR at

Value

(µF)

Current

at 85°C

(Irms)

(mA)

Physical

Size (mm)

Input

Bus

No

100

kHz

(Ω)

Vendor Part No.

TurboTrans

Turbo

Trans

(Cap Type)⁽²⁾

Panasonic

25

1000

1800

2200

1000

0.043

0.029

0.028

0.060

1690

2205

2490

1100

16 × 15

16 × 20

1

≥ 2⁽³⁾

≥ 1⁽³⁾

≥ 2⁽⁵⁾

N/R⁽⁴⁾

EEUFC1E102S

FC (Radial)

EEUFC1E182

EEVFC1E222N

EEVFK1V102Q

FC (SMD)

18 × 21,5

12,5×13,5

FK (SMD)

United Chemi-Con

PTB Poly-Tant (SMD)

LXZ, Aluminum (Radial)

PS, Poly-Alum (Radial)

PXA, Poly-Alum (SMD)

PS, Poly-Alum (Radial)

PXA, Poly-Alum (Radial)

6.3

25

330

680

330

680

0.025

0.068

0.014

0.010

2600

1050

5060

5050

5500

7,3x4,3x 2,8 N/R⁽⁶⁾2 - 4⁽³⁾

(C) ≥ 2⁽²⁾

N/R⁽⁴⁾

(B) ≥ 2⁽²⁾

(C) ≥ 1⁽²⁾

4PTB337MD6TER

LXZ25VB681M10X20LL

16PS330MJ12

10 × 16

10 × 12,5

10 × 12,2

10 × 12,5

10 × 12,2

1

2

1 - 3⁽³⁾

2 - 3

1 - 2

16

2

PXA16VC331MJ12TP

6PS680MJ12

6.3

N/R⁽⁶⁾

PXA6.3VC681MJ12TP

(1) Capacitor Supplier Verification

Please verify availability of capacitors identified in this table. Capacitor suppliers may recommend alternative part numbers because of

limited availability or obsolete products. In some instances, the capacitor product life cycle may be in decline and have short-term

consideration for obsolescence.

RoHS, Lead-free and Material Details

See the capacitor suppliers regarding material composition, RoHS status, lead-free status, and manufacturing process requirements.

Component designators or part number deviations can occur when material composition or soldering requirements are updated.

(2) Required capacitors with TurboTrans. See the TransTrans Application information for Capacitor Selection

Capacitor Type Groups by ESR (Equivalent Series Resistance) :

a. Type A = (100 < capacitance × ESR ≤ 1000)

b. Type B = (1,000 < capacitance × ESR ≤ 5,000)

c. Type C = (5,000 < capacitance × ESR ≤ 10,000)

(3) Total bulk nonceramic capacitors on the output bus with ESR of ≥ 15mΩ to ≤ 30mΩ requires an additional ≥ 200 μF of ceramic

capacitor.

(4) Aluminum Electrolytic capacitor not recommended for the TurboTrans due to higher ESR × capacitance products. Aluminum and higher

ESR capacitors can be used in conjunction with lower ESR capacitance.

(5) Output bulk capacitor's maximum ESR is ≥ 30 mΩ. Additional ceramic capacitance of ≥ 200 μF is required.

(6) N/R – Not recommended. The voltage rating does not meet the minimum operating limits.

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Table 4. Input/Output Capacitors (continued)

Capacitor Characteristics

Quantity

Output Bus

Max

Ripple

Current

at 85°C

(Irms)

(mA)

Max.

ESR at

100

kHz

(Ω)

Capacitor Vendor,

Type Series (Style)

Working

Voltage

(V)

Value

(µF)

Physical

Size (mm)

Input

Bus

No

Vendor Part No.

TurboTrans

Turbo

Trans

(Cap Type)⁽²⁾

Nichicon, Aluminum

HD (Radial)

25

35

2.0

560

680

560

390

0.060

0.038

0.048

0.005

1060

1430

1360

4000

12,5 × 15

10 × 16

16 × 15

1

≥ 2⁽⁷⁾

N/R⁽⁹⁾

N/R⁽⁸⁾

UPM1E561MHH6

UHD1C681MHR

UPM1V561MHH6

EEFSE0J391R (V_O≤ 1.6V)⁽¹¹⁾

PM (Radial)

Panasonic, Poly-Alum

Sanyo

7,3×4,3×4,2 N/R⁽⁹⁾

(B) ≥ 2⁽¹⁰⁾

TPE, Poscap (SMD)

TPE Poscap(SMD)

TPD Poscap (SMD)

SA, OS-CON (Radial)

SP OS-CON ( Radial)

SEPC, OS-CON (Radial)

SVPA, OS-CON (SMD)

AVX Tantalum, Series 3

TPM Multianode

4

680

470

1000

470

330

820

680

470

1000

470

330

680

0.015

0.007

0.005

0.015

0.016

0.012

0.035

0.018

0.035

0.040

0.015

0.005

3900

4400

6100

9700

4500

4700

2400

3800

2405

2000

3800

7300

7,3 × 4,3

16 × 26

N/R⁽⁹⁾

1

1 - 3

1 - 2

1

(C) ≥ 1⁽¹⁰⁾

(B) ≥ 2⁽¹⁰⁾

(B) ≥ 1⁽¹⁰⁾

N/R⁽⁸⁾

(C) ≥ 2⁽¹⁰⁾

(B) ≥ 2⁽¹⁰⁾

(C) ≥ 1^(10)(7)6SVPC820M

N/R⁽⁸⁾

(C) ≥ 2^(10)(7)TPME687M006#0018

N/R⁽⁸⁾

4TPE680MF (V_O≤ 2.8V)⁽¹¹⁾

2R5TPE470M7 (V_O≤ 1.8V)⁽¹¹⁾

2R5TPD1000M5 (V_O≤1.8V)⁽¹¹⁾

16SA1000M

2.5

16

10

16

6.3

4

1 - 3

2 - 3

10 × 11,5

10 × 12,7

8 × 11,9

7,3×4,3×4,1 N/R⁽⁹⁾2 - 7⁽⁷⁾

7,3×4,3×4,1 N/R⁽⁹⁾2 - 3⁽⁷⁾

N/R⁽⁹⁾

10SP470M

2

16SVP330M

N/R⁽⁹⁾1 - 2⁽⁷⁾

TPSE477M010R0045

TPS Series III (SMD)

Kemet, Poly-Tantalum

T520 (SMD)

7,3 × 5,7

7,3×4,3×4

N/R⁽⁹⁾2 - 7⁽⁷⁾

N/R⁽⁹⁾

TPSV108K004R0035 (V_O≤2.2V)⁽¹¹⁾

6.3

4

T520X337M010AS

T530X337M010AS

2 - 3

1

(B) ≥ 2⁽¹⁰⁾

(B) ≥ 1⁽¹⁰⁾

T530 (SMD)

T530X687M004ASE005

(V_O≤3.5V)⁽¹¹⁾

T530 (SMD)

2.5

1000

0.005

7300

7,3×4,3×4

N/R⁽⁹⁾

1

(B) ≥ 1⁽¹⁰⁾

T530X108M2R5ASE005 (V_O≤2.0V)⁽¹¹⁾

Vishay-Sprague

594D, Tantalum (SMD)

94SA, Os-con (Radial)

94SVP Os-Con (SMD)

Kemet, Ceramic X5R

(SMD)

6.3

16

1000

330

10

0.030

0.015

0.017

0.002

2890

9740

4500

–

7,2×5,7×4,1 N/R⁽⁹⁾

1 - 6

1 - 3

N/R⁽⁸⁾

(C) ≥ 1⁽¹⁰⁾

(A)⁽¹⁰⁾

594D108X06R3R2TR2T

94SA108X0016HBP

94SVP827X06R3F12

C1210C106M4PAC

C1210C476K9PAC

GRM32ER60J107M

GRM32ER60J476M

GRM32ER61E226K

GRM32DR61C106K

C3225X5R0J107MT

C3225X5R0J476MT

C3225X5R1C106MT0

C3225X5R1C226MT

16 × 25

10 × 12,7

3225

1

16

2

1

2 - 3

16

≥ 1⁽¹²⁾

6.3

25

47

N/R⁽⁹⁾

1

Murata, Ceramic X5R

(SMD)

100

47

–

3225

22

16

10

1

TDK, Ceramic X5R

(SMD)

6.3

16

100

47

0.002

–

3225

N/R⁽⁹⁾

1

10

16

22

1

(7) Total bulk nonceramic capacitors on the output bus with ESR of ≥ 15mΩ to ≤ 30mΩ requires an additional ≥ 200 μF of ceramic

capacitor.

(8) Aluminum Electrolytic capacitor not recommended for the TurboTrans due to higher ESR × capacitance products. Aluminum and higher

ESR capacitors can be used in conjunction with lower ESR capacitance.

(9) N/R – Not recommended. The voltage rating does not meet the minimum operating limits.

(10) Required capacitors with TurboTrans. See the TransTrans Application information for Capacitor Selection

Capacitor Type Groups by ESR (Equivalent Series Resistance) :

a. Type A = (100 < capacitance × ESR ≤ 1000)

b. Type B = (1,000 < capacitance × ESR ≤ 5,000)

c. Type C = (5,000 < capacitance × ESR ≤ 10,000)

(11) The voltage rating of this capacitor only allows it to be used for output voltage that is equal to or less than 80% of the working voltage.

(12) Maximum ceramic capacitance on the output bus is ≤ tbd μF. Any combination of the ceramic capacitor values is limited to tbd μF for

non-TurboTrans applications. The total capacitance is limited to tbd μF which includes all ceramic and non-ceramic types.

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TurboTrans™ Technology

TurboTrans technology is a feature introduced in the T2 generation of the PTH/PTV family of power modules.

TurboTrans optimizes the transient response of the regulator with added external capacitance using a single

external resistor. Benefits of this technology include reduced output capacitance, minimized output voltage

deviation following a load transient, and enhanced stability when using ultra-low ESR output capacitors. The

amount of output capacitance required to meet a target output voltage deviation is reduced with TurboTrans

activated. Likewise, for a given amount of output capacitance, with TurboTrans engaged, the amplitude of the

voltage deviation following a load transient is reduced. Applications requiring tight transient voltage tolerances

and minimized capacitor footprint area benefits greatly from this technology.

TurboTrans™ Selection

Utilizing TurboTrans requires connecting a resistor, R_TT, between the +Sense pin (pin17) and the TurboTrans pin

(pin19). The value of the resistor directly corresponds to the amount of output capacitance required. All T2

products require a minimum value of output capacitance whether or not TurboTrans is utilized. For the

PTH08T250W, the minimum required capacitance is 1000μF. When using TurboTrans, capacitors with a

capacitance × ESR product below 10,000 μF×mΩ are required. (Multiply the capacitance (in μF) by the ESR (in

mΩ) to determine the capacitance × ESR product.) See the Capacitor Selection section of the datasheet for a

variety of capacitors that meet this criteria.

Figure 12 thru Figure 15 show the amount of output capacitance required to meet a desired transient voltage

deviation with and without TurboTrans for several capacitor types; TypeB (e.g. polymer-tantalum) and TypeC

(e.g. OS-CON). To calculate the proper value of R_TT, first determine your required transient voltage deviation

limits and magnitude of your transient load step. Next, determine what type of output capacitors to be used. (If

more than one type of output capacitor is used, select the capacitor type that makes up the majority of your total

output capacitance.) Knowing this information, use the chart in Figure 12 thru Figure 15 that corresponds to the

capacitor type selected. To use the chart, begin by dividing the maximum voltage deviation limit (in mV) by the

magnitude of your load step (in Amps). This gives a mV/A value. Find this value on the Y-axis of the appropriate

chart. Read across the graph to the 'With TurboTrans' plot. From this point, read down to the X-axis which lists

the minimum required capacitance, C_O, to meet that transient voltage deviation. The required R_TTresistor value

can then be calculated using the equation or selected from the TurboTrans table. The TurboTrans tables include

both the required output capacitance and the corresponding R_TTvalues to meet several values of transient

voltage deviation for 25%(12.5A), 50%(25A), and 75%(37.5A) output load steps.

The chart can also be used to determine the achievable transient voltage deviation for a given amount of output

capacitance. Selecting the amount of output capacitance along the X-axis, reading up to the 'With TurboTrans'

curve, and then over to the Y-axis, gives the transient voltage deviation limit for that value of output capacitance.

The required R_TTresistor value can be calculated using the equation or selected from the TurboTrans table.

As an example, let's look at a 12-V application requiring a 60 mV deviation during an 15A load transient. A

majority of 470μF, 10mΩ ouput capacitors are used. Use the 12 V, Type B capacitor chart, Figure 12. Dividing

60mV by 15A gives 4mV/A transient voltage deviation per amp of transient load step. Select 4mV/A on the

Y-axis and read across to the 'With TurboTrans' plot. Following this point down to the X-axis gives us a minimum

required output capacitance of approximately 1500μF. The required R_TTresistor value for 1500μF can then be

calculated or selected from Table 5. The required R_TTresistor is approximately 17.4kΩ.

To see the benefit of TurboTrans, follow the 4mV/A marking across to the 'Without TurboTrans' plot. Following

that point down shows that you would need a minimum of 7500μF of output capacitance to meet the same

transient deviation limit. This is the benefit of TurboTrans.

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PTH08T250W Type B Capacitors

12-V INPUT

5-V INPUT

8

7

8

7

6

Without TurboTrans

6

5

4

3

2

With TurboTrans

1

C - Capacitance - mF

Figure 12. Capacitor Type B,

1000 < C(μF)×ESR(mΩ) ≤ 5000 (e.g. Polymer-Tantalum)

Figure 13. Capacitor Type B,

1000 < C(μF)×ESR(mΩ) ≤ 5000 (e.g. Polymer-Tantalum)

Table 5. Type B TurboTrans C_OValues and Required R_TTSelection Table

Transient Voltage Deviation (mV)

12 Volt Input

5 Volt Input

25% load step

(12.5 A)

50% load step

(25 A)

75% load step

(37.5 A)

C_O

Minimum

R_TT

Required

C_O

Minimum

R_TT

Required

Required Output

Capacitance (μF)

TurboTrans

Resistor (kΩ)

Required Output

Capacitance (μF)

TurboTrans

Resistor (kΩ)

100

85

75

60

50

40

30

25

200

170

150

120

100

70

300

255

225

180

150

105

90

660

open

143

660

750

open

226

800

870

93.1

34.8

18.7

8.45

1.87

short

1050

1300

1750

2500

3100

46.4

24.9

11.3

3.48

0.649

1150

1450

1950

2800

4000

60

50

75

R_TTResistor Selection

The TurboTrans resistor value, R_TTcan be determined from the TurboTrans programming Equation 2.

1- C 3300

(

O

)

R

= 40´

(kW)

TT

5´ C 3300 -1

)

O

(

(2)

Where C_Ois the total output capacitance in μF. C_Ovalues greater than or equal to 3300 μF require R_TTto be a

short, 0Ω. (Equation 2 results in a negative value for R_TTwhen C_O> 3300 μF.)

To ensure stability, a minimum amount of output capacitance is required for a given R_TTresistor value. The value

of R_TTmust be calculated using the minimum required output capacitance determined from Figure 12 and

Figure 13.

16

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PTH08T250W Type C Capacitors

12-V INPUT

5-V INPUT

8

7

6

8

7

6

Without TurboTrans

5

4

5

4

3

2

With TurboTrans

1

C - Capacitance - mF

Figure 14. Capacitor Type C,

5000 < C(μF)×ESR(mΩ) ≤ 10,000(e.g. OS-CON)

Figure 15. Capacitor Type C,

5000 < C(μF)×ESR(mΩ) ≤ 10,000(e.g. OS-CON)

Table 6. Type C TurboTrans C_OValues and Required R_TTSelection Table

Transient Voltage Deviation (mV)

12 Volt Input

5 Volt Input

25% load

step

(12.5 A)

50% load

step

(25 A)

75% load

step

(37.5 A)

C_O

R_TT

Required

TurboTrans

Resistor (kΩ)

C_O

R_TT

Required

TurboTrans

Resistor (kΩ)

Minimum Required

Output

Capacitance (μF)

Minimum Required

Output

Capacitance (μF)

85

75

60

50

40

30

25

20

170

150

120

100

80

255

225

180

150

120

90

660

720

open

340

660

800

open

143

46.4

22.6

10.5

2.61

short

-

950

64.9

30.9

14.3

5.23

1.87

short

1050

1350

1800

2650

3850

-

1200

1600

2250

2800

6000

60

50

75

40

60

R_TTResistor Selection

The TurboTrans resistor value, R_TTcan be determined from the TurboTrans programming Equation 3.

1- C 3300

(

O

)

R

= 40´

(kW)

TT

5´ C 3300 -1

)

O

(

(3)

Where C_Ois the total output capacitance in μF. C_Ovalues greater than or equal to 3300 μF require R_TTto be a

short, 0Ω. (Equation results in negative value for R_TTwhen C_O3300 μF).

3

a

>

To ensure stability, a minimum amount of output capacitance is required for a given R_TTresistor value. The value

of R_TTmust be calculated using the minimum required output capacitance determined from Figure 14 and

Figure 15.

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TurboTrans

R_TT

7.87 kW

AutoTrack

TurboTrans

+Sense

V_O

+Sense

V_I

V_O

PTH08T250W

Inhibit/UVLO

+

-Sense

V_OAdj

L

O

A

D

C_O

2000 mF

Type B

+

SmartSync Config GND AGND

C_I

C_I2

1000 mF

(Required)

22 mF

R_SET

-Sense

GND

UDG-07101

Figure 16. Typical TurboTrans™ Application

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Soft-Start Power Up

The Auto-Track feature allows the power-up of multiple PTH/PTV modules to be directly controlled from the

Track pin. However in a stand-alone configuration, or when the Auto-Track feature is not being used, the Track

pin should be directly connected to the input voltage, V_I(see Figure 17).

V

I

(2 V/div)

20

Track

V

I

6

7

V

I

PTH08T250W

14

15

+

C

I

GND GND GND GND

12 13

V

O

8

9

(500 mV/div)

GND

I

(5 A/div)

UDG-07102

t − Time − 10 ms/div

Figure 17. Defeating the Auto-Track Function

Figure 18. Power-Up Waveform

When the Track pin is connected to the input voltage the Auto-Track function is permanently disengaged. This

allows the module to power up entirely under the control of its internal soft-start circuitry. When power up is

under soft-start control, the output voltage rises to the set-point at a quicker and more linear rate.

From the moment a valid input voltage is applied, the soft-start control introduces a short time delay (typically

10 ms–15 ms) before allowing the output voltage to rise.

The output then progressively rises to the module’s setpoint voltage. Figure 18 shows the soft-start power-up

characteristic of the PTH08T250W operating from a 5-V input bus and configured for a 1.2-V output. The

waveforms were measured with a 25-A constant current load and the Auto-Track feature disabled. The initial rise

in input current when the input voltage first starts to rise is the charge current drawn by the input capacitors.

Power-up is complete within 30 ms.

Differential Output Voltage Remote Sense

Differential remote sense improves the load regulation performance of the module by allowing it to compensate

for any IR voltage drop between its output and the load in either the positive or return path. An IR drop is caused

by the output current flowing through the small amount of pin and trace resistance. With the sense pins

connected, the difference between the voltage measured directly between the V_Oand GND pins, and that

measured at the Sense pins, is the amount of IR drop being compensated by the regulator. This should be

limited to a maximum of 0.3V.

If the remote sense feature is not used at the load, connect +Sense (pin 17) to V_O(pin11) and connect –Sense

(pin 16) to the module GND (pin 13).

The remote sense feature is not designed to compensate for the forward drop of nonlinear or frequency

dependent components that may be placed in series with the converter output. Examples include OR-ing

diodes, filter inductors, ferrite beads, and fuses. When these components are enclosed by the remote sense

connection they are effectively placed inside the regulation control loop, which can adversely affect the

stability of the regulator.

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On/Off Inhibit

For applications requiring output voltage on/off control, the PTH08T250W incorporates an Inhibit control pin. The

inhibit feature can be used wherever there is a requirement for the output voltage from the regulator to be turned

off. The power modules function normally when the Inhibit pin is left open-circuit, providing a regulated output

whenever a valid source voltage is connected to V_Iwith respect to GND.

Figure 19 shows the typical application of the inhibit function. Note the discrete transistor (Q1). The Inhibit input

has its own internal pull-up. An external pull-up resistor should never be used with the inhibit pin. The input is not

compatible with TTL logic devices. An open-collector (or open-drain) discrete transistor is recommended for

control.

Turning Q1 on applies a low voltage to the Inhibit control pin and disables the output of the module. If Q1 is then

turned off, the module executes a soft-start power-up sequence. A regulated output voltage is produced within 20

ms. Figure 20 shows the typical rise in both the output voltage and input current, following the turn-off of Q1. The

turn off of Q1 corresponds to the rise in the waveform, V_INH. The waveforms were measured with a 25-A constant

current load.

V

I

V

O

6

7

V

(500 mV/div)

I

14

15

PTH08T250W

(5 A/div)

+

C

I

21 Inhibit/UVLO

GND GND GND GND

12 13

1=Inhibit

GND

8

9

Q1

BSS 138

V

INH

UDG-07104

(2 V/div)

t − Time − 20 ms/div

Figure 20. Power-Up Response from Inhibit Control

Figure 19. On/Off Inhibit Control Circuit

Overcurrent Protection

For protection against load faults, all modules incorporate output overcurrent protection. Applying a load that

exceeds the regulator's overcurrent threshold causes the regulated output to shut down. Following shutdown, the

module periodically attempts to recover by initiating a soft-start power-up. This is described as a hiccup mode of

operation, whereby the module continues in a cycle of successive shutdown and power up until the load fault is

removed. During this period, the average current flowing into the fault is significantly reduced. Once the fault is

removed, the module automatically recovers and returns to normal operation.

Overtemperature Protection (OTP)

A thermal shutdown mechanism protects the module’s internal circuitry against excessively high temperatures. A

rise in the internal temperature may be the result of a drop in airflow, or a high ambient temperature. If the

internal temperature exceeds the OTP threshold, the module’s Inhibit control is internally pulled low. This turns

the output off. The output voltage drops as the external output capacitors are discharged by the load circuit. The

recovery is automatic, and begins with a soft-start power up. It occurs when the sensed temperature decreases

by about 10°C below the trip point.

The overtemperature protection is a last resort mechanism to prevent thermal stress to the regulator.

Operation at or close to the thermal shutdown temperature is not recommended and reduces the long-term

reliability of the module. Always operate the regulator within the specified safe operating area (SOA) limits for

the worst-case conditions of ambient temperature and airflow.

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Smart Sync

Smart Sync is a feature that allows multiple power modules to be synchronized to a common frequency. When

not used, this pin must be connect to GND. Driving the Smart Sync pins with an external oscillator set to the

desired frequency, synchronizes all connected modules to the selected frequency. The synchronization

frequency can be higher or lower than the nominal switching frequency of the modules within the range of

240 kHz to 400 kHz.

Synchronizing modules powered from the same bus eliminates beat frequencies reflected back to the input

supply, and also reduces EMI filtering requirements. Eliminating the low beat frequencies (usually<10kHz) allows

the EMI filter to be designed to attenuate only the synchronization frequency. Power modules can also be

synchronized out of phase to minimize ripple current and reduce input capacitance requirements.

The PTH08T250W requires that the external synchronization frequency be present before a valid input voltage is

present or before release of the inhibit control. Figure 21 shows a standard circuit with two modules syncronized

180° out of phase using a D flip-flop.

0°

Track

Sync

TurboTrans

+Sense

V = 5 V

I

V

O1

I

PTH08T250W

V

O

SN74LVC2G74

+

-Sense

+

V

CC

C

I1

GND AGND

V Adj

O

C

O1

CLK

D

PRE

Q

f

= 2 x f

MOD

CLK

R

SET1

GND

180°

GND

Q

Track

Sync

TurboTrans

+Sense

V

O2

V

I

PTH08T240W

V

O

+

-Sense

V Adj

C

I2

GND

+

O

C

O2

R

SET2

GND

UDG-07105

Figure 21. Typical Smart Sync Schematic

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Operating the PTH08T250W with a low duty cycle may increase the output voltage ripple. When operating at the

nominal switching frequency, input voltages greater than (V_O× 12) may cause the output voltage ripple to

increase (up to 2×).

When using Smart Sync, the minimum duty cycle varies as a function of output voltage and switching frequency.

Synchronizing to a higher frequency causes greater restrictions on the duty cycle range. For a given switching

frequency, Figure 22 shows the operating region where the output voltage ripple meets the electrical

specifications. Operation above a given curve may cause the output voltage ripple to increase (up to 2×). For

example, a module operating at 400 kHz and an output voltage of 1.2 V, the maximum input voltage that meets

the output voltage ripple specification is 11 V. Exceeding 11 V may cause in an increase in output voltage ripple.

As shown in Figure 22, operating below 6V allows operation down to the minimum output voltage over the entire

synchronization frequency range without affecting the output voltage ripple. See the Electrical Characteristics

table for the synchronization frequency range limits.

The maximum output current that a single module can deliver may also be affected by the sychronization

frequency. See Figure 23 below for load current derating when sychronizing at frequencies greater than 330 kHz.

First consult the temperature derating graphs in the Typical Characteristics section to determine the maximum

output current based on operating conditions. Any derating due to the SmartSync frequency is in addition to the

temperature derating.

RECOMMENDED INPUT VOLTAGE

vs

FREQUENCY AND OUTPUT VOLTAGE

MAXIMUM LOAD CURRENT

vs

SMARTSYNC FREQUENCY

15

14

13

12

11

10

100

98

96

94

92

90

400

350

88

86

9

8

300

f

(kHz)

SW

240

300

350

400

84

82

80

7

6

5

240 260 280 300 320 340 360 380 400

0.7 0.9

1.1 1.3

V

1.5 1.7

- Output Voltage - V

1.9 2.1 2.3 2.5

f

- SmartSync Frequency - kHz

SS

O

Figure 22.

Figure 23.

22

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Auto-Track™ Function

The Auto-Track function is unique to the PTH/PTV family, and is available with all POLA products. Auto-Track

was designed to simplify the amount of circuitry required to make the output voltage from each module power up

and power down in sequence. The sequencing of two or more supply voltages during power up is a common

requirement for complex mixed-signal applications that use dual-voltage VLSI ICs such as the TMS320™ DSP

family, microprocessors, and ASICs.

How Auto-Track™ Works

(1)

Auto-Track works by forcing the module output voltage to follow a voltage presented at the Track control pin

.

This control range is limited to between 0 V and the module set-point voltage. Once the track-pin voltage is

raised above the set-point voltage, the module output remains at its set-point ⁽²⁾. As an example, if the Track pin

of a 2.5-V regulator is at 1 V, the regulated output is 1 V. If the voltage at the Track pin rises to 3 V, the regulated

output does not go higher than 2.5 V.

When under Auto-Track control, the regulated output from the module follows the voltage at its Track pin on a

volt-for-volt basis. By connecting the Track pin of a number of these modules together, the output voltages follow

a common signal during power up and power down. The control signal can be an externally generated master

ramp waveform, or the output voltage from another power supply circuit ⁽³⁾. For convenience, the Track input

incorporates an internal RC-charge circuit. This operates off the module input voltage to produce a suitable rising

waveform at power up.

Typical Auto-Track Application

The basic implementation of Auto-Track allows for simultaneous voltage sequencing of a number of Auto-Track

compliant modules. Connecting the Track inputs of two or more modules forces their track input to follow the

same collective RC-ramp waveform, and allows their power-up sequence to be coordinated from a common

Track control signal. This can be an open-collector (or open-drain) device, such as a power-up reset voltage

supervisor IC. See U3 in Figure 24.

To coordinate a power-up sequence, the Track control must first be pulled to ground potential. This should be

done at or before input power is applied to the modules. The ground signal should be maintained for at least

20 ms after input power has been applied. This brief period gives the modules time to complete their internal

soft-start initialization ⁽⁴⁾, enabling them to produce an output voltage. A low-cost supply voltage supervisor IC,

with a built-in time delay, is an ideal component for automatically controlling the Track inputs at power up.

Figure 24 shows how the TL7712A supply voltage supervisor IC (U3) can be used to coordinate the sequenced

power up of PTH08T250W modules. The output of the TL7712A supervisor becomes active above an input

voltage of 3.6 V, enabling it to assert a ground signal to the common track control well before the input voltage

has reached the module's undervoltage lockout threshold. The ground signal is maintained until approximately 28

ms after the input voltage has risen above U3's voltage threshold, which is 4.3 V. The 28-ms time period is

controlled by the capacitor C_T. The value of 2.2 µF provides sufficient time delay for the modules to complete

their internal soft-start initialization. The output voltage of each module remains at zero until the track control

voltage is allowed to rise. When U3 removes the ground signal, the track control voltage automatically rises. This

causes the output voltage of each module to rise simultaneously with the other modules, until each reaches its

respective set-point voltage.

Figure 25 shows the output voltage waveforms after input voltage is applied to the circuit. The waveforms, V_O1

and V_O2, represent the output voltages from the two power modules, U1 (3.3 V) and U2 (1.8 V), respectively.

V_TRK, V_O1, and V_O2 are shown rising together to produce the desired simultaneous power-up characteristic.

The same circuit also provides a power-down sequence. When the input voltage falls below U3's voltage

threshold, the ground signal is re-applied to the common track control. This pulls the track inputs to zero volts,

forcing the output of each module to follow, as shown in Figure 26. Power down is normally complete before the

input voltage has fallen below the modules' undervoltage lockout. This is an important constraint. Once the

modules recognize that an input voltage is no longer present, their outputs can no longer follow the voltage

applied at their track input. During a power-down sequence, the fall in the output voltage from the modules is

limited by the Auto-Track slew rate capability.

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Notes on Use of Auto-Track™

1. The Track pin voltage must be allowed to rise above the module set-point voltage before the module

regulates at its adjusted set-point voltage.

2. The Auto-Track function tracks almost any voltage ramp during power up, and is compatible with ramp

speeds of up to 1 V/ms.

3. The absolute maximum voltage that may be applied to the Track pin is the input voltage V_I.

4. The module cannot follow a voltage at its track control input until it has completed its soft-start initialization.

This takes about 20 ms from the time that a valid voltage has been applied to its input. During this period, it

is recommended that the Track pin be held at ground potential.

5. The Auto-Track function is disabled by connecting the Track pin to the input voltage (V_I). When Auto-Track is

disabled, the output voltage rises according to its softstart rate after input power has been applied.

6. The Auto-Track pin should never be used to regulate the module's output voltage for long-term, steady-state

operation.

R

V

TT1

I

12 V

AutoTrack

TurboTrans

+Sense

V

I

V

O

V

U1

PTH08T210W

O1

8

3.3 V

V

O

V

CC

+

C

7

2

SENSE

I1

-Sense

C

O1

RESET

5

RESIN

V Adj

O

GND GND GND GND

U3

TL7712A

R

RESET

R

SET1

10 kW

1

3

REF

CT

RESET

GND

6

GND

4

C

T

REF

R

TT2

0.1 mF

2.2 mF

AutoTrack

TurboTrans

+Sense

V

I

V

O

V

U2

PTH08T250W

O2

1.8 V

V

O

+

-Sense

C

O2

C

I2

V Adj

O

GND GND GND GND AGND

R

SET2

GND

UDG-07106

Figure 24. Sequenced Power Up and Power Down Using Auto-Track

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V

(1 V/div)

TRK

V

(1 V/div)

TRK

V

1 (1 V/div)

O

V 1 (1 V/div)

O

V

2 (1 V/div)

O

V

2 (1 V/div)

O

t − Time − 20 ms/div

t − Time − 400 ms/div

Figure 25. Simultaneous Power Up

With Auto-Track Control

Figure 26. Simultaneous Power Down

With Auto-Track Control

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ADJUSTING THE UNDERVOLTAGE LOCKOUT (UVLO)

The PTH08T250W power modules incorporate an input undervoltage lockout (UVLO). The UVLO feature

prevents the operation of the module until there is sufficient input voltage to produce a valid output voltage. This

enables the module to provide a clean, monotonic powerup for the load circuit, and also limits the magnitude of

current drawn from the regulator’s input source during the power-up sequence.

The UVLO characteristic is defined by the ON threshold (V_THD) voltage. Below the ON threshold, the Inhibit

control is overridden, and the module does not produce an output. The hysteresis voltage, which is the difference

between the ON and OFF threshold voltages, is set at 500 mV. The hysteresis prevents start-up oscillations,

which can occur if the input voltage droops slightly when the module begins drawing current from the input

source.

The UVLO feature of the PTH08T250W module allows for limited adjustment of the ON threshold voltage. The

adjustment is made via the Inhbit/UVLO Prog control pin (pin 11) using a single resistor (see Figure 27). When

pin 11 is left open circuit, the ON threshold voltage is internally set to its default value, which is 4.3 volts. The ON

threshold might need to be raised if the module is powered from a tightly regulated 12-V bus. Adjusting the

threshold prevents the module from operating if the input bus fails to completely rise to its specified regulation

voltage.

Equation 4 determines the value of R_UVLOrequired to adjust V_THDto a new value. The default value is 4.3 V, and

it may only be adjusted to a higher value.

230

R

=

(kW)

UVLO

V - 4.6

I

(4)

Table 7 lists the standard resistor values for R_UVLOfor different values of the on-threshold (V_THD) voltage.

Table 7. Standard R_UVLOvalues for Various V_THDvalues

V_THD(V)

5.5

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

10.5

11.0

R_UVLO(kΩ)

255

165

121

95.3

78.7

68.1

59.0

52.3

46.4

42.2

39.2

35.7

V

I

6

7

V

I

14

15

PTH08T250W

+

C

I

21 Inhibit/UVLO

GND GND GND GND

12 13

8

9

R

UVLO

GND

UDG-07103

Figure 27. Undervoltage Lockout Adjustment Resistor Placement

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CURRENT SHARING

The PTH08T250W module is capable of being configured in parallel with another PTH08T250W module to share

load current. To parallel the two modules, it is necessary to configure one module as the Master and one module

as the Slave. To configure a module as the Master, connect the CONFIG pin (pin 1) to GND. The CONFIG pin of

the Slave must be connected to V_I. In order to share current, pins 2 thru 5 of both the Master and Slave must be

connected between the two modules. See Figure 33 for the recommended layout of pins 2 thru 5. The module

that is configured as the MASTER is used to control all of the functions of the two modules including Inhibit

ON/OFF control, AutoTrack sequencing, TurboTrans, SmartSync, +/- Remote Sense, and Output Voltage Adjust.

See the current sharing diagram in Figure 28 for connections. The MASTER and the SLAVE must be powered

from the same input voltage supply.

See Figure 28 and Table 8 for a diagram and connection description of each pin when two PTH08T250W

modules are being used in a MASTER/SLAVE configuration.

CURRENT SHARING DIAGRAM

R

TT

20

19

V

I

Track

TT

+Sense

6

7

V

I

+Sense 17

V

O

10

11

V

O

14

15

PTH08T250W

(Master)

O

+

-Sense 16

C

21 INH/UVLO

22 SmartSync

I1

L

O

A

D

1000 mF

V Adj

O

GND GND GND GND Config Share Comp CLKIO AGND

12 13 1 2 3 5 4

8

9

18

+

R

SET

C

O1

-Sense

GND

1%

0.05 W

660 mF

GND

20

Track

1

2

3

5

4

19

6

7

Config Share Comp CLKIO AGND

TT

V

I

+Sense 17

14

15

10

11

V

O

PTH08T250W

(Slave)

O

21 INH/UVLO

22 SmartSync

C

I2

+

-Sense 16

1000 mF

C

O2

660 mF

+

V Adj

GND GND GND GND

12 13

O

8

9

18

UDG-07050

Figure 28. Typical Current Sharing Diagram

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Table 8. Required Connections for Current Sharing⁽¹⁾

TERMINAL

MASTER

SLAVE

NAME

V_I

NO.

6,7,14,15 Connect to the Input Bus.

10,11 Connect to the Output Bus.

8,9,12,13 Connect to Common Power GND.

Connect to the Input Bus.

V_O

Connect to the Output Bus.

GND

Connect to Common Power GND.

Inhibit and

UVLO

Use for Inhibit control & UVLO adjustments. If

unused leave open-circuit.

21

18

17

No Connection. Leave open-circuit.

Use to set the output voltage. Connect R_SET

resistor between this pin and AGND (pin 4).

V_oAdjust

+Sense

Connect to the output voltage either at the load or

at the module (pin 11).

Connect to the output GND either at the load or at

the module (pin 13).

–Sense

16

20

19

No Connection. Leave open-circuit.

Track

Connect to Track control or to V_I(pin 15).

Connect TurboTrans resistor, R_TT,between this pin

and +Sense (pin 17).

TurboTrans™

Connect to an external clock. If unused connect to

GND.

SmartSync

22

Connect to Common Power GND.

(2)

CONFIG

Share

1

2

3

4

5

Connect to GND.

Connect to the Input Bus.

Connect to pin 2 of Master.

Connect to pin 3 of Master.

Connect to pin 4 of Master.

Connect to pin 5 of Master.

(2)

Connect to pin 2 of Slave.

(2)

Comp

Connect to pin 3 of Slave.

(3)

AGND

CLKIO

Connect to pin 4 of Slave.

(2)

Connect to pin 5 of Slave.

(1) For more details on the pin descriptions, please refer to the 'Terminal Functions' described in Table 1

(2) See Layer A in Figure 33 for recommended layout

(3) See Layer B in Figure 33 for recommended layout

Current Sharing and TurboTrans™

When using TurboTrans while paralleling two modules, the TurboTrans resistor, R_TT, must be connected from the

TurboTrans pin (pin 19) of the Master module to the +Sense pin (pin 17) of the Master module. When paralleling

modules the procedure to calculate the proper value of output capacitance and R_TTis similar to that explained in

the TurboTrans Selection section, however the values must be calculated for a single module. Therefore, the

total output current load step must be halved before determining the required output capacitance and the R_TT

value as explained in the TurboTrans Selection section. The value of output capacitance calculated is the

minimum required output capacitance per module and the value of R_TTmust be calculated using this value of

output capacitance. The TurboTrans pin of the Slave module must be left open.

As an example, let's look at a 12-V application requiring a 60 mV deviation during an 30 A load transient. A

majority of 470 μF, 10 mΩ output capacitors are used. Use the 12 V, Type B capacitor chart, Figure 12. First,

halving the load transient gives 15 A. Dividing 60 mV by 15 A gives 4 mV/A transient voltage deviation per amp

of transient load step. Select 4 mV/A on the Y-axis and read across to the 'With TurboTrans' plot. Following this

point down to the X-axis gives us a minimum required output capacitance of approximately 1500 μF. This is the

minimum required output capacitance per module. Hence, the total minimum output capacitance would be

2x1500 μF = 3000 μF. The required R_TTresistor value for 1500 μF can then be calculated or selected from

Table 5. The required R_TTresistor is approximately 17.4 kΩ.

Current Sharing Thermal Derating Curves

The temperature derating curves in Figure 29 through Figure 32 represent the conditions at which internal

components are at or below the manufacturer's maximum operating temperatures. Derating limits apply to two

PTH08T250W modules soldered directly to a 100 mm x 200 mm double-sided PCB with 2 oz. copper and the

direction of airflow from pins 10 to pins 22. For surface mount packages (AS and AZ suffix), multiple vias must

be utilized. Please refer to the mechanical specification for more information.

28

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AMBIENT TEMPERATURE

vs

AMBIENT TEMPERATURE

vs

OUTPUT CURRENT

90

80

90

80

70

400 LFM

200 LFM

60

50

40

60

50

40

V = 12 V

I

V

= 3.3 V

V = 1.2 V

O

200 LFM

100 LFM

O

Airflow

400 LFM

Airflow

400 LFM

100 LFM

200 LFM

100 LFM

Nat conv

200 LFM

100 LFM

Nat conv

Natural

Convection

30

20

Natural

Convection

20

0

20

40

60

80

100

0

20

40

60

80

100

I

- Output Current - A

I

- Output Current - A

O

Figure 29.

Figure 30.

AMBIENT TEMPERATURE

vs

AMBIENT TEMPERATURE

vs

OUTPUT CURRENT

90

80

90

80

70

400 LFM

200 LFM

60

50

40

60

50

40

V = 5 V

I

200 LFM

I

V

= 3.3 V

V = 1.2 V

O

100 LFM

Airflow

400 LFM

Airflow

400 LFM

100 LFM

200 LFM

100 LFM

Nat conv

200 LFM

100 LFM

Nat conv

Natural

30

20

Convection

Natural

Convection

20

0

20

40

60

80

100

0

20

40

60

80

100

I

- Output Current - A

I

- Output Current - A

O

Figure 31.

Figure 32.

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Current Sharing Layout

In current sharing applications the V_Ipins of both modules must be connected to the same input bus. The V_O

pins of both modules are connected together to power the load. The GND pins of both modules are connected

via the GND plane. Four other inter-connection pins are connected between the modules. Figure 33 shows the

required layout of the inter-connection pins for two modules configured to share current. Notice that the Share

(pin 2) connection is routed between the Comp (pin 3) and CLKIO (pin 5) connections. AGND (pin 4) should be

connected as a thicker trace on an adjacent layer, running parallel to pins 2, 3 and 5. AGND must not be

connected to the GND plane.

1

LAYER A

MASTER

SLAVE

AGND

1

LAYER B

MASTER

SLAVE

UDG-07107

Figure 33. Recommended Layout of Inter-Connection Pins Between Two Current Sharing Modules

Prebias Startup Capability

A prebias startup condition occurs as a result of an external voltage being present at the output of a power

module prior to its output becoming active. This often occurs in complex digital systems when current from

another power source is backfed through a dual-supply logic component, such as an FPGA or ASIC. Another

path might be via clamp diodes as part of a dual-supply power-up sequencing arrangement. A prebias can cause

problems with power modules that incorporate synchronous rectifiers. This is because under most operating

conditions, these types of modules can sink as well as source output current.

The PTH family of power modules incorporate synchronous rectifiers, but does not sink current during startup⁽¹⁾,

or whenever the Inhibit pin is held low. However, to ensure satisfactory operation of this function, certain

conditions must be maintained⁽²⁾. Figure 35 shows an application demonstrating the prebias startup capability.

The startup waveforms are shown in Figure 34. Note that the output current (I_O) is negligible until the output

voltage rises above the voltage backfed through the intrinsic diodes.

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The prebias start-up feature is not compatible with Auto-Track. When the module is under Auto-Track control, it

sinks current if the output voltage is below that of a back-feeding source. To ensure a pre-bias hold-off one of

two approaches must be followed when input power is applied to the module. The Auto-Track function must

either be disabled⁽³⁾, or the module’s output held off (for at least 50 ms) using the Inhibit pin. Either approach

ensures that the Track pin voltage is above the set-point voltage at start up.

1. Startup includes the short delay (approximately 10 ms) prior to the output voltage rising, followed by the rise

of the output voltage under the module’s internal soft-start control. Startup is complete when the output

voltage has risen to either the set-point voltage or the voltage at the Track pin, whichever is lowest.

2. To ensure that the regulator does not sink current when power is first applied (even with a ground signal

applied to the Inhibit control pin), the input voltage must always be greater than the output voltage throughout

the power-up and power-down sequence.

3. The Auto-Track function can be disabled at power up by immediately applying a voltage to the module’s

Track pin that is greater than its set-point voltage. This can be easily accomplished by connecting the Track

pin to V_I.

V_IN(1 V/div)

V_O(1 V/div)

I_O(2 A/div)

t - Time - 4 ms/div

Figure 34. Prebias Startup Waveforms

3.3 V

Track

+Sense

V

V_I= 5 V

V_o= 2.5 V

I_o

V

PTH08T220W

I

O

Inhibit GND Vadj

-Sense

VCCIO

VCORE

+

C_O

+

R

C_I

SET

2.37 kW

ASIC

Figure 35. Application Circuit Demonstrating Prebias Startup

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Tape & Reel and Tray Drawings

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PACKAGE OPTION ADDENDUM

www.ti.com

24-Sep-2007

PACKAGING INFORMATION

Orderable Device

PTH08T250WAD

PTH08T250WAS

PTH08T250WAST

PTH08T250WAZ

PTH08T250WAZT

Status ⁽¹⁾

ACTIVE

Package Package

Pins Package Eco Plan ⁽²⁾Lead/Ball Finish MSL Peak Temp ⁽³⁾

Qty

Type

Drawing

DIP MOD

ULE

ECT

22

25

TBD

Call TI

DIP MOD

ULE

ECU

BCU

25

DIP MOD

ULE

200

25

DIP MOD

ULE

DIP MOD

ULE

200

⁽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.

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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

IMPORTANT NOTICE

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型号：	PTH08T250WAS
厂家：	TEXAS INSTRUMENTS
描述：	50-A, 4.5-V to 14-V INPUT, NON-ISOLATED, WIDE-OUTPUT, ADJUSTABLE POWER MODULE WITH TurboTrans⑩ 50 -A ， 4.5 V至14 V输入，非隔离，宽输出，具有TurboTrans⑩调节电源模块电源电路输出元件输入元件
文件：	总38页 (文件大小：1384K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

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