TI PT6728

PT6725 Series
14-A 12V-Input Adjustable
Integrated Switching Regulator
SLTS102A
(Revised 1/14/2002)
Features
•
•
•
•
•
•
•
•
•
Up to 14A Output Current
+12V Input
93% Efficiency (PT6724)
On/Off Standby Function
Differential Remote Sense
Adjustable Output Voltage
Short Circuit Protection
17-pin Space-Saving Package
Solderable Copper Case
Description
Ordering Information
The PT6725 series of power modules
are integrated switching regulators (ISRs),
housed in a 17-pin space saving solderable
copper package. These modules operate
off a 12V input power bus to provide up to
14A of low-voltage power for the industry’s latest high-speed, DSPs, µPs, and
bus drivers. The series includes the standard output bus voltage options, ranging
from 1.2V to 5.0V. The factory preset
voltage can also be adjusted over a limited range with a single external resistor.
Features include a Standby function,
output short circuit protection, and a
differential Remote Sense to compensate
for voltage drop between the ISR and
load. The modules are available in both
through-hole and surface mount configurations.
PT6724H
PT6725H
PT6726H
PT6727H
PT6728H
PT6729H
=
=
=
=
=
=
5.0
3.3
2.5
1.8
1.5
1.2
Pin-Out Information
Volts
Volts
Volts
Volts
Volts
Volts
Pin
PT Series Suffix (PT1234 x )
Case/Pin
Configuration
Order
Suffix
Package
Code *
N
A
C
Vertical
Horizontal
SMD
(EMD)
(EMA)
(EMC)
* Previously known as package styles 1340/50.
(Reference the applicable package code drawing
for the dimensions and PC board layout)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
Function
Vo Adjust
STBY*
Do Not Connect
Vin
Vin
Vin
Remote Sense Gnd
GND
GND
GND
GND
GND
Vout
Vout
Vout
Vout
Remote Sense Vout
* For further information, see
application notes.
Standard Application
STBY*
Vout Adjust
REMOTE SENSE (+)
2
VIN
L1
4-6
1µH
CIN
+
1
PT6725
8 - 12
17
VOUT
13 - 16
7
COUT
+
LOAD
REMOTE
SENSE (-)
GND
GND
Cin = Required 1000µF electrolytic
Cout= Required 330µF electrolytic
L1 = Optional 1µH input choke
For technical support and more information, see inside back cover or visit www.ti.com
PT6725 Series
14-A 12V-Input Adjustable
Integrated Switching Regulator
Specifications
(Unless otherwise stated, Ta =25°C, Vin =12V, C in =1,000µF, Cout =330µF, and I o =Iomax)
Characteristic
Symbol
Output Current
Io
Input Voltage Range
Set Point Voltage Tolerance
Temperature Variation
Line Regulation
Load Regulation
Total Output Voltage Variation
Vin
Vo tol
Regtemp
Regline
Regload
∆Votot
Efficiency
η
Vo Ripple (pk-pk)
Transient Response
Short Circuit Threshold
Switching Frequency
Remote On/Off (Pin 2)
Input High Voltage
Input Low Voltage
Input Low Current
Vr
ttr
∆Vtr
Isc threshold
ƒs
VIH
VIL
IIL
Standby Input Current
External Output Capacitance
External Input Capacitance
Operating Temperature Range
Storage Temperature
Reliability
Iin standby
Cout
Cin
Ta
Ts
MTBF
Mechanical Shock
—
Mechanical Vibration
—
Weight
Flammability
—
—
Conditions
Min
Ta =+60°C, 200LFM
Ta =+25°C, natural convection
Over Io Range
–40° ≤Ta ≤ +85°C, Io =Iomin
Over Vin range
Over Io range
Includes set-point, line, load,
–40° ≤Ta ≤ +85°C
Io =9.0A
20MHz bandwidth
5A/µs load step, 50% to 100% Iomax
Vo over/undershoot
Over Vin and Io range
Referenced to –Vin (pin 8)
pins 2 & 8 connected
See application schematic
See application schematic
Over Vin range
—
Per Bellcore TR-332
50% stress, Ta =40°C, ground benign
Per Mil-Std-883D, method 2002.3,
1ms, half-sine, mounted to a fixture
Mil-Std-883D, Method 2007.2,
20-2000Hz, soldered in PCB
Vo ≤2.5V
Vo >2.5V
Vo =5.0V
Vo =3.3V
Vo =2.5V
Vo =1.8V
Vo =1.5V
Vo =1.2V
PT6725 SERIES
Typ
Max
Units
0.1 (1)
0.1 (1)
10.8
—
—
—
—
—
—
—
±1
±0.5
±5
±5
14
13
13.2
±1.5 (2)
—
±10
±10
A
—
±2
±3
%Vo
—
—
—
—
—
—
—
—
—
—
300
93
90
87
84
81
78
35
70
±100
20
350
—
—
—
—
—
—
—
—
—
32
400
—
–0.1
—
—
330
1,000
-40 (4)
-40
—
—
–0.5
0.5
—
—
—
—
Open (3)
+0.4
–
1.0
15,000
—
+85 (5)
+125
mA
mA
µF
µF
°C
°C
7.8
—
—
106 Hrs
—
500
—
G’s
—
15 (6)
—
G’s
—
23
—
grams
VDC
%Vo
%Vo
mV
mV
%
mVpp
µs
mV
A
kHz
V
Materials meet UL 94V-0
Notes: (1) The ISR will operate at no load with reduced specifications.
(2) If the remote sense feature is not being used, connect the Remote Sense Gnd (pin 7) to GND (pin 8) for optimum output voltage accuracy.
(3) The STBY* control (pin 2) has an internal pull-up and if it is left open circuit the module will operate when input power is applied. The open-circuit
voltage is typically the input voltage, Vin. Refer to the application notes for other interface considerations.
(4) For operation below 0°C, Cin and Cout must have stable characteristics. Use either low ESR tantalum or Oscon® capacitors. See application notes.
(5) See Safe Operating Area curves or contact the factory for the appropriate derating.
(6) The case pins on through-hole package types (suffixes N & A) must be soldered. For more information see the applicable package outline drawing.
Input/Output Capacitors: For proper operation in all applications, the PT6725 series requires a 1,000µF input capacitor (Cin) with a minimum 1.6Arms ripple current
rating. And a 330µF output capacitor (Cout) with a maximum ESR of 50mΩ at 100kHz. For transient or dynamic load applications, additional output capacitance may be
necessary. The maximum allowable output capacitance is 15,000µF. For more information consult the related application note on capacitor recommendations.
Input Inductor: An input filter inductor is optioinal for most applications. The inductor must be sized to handle 6.5ADC with a typical value of 1µH.
For technical support and more information, see inside back cover or visit www.ti.com
Typical Characteristics
PT6725 Series
14-A 12V-Input Adjustable
Integrated Switching Regulator
Characteristic Data; Vin =12V
(See Note A)
Safe Operating Area; Vin =12V (See Note B)
Efficiency vs Output Current
PT6724, Vo =5.0V
100
90
Efficiency - %
VOUT
5.0V
3.3V
2.5V
1.8V
1.5V
1.2V
80
70
60
Ambient Temperature (°C)
80
90
Airflow
70
200LFM
120LFM
60LFM
Nat Conv
60
50
40
30
50
20
0
2
4
6
8
10
12
14
0
2
4
Iout (A)
8
10
12
14
Iout (A)
Output Ripple vs Output Current
PT6725, Vo =3.3V
60
90
VOUT
5.0V
3.3V
2.5V
1.8V
1.5V
1.2V
40
30
20
Ambient Temperature (°C)
80
50
Ripple - mV
6
10
70
Airflow
200LFM
120LFM
60LFM
Nat Conv
60
50
40
30
0
20
0
2
4
6
8
10
12
0
14
2
4
Iout (A)
6
8
10
12
14
Iout (A)
Power Dissipation vs Output Current
PT6726, Vo =2.5V
10
90
Pd - Watts
VOUT
5.0V
3.3V
2.5V
1.8V
1.5V
1.2V
6
4
2
Ambient Temperature (°C)
80
8
70
Airflow
200LFM
120LFM
60LFM
Nat Conv
60
50
40
30
0
20
0
2
4
6
8
10
12
14
0
2
4
Iout (A)
6
8
10
12
14
Iout (A)
PT6729, Vo =1.2V
90
Ambient Temperature (°C)
80
70
Airflow
200LFM
120LFM
60LFM
Nat Conv
60
50
40
30
20
0
2
4
6
8
10
12
Iout (A)
Note A: Characteristic data has been developed from actual products tested at 25°C. This data is considered typical data for the Converter.
Note B: SOA curves represent the conditions at which internal components are at or below the manufacturer’s maximum operating temperatures
For technical support and more information, see inside back cover or visit www.ti.com
14
Application Notes
PT6721/22 & PT6725 Series
Capacitor Recommendations for the 12V-Input
PT6721/22 and PT6725 Series of ISRs
Input Capacitors
The recommended input capacitor(s) is determined by
1.6Arms minimum ripple current rating and 1,000µF minimum capacitance. Ripple current and Equivalent Series
Resistance (ESR) values are the major considerations along
with temperature when selecting the proper capacitor.
The tantalum capacitors listed below cannot be used on
the input bus since they are not rated for 12V operation.
Output Capacitors
The minimum required output capacitance is 330µF with a
maximum ESR less than or equal to 50mΩ. Failure to
observe this requirement may lead to regulator instability
or oscillation. Electrolytic capacitors have poor ripple
performance at frequencies greater than 400kHz, but
excellent low frequency transient response. Above the
ripple frequency ceramic decoupling capacitors are necessary to improve the transient response and reduce any
microprocessor high frequency noise components apparent
during higher current excursions. Preferred low ESR type
capacitor part numbers are identified in the Table 1 below.
Tantalum Characteristics
Tantalum capacitors are recommended on the output bus
but only AVX TPS Series, Sprague 593D/594/595 Series,
or Kemet T495/T510 Series. These capacitors are recommended over other types due to their higher surge current,
excellent power dissipation and ripple current ratings. As a
caution, the TAJ Series by AVX is not recommended. This
series exhibits considerably higher ESR, reduced power
dissipation and lower ripple current capability. The TAJ
Series is also less reliable compared to the TPS series when
determining power dissipation capability.
Capacitor Table
Table 1 identifies the characteristics of capacitors from a
number of vendors with acceptable ESR and ripple current (rms) ratings. The suggested minimum quantities
per regulator for both the input and output buses are
identified.
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 (Equivalent Series Resistance at 100kHz) are the
critical parameters are necessary to insure both optimum
regulator performance and long capacitor life.
Table 1 Capacitors Characteristic Data
Capacitor Vendor/
Series
Capacitor Characteristics
Quantity
Working
Voltage
Value(µF)
(ESR) Equivalent
Series Resistance
105°C Maximum
Ripple
Current(Irms)
Physical
Size(mm)
Input
Bus
Output
Bus
Vendor Part Number
Panasonic
FC (Radial)
35V
25V
25V
680
1000
1000
0.043Ω
0.038Ω
0.038Ω
1655mA
1655mA
1690mA
12.5×20
12.5×20
16×15
2
1
1
1
2
1
EEUFC1V681
EEUFC1E102
EEUFC1E102S
FC/FK (Surface Mount)
50V
25V
35V
1000
1000
470
0073Ω
0.038Ω
0.043Ω
1610mA
2000mA
1690mA
16×16.5
18×16.5
16×16.5
1
1
2
1
1
1
EEVFK1H102M
EEVFC1E102N
EEVFC1V471N
United Chemi-con
LXV Series
35V
35V
16V
680
1000
470
0.034Ω
0.038Ω
0.084Ω÷2 =0.042Ω
1690mA
1630mA
825mA (×2)
12.5×25
16×20
10×16
2
1
2
1
1
1
LXV35VB680M12X25LL
LXV35VB102M16X20LL
LXV16VB471M10X16LL
Nichicon
PL Series
35V
25V
680
1200
0.036Ω
0.039Ω
1660mA
1600mA
12.5×25
18×15
2
1
1
1
UPL1V681MHH
UPL1E122MHH6
1
1
UPM1V102MHH6
1
1
10SS330M (Vo <5V)
10SV330 (Vo <5V)
PM Series
35V
1000
0.034Ω
1770mA
16×20
Os-con:
SS
SV (surface Mount)
10V
10V
330
330
0.025Ω
0.020Ω
3500mA
3800mA
10×10.5
10.3×10.3
AVX Tantalum
TPS (Surface Mount)
10V
10V
330
330
0.1Ω÷2 =0.05Ω
0.06Ω÷2 =0.03Ω
>2500mA
>3000mA
7.3L
×5.7W
×4.1H
N/R(1)
N/R(1)
2
2
TPSE337M010R0100
TPSV337M010R0060
Kemet Tantalum
T510/T495 Series
(Surface Mount)
10V
10V
330
220
0.033Ω
0.07Ω÷2 =0.035Ω
1400mA
>2000mA
4.3W
×7.3L
×4.0H
N/R(1)
N/R(1)
1
2
510X337M010AS
T495X227M0100AS
Sprague Tantalum
594D Series
(Surface Mount)
10V
330
0.045Ω
2360mA
7.2L
×6W
×4.1H
N/R(1)
1
594D337X0010R2T
Note: (N/R -Not recommended) The 10V-rated tantalum capacitors cannot be used on the input bus.
For technical support and more information, see inside back cover or visit www.ti.com
N/R(1)
N/R(1)
Application Notes
PT6725 Series
Using the Standby Function of the PT6725
Series of Integrated Switching Regulators
The PT6725 series of power modules are high efficiency
regulators that operate off a +12V input bus voltage.
These regulators incorporate an on/off ‘Standby’ function, which may be used to disable the regulator output.
Figure 1
The standby function is provided by the STBY* control,
pin 2. If pin 2 is left open-circuit the regulator operates
normally, and provides a regulated output when a valid
supply voltage is applied to Vin (pins 4–6) with respect to
GND (pins 8–12). If a low voltage 3 is then applied to
pin 2 the regulator output will be disabled and the input
current drawn by the ISR will be reduced to 0.5mA 1.
The standby control may also be used to hold-off the
regulator output during the period that input power is
applied.
+Vin
Pin 2 is ideally controlled with an open-collector (or
open-drain) discrete transistor (See Figure 1). The opencircuit voltage is typcially the input voltage Vin. Table 1
gives the circuit parameters for this control input.
Table 1 Standby Control Requirements (2, 3)
Parameter
Min
Typ
Input Low (V IL )
–0.1V
Max
+0.4V
Istby (pin 2 =ground)
—
–0.5mA
—
Vstby (open circuit)
—
Vin
—
Notes:
1. When the regulator output is disabled the current drawn
from the +Vin input source is typically reduced to 0.5mA.
2 The standby control input requires no external pull-up
resistor. The open-circuit voltage of the STBY* pin is
approximately th input voltage V in (+12V).
2
STBY*
4–6
PT6725
V IN
GND
8–12
Vo(adj)
1
V OUT
13–16
Vout
Sense(–)
7
+
+
CIN
C OUT
Q1
BSS138
STBY
GND
GND
Turn-On Time: In the circuit of Figure 1, turning Q1 on
applies a low voltage to the STBY control (pin 2) and
disables the regulator ouput. Correspondingly, turning
Q1 off removes the low-voltage signal and enables the
output. Once enabled, the output will typically experience
a 10–15ms delay followed by a predictable ramp-up of
voltage. The regulator should provide a fully regulated
output voltage within 30ms. Figure 2 shows the output
voltage response, Vo, of a PT6726 (2.5V) following the
turn-off of Q 1. The turn-off of Q1 corresponds to the
rise in V stby. The waveform was measured with a 12Vdc
input voltage, and 9.3ADC resistive load.
Figure 2
3. The standby control input is Not compatible with TTL
devices that incorporate a totem-pole output drive. Use
only a true open-collector device, preferably a discrete
bipolar transistor (or MOSFET). To ensure the regulator
output is disabled, the control pin must be pulled to less
than 0.4Vdc with a low-level 0.5mA sink to ground.
4. After Q1 in Figure 1 is turned off and before the output
begins to rise, the regulator output will assert a low
impedance to ground. If an external voltage is applied to
the output it will sink current and possibly over-stress the
part.
17
Sense(+)
Vo (1V/Div)
Vstby (10V/Div)
HORIZ SCALE: 5ms/Div
For technical support and more information, see inside back cover or visit www.ti.com
Application Notes
PT6725 Series
Adjusting the Output Voltage of the PT6725
Series of Integrated Switching Regulators
The PT6725 series of ISRs are non-programmable
versions of the PT6721/2 Excalibur™ regulators. The
regulators have a fixed output voltage, which may be
adjusted higher or lower than the factory pre-set voltage
using a single external resistor. Table 1 gives the adjustment range for each model in the series as Va (min) and
Va (max).
Figure 1
4,5,6
+5V
2
17
Stby*
Sns(+)
Vin
Vout
PT6725
GND
8–12
Vo(adj)
1
13–16
Vo
Sns(-)
7
(R1)
Adj Down
+
Adjust Down: Add a resistor (R1), between pin 1 (Vo Adjust)
and pin 17 (Remote Sense Vout).
+
Cin
Adjust Up: An increase in the output voltage is obtained by
adding a resistor R2, between pin 1 (Vo Adjust) and pin 7
(Remote Sense GND).
Cout
R2
Adjust Up
L
O
A
D
COM
COM
Refer to Figure 1 and Table 2 for both the placement and value
of the required resistor, either (R1) or R2 as appropriate.
The values of (R1) [adjust down], and R2 [adjust up], can
also be calculated using the following formulas.
(R1)
=
Ro ( Va –Vr )
Vo – Va
R2
=
Ro ·Vr
Va – V o
Where: Vo
Va
Vr
Ro
Rs
– Rs
– Rs
kΩ
kΩ
= Original output voltage
= Adjusted output voltage
= The reference voltage (Table 1)
= The multiplier resistance (Table 1)
= The internal series resistance (Table 1)
For technical support and more information, see inside back cover or visit www.ti.com
Notes:
1. Use only a single 1% resistor in either the (R1) or R2
location. Place the resistor as close to the regulator as
possible.
2. Never connect capacitors from Vo Adjust to either GND,
Vout, or the Remote Sense pins. Adding capacitance to the
Vo Adjust pin will affect the stability of the ISR.
3. If the Remote Sense feature is not being used, pin 7 must
be connected to pin 8 for optimum output voltage
accuracy. The resistors (R1) and R2 may then be connected
from ‘Vo Adjust’ to either Vout or GND respectively.
Application Notes continued
PT6705/PT6715 Series
Table 1
ADJUSTMENT AND FORMULA PARAMETERS
Series Pt #
Vo (nom)
Va (min)
Va (max)
Vr (V)
Ω)
Ro (kΩ
Ω)
Rs (kΩ
PT6729
PT6728
PT6727
PT6726
PT6725
PT6724
1.2
1.09
1.52
0.8
10.0
24.9
1.5
1.47
1.73
1.27
10.2
49.9
1.8
1.75
2.0
1.27
10.0
49.9
2.5
2.25
2.85
1.27
10.0
33.2
3.3
2.75
3.75
1.27
10.0
24.9
5.0
4.01
5.47
1.27
9.09
24.9
Table 2
ADJUSTMENT RESISTOR VALUES
Series Pt #
Vo (nom)
Va (req’d)
1.1
1.15
1.2
1.25
1.3
1.35
1.4
1.45
1.47
1.5
1.55
1.6
1.65
1.7
1.75
1.8
1.85
1.9
1.95
2.0
2.05
2.1
2.15
2.2
2.25
2.3
2.35
2.4
2.45
2.5
2.55
2.6
2.65
2.7
2.75
2.8
2.85
R1 = (Blue)
PT6729
1.2V
PT6728
1.5V
PT6727
1.8V
PT6726
2.5V
(5.1)kΩ
(45.1)kΩ
135.0kΩ
55.1kΩ
28.4kΩ
15.1kΩ
7.1kΩ
4.7kΩ
1.8kΩ
(18.1)kΩ
209.0kΩ
79.6kΩ
36.5kΩ
14.9kΩ
(46.1)kΩ
204.0kΩ
77.1kΩ
34.8kΩ
13.6kΩ
(6.0)kΩ
(18.3)kΩ
(38.8)kΩ
(79.8)kΩ
(203.0)kΩ
221.0kΩ
93.8kΩ
51.5kΩ
30.3kΩ
17.6kΩ
9.1kΩ
3.1k
Series Pt #
Vo (nom)
Va (req’d)
PT6725
3.3V
2.75
2.8
2.85
2.9
2.95
3.0
3.05
3.1
3.15
3.2
3.25
3.3
3.35
3.4
3.45
3.5
3.55
3.6
3.65
3.7
3.75
·
4.1
4.2
4.3
4.4
4.5
4.6
4.7
4.8
4.9
5.0
5.1
5.2
5.3
5.4
(2.0)kΩ
(5.7)kΩ
(10.2)kΩ
(15.9)kΩ
(23.1)kΩ
(32.8)kΩ
(46.3)kΩ
(66.6)kΩ
(100.0)kΩ
(168.0)kΩ
(371.0)kΩ
PT6724
5.0
229.0kΩ
102.0kΩ
59.8kΩ
38.6kΩ
25.9kΩ
17.4kΩ
11.4kΩ
6.9kΩ
3.3kΩ
(3.7)kΩ
(8.4)kΩ
(14.4)kΩ
(22.5)kΩ
(33.8)kΩ
(50.8)kΩ
(79.0)kΩ
(136.0)kΩ
(305.0)kΩ
90.5kΩ
32.8kΩ
13.6kΩ
4.0kΩ
R2 = Black
For technical support and more information, see inside back cover or visit www.ti.com
IMPORTANT NOTICE
Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications,
enhancements, improvements, and other changes to its products and services at any time and to discontinue
any product or service without notice. Customers should obtain the latest relevant information before placing
orders and should verify that such information is current and complete. All products are sold subject to TI’s terms
and conditions of sale supplied at the time of order acknowledgment.
TI warrants performance of its hardware products to the specifications applicable at the time of sale in
accordance with TI’s standard warranty. Testing and other quality control techniques are used to the extent TI
deems necessary to support this warranty. Except where mandated by government requirements, testing of all
parameters of each product is not necessarily performed.
TI assumes no liability for applications assistance or customer product design. Customers are responsible for
their products and applications using TI components. To minimize the risks associated with customer products
and applications, customers should provide adequate design and operating safeguards.
TI does not warrant or represent that any license, either express or implied, is granted under any TI patent right,
copyright, mask work right, or other TI intellectual property right relating to any combination, machine, or process
in which TI products or services are used. Information published by TI regarding third–party products or services
does not constitute a license from TI to use such products or services or a warranty or endorsement thereof.
Use of such information may require a license from a third party under the patents or other intellectual property
of the third party, or a license from TI under the patents or other intellectual property of TI.
Reproduction of information in TI data books or data sheets is permissible only if reproduction is without
alteration and is accompanied by all associated warranties, conditions, limitations, and notices. Reproduction
of this information with alteration is an unfair and deceptive business practice. TI is not responsible or liable for
such altered documentation.
Resale of TI products or services with statements different from or beyond the parameters stated by TI for that
product or service voids all express and any implied warranties for the associated TI product or service and
is an unfair and deceptive business practice. TI is not responsible or liable for any such statements.
Mailing Address:
Texas Instruments
Post Office Box 655303
Dallas, Texas 75265
Copyright  2001, Texas Instruments Incorporated