PTH04T240F
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10-A, 2.2-V to 5.5-V INPUT, NON-ISOLATED
POWER MODULE FOR 3-GHz DSP SYSTEMS
FEATURES
1
•
•
•
•
•
•
2
•
•
•
•
•
•
•
•
Up to 10-A Output Current
2.2-V to 5.5-V Input Voltage
Wide-Output Voltage Adjust (0.69 V to 2.0 V)
±1.5% Total Output Voltage Variation
Efficiencies up to 94%
Output Overcurrent Protection
(Nonlatching, Auto-Reset)
Operating Temperature: –40°C to 85°C
Safety Agency Approvals:
– UL/IEC/CSA-C22.2 60950-1
Prebias Startup
On/Off Inhibit
Differential Output Voltage Remote Sense
Adjustable Undervoltage Lockout
Auto-Track™ Sequencing
SmartSync Technology
•
•
•
TurboTrans™ Technology
Designed to meet Ultra-Fast Transient
Requirements for 3-GHz DSP Systems
15 mV Output Voltage Deviation
(CO = 2000 µF, ΔI = 3 A)
APPLICATIONS
•
Wireless Infrastructure Base Stations
DESCRIPTION
The PTH04T240F is a high-performance 10-A rated, non-isolated power module designed to meet ultra-fast
transient requirements for 3-GHz DSP systems like Texas Instruments' TMS320TCI6488. This module is an
addition to the 2nd generation of the popular PTH series power modules which include a reduced footprint and
additional features.
Operating from an input voltage range of 2.2 V to 5.5 V, the PTH04T240F requires a single resistor to set the
output voltage to any value over the range, 0.69 V to 2.0 V. The output voltage range makes the PTH04T240F
particularly suitable for the 3-GHz DSP's core voltage requirements.
The module incorporates a comprehensive list of features. Output over-current 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.
The PTH04T240F 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. TurboTrans allows the PTH04T240F
to meet the tight transient voltage tolerances required by 3-GHz DSPs with minimal output capacitance.
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
2
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas
Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
Auto-Track, TurboTrans, 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.
Copyright © 2008–2009, Texas Instruments Incorporated
PTH04T240F
SLTS293A – DECEMBER 2008 – REVISED MARCH 2009 ............................................................................................................................................... www.ti.com
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.
PTH04T240F
SmartSync
Track
TurboTrans™
10
VI
Track
2
1
SYNC
TT
+Sense
VI
11 INH/UVLO
+
RUVLO
1%
0.05 W
(Optional)
CI
220 mF
(Required)
CI2
22 mF
(Optional)
6
+Sense
5
PTH04T240F
Inhibit
RTT
1%
0.05W
(Required)
9
VO
VO
-Sense
GND
GND
VOAdj
3
4
8
7
RSET[A]
1%
0.05 W
(Required)
L
O
A
D
+
CO
1000 mF
(Required)
GND
-Sense
GND
UDG-08158
A.
2
`RSET required to set the output voltage to a value higher than 0.69 V. See Electrical Characteristics table.
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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
PAGE NUMBER
ENVIRONMENTAL AND ABSOLUTE MAXIMUM RATINGS
3
ELECTRICAL CHARACTERISTICS TABLE (PTH04T240F)
4
TERMINAL FUNCTIONS
6
TYPICAL CHARACTERISTICS (VI = 5V)
7
TYPICAL CHARACTERISTICS (VI = 3.3V)
8
ADJUSTING THE OUTPUT VOLTAGE
9
INPUT & OUTPUT CAPACITOR RECOMMENDATIONS
11
TURBOTRANS™ INFORMATION
15
UNDERVOLTAGE LOCKOUT (UVLO)
19
SOFT-START POWER-UP
20
OUTPUT ON/OFF INHIBIT
21
SYCHRONIZATION (SMARTSYNC)
22
OVER-CURRENT PROTECTION
23
OVER-TEMPERATURE PROTECTION
23
REMOTE SENSE
23
AUTO-TRACK SEQUENCING
24
PREBIAS START-UP
27
TAPE & REEL DRAWING
28
SHIPPING TRAY DRAWING
29
ENVIRONMENTAL AND ABSOLUTE MAXIMUM RATINGS
(Voltages are with respect to GND)
UNIT
VTrack
Track pin voltage
–0.3 to VI + 0.3
TA
Operating temperature range Over VI range
Twave
Wave soldering temperature
Surface temperature of module body or
pins for 5 seconds maximum.
Treflow
Solder reflow temperature
Surface temperature of module body or
pins
Tstg
Storage temperature
(2)
suffix AS
suffix AZ
260
235
(1)
260
(1)
Mechanical shock
Per Mil-STD-883D, Method 2002.3 1 msec, 1/2 sine, mounted
500
Mechanical vibration
Mil-STD-883D, Method 2007.2 20-2000
Hz
suffix AD
20
suffix AS & AZ
15
Flammability
(1)
suffix AD
–55 to 125
Weight
V
–40 to 85
°C
(2)
3.8
G
grams
Meets UL94V-O
During reflow of surface mount package version do not elevate peak temperature of the module, pins or internal components above the
stated maximum.
The shipping tray or tape and reel cannot be used to bake parts at temperatures higher than 65°C.
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ELECTRICAL CHARACTERISTICS
PTH04T240F
TA = 25°C, VI = 5 V, VO = 1.0 V, CI = 220 µF, CO = 1000 µF, and IO = IO max (unless otherwise stated)
PARAMETER
TEST CONDITIONS
PTH04T240F
MIN
IO
Output current
Over VO range
VI
Input voltage range
Over IO range
VOADJ
Output voltage adjust range
Over IO range
25°C, natural convection
0.69 ≤ VO ≤ 1.7
1.7 < VO ≤ 2.0
η
0
10
5.5
VO+0.5 (1)
5.5
0.69
±0.3
%Vo
±3
mV
Load regulation
Over IO range
±2
Total output variation
Includes set-point, line, load, –40°C ≤ TA ≤ 85°C
IO = 10 A
RSET = 2.83 kΩ, VO = 2.0 V
91%
RSET = 4.78 kΩ, VO = 1.8 V
90%
RSET = 7.09 kΩ, VO = 1.5 V
88%
RSET = 12.1 kΩ, VO = 1.2 V
87%
RSET = 20.8 kΩ, VO = 1.0 V
85%
RSET = 689 kΩ, VO = 0.7 V
80%
20
Reset, followed by auto-recovery
20
A
200
µs
VO over/undershoot
28
mV
Recovery time
300
µs
VO over/undershoot
15
mV
2.5 A/µs load step
0.5 A to 3.5 A
VO = 0.9 V
dVtrack/dt
Track slew rate capability
CO ≤ CO (max)
Adjustable Under-voltage lockout
(pin 11)
CO = 1000 µF, TypeB
RTT = open
CO = 2000 µF, TypeB,
RTT = 23.7 kΩ
Recovery time
1
VI increasing, RUVLO = OPEN
1.95
VI decreasing, RUVLO = OPEN
1.5
Hysteresis, RUVLO = OPEN
0.5
Inhibit control (pin 11)
-0.2
Input low current (IIL), Pin 11 to GND
Input standby current
Inhibit (pin 11) to GND, Track (pin 10) open
fs
Switching frequency
Over VI and IO ranges, SmartSync (pin 1) to GND
fSYNC
Synchronization (SYNC)
frequency
VSYNCH
SYNC High-Level Input Voltage
VSYNCL
SYNC Low-Level Input Voltage
tSYNC
SYNC Minimum Pulse Width
CI
External input capacitance
4
0.8
V
µA
5
mA
300
kHz
240
400
kHz
2
5.5
V
200
Ceramic
V/ms
235
0.8
Nonceramic
µA
V
Open (4)
Input low voltage (VIL)
Iin
mVPP
–130 (3)
Input high voltage (VIH)
(5)
%Vo
Overcurrent threshold
Pin to GND
(4)
(2)
20-MHz bandwidth
Track input current (pin 10)
(3)
mV
±1.5
VO Ripple (peak-to-peak)
IIL
(1)
(2)
V
%Vo
Over VI range
ΔVtrTT
UVLOADJ
(2)
–40°C < TA < 85°C
Transient response
ttrTT
±1
V
Line regulaltion
ttr
ΔVtr
2.0
±0.5
A
Temperature variation
Efficiency
ILIM
UNIT
MAX
2.2
Set-point voltage tolerance
VO
TYP
220
V
ns
(5)
22
(5)
µF
The minimum input voltage is 2.2 V or (VO + 0.5) V, whichever is greater.
The set-point voltage tolerance is affected by the tolerance and stability of RSET. The stated limit is unconditionally met if RSET has a
tolerance of 1% with 100 ppm/C or better temperature stability.
A low-leakage ( 5000µF).
To ensure stability, the value of RTT must be calculated using the minimum required output capacitance
determined from the capacitor transient response charts above.
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TurboTrans
10
9
Auto Track
1
VI
TurboTrans
+Sense
Smart Sync
2
VI
PTH04T240F
11 Inhibit/
Prog UVLO
3
CI
220 mF
Required)
4
6
+Sense
5
VO
VO
-Sense
GND
+
RTT
18.7 kW
7
VOAdj
L
O
A
D
+
8
RSET
1%
0.05 W
CO
2200 mF
-Sense
GND
GND
UDG-08160
Figure 14. Typical TurboTrans™ Application
PTH04T240F
CO = 2200 mF
Without TurboTrans
(20 mV/div)
With TurboTrans
(20 mV/div)
2.5 A/ms
3 A Load Step
T - Time - 200 ms/div
Figure 15. Typical TurboTrans Waveforms
18
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UNDERVOLTAGE LOCKOUT (UVLO)
The PTH04T240F 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 input source during the power-up sequence.
The UVLO characteristic is defined by the ON threshold (VTHD) 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 PTH04T240F 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 16). When
pin 11 is left open circuit, the ON threshold voltage is internally set to the 1.95-V default value. The ON threshold
might need to be raised if the module is powered from a tightly regulated 5-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 RUVLO required to adjust VTHD to a new value. The default value is 1.95 V,
and it may be adjusted to a higher value only.
68.54 * V THD
R UVLO +
kW
V THD * 2.07
(4)
Table 6 lists the standard resistor values for RUVLO for different values of the on-threshold (VTHD) voltage.
Table 6. Standard RUVLO values for Various VTHD values
VTHD(V)
2.5
3.0
3.5
4.0
4.5
RUVLO (kΩ)
154
71.5
53.6
33.2
26.7
PTH04T240F
VI
2
VI
11
+
CI
GND
Inhibit/
UVLO Prog
GND
3
4
RUVLO
UDG-08161
Figure 16. Undervoltage Lockout Adjustment Resistor Placement
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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, VI (see Figure 17).
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
5 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 PTH04T240F operating from a 5-V input bus and configured for a 1.8-V output. The
waveforms were measured with a 10-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.
10
VI (2 V/div)
Track
PTH04T240F
VI
VO (500 mV/div)
2
VI
GND
+
CI
3
II (1 A/div)
4
GND
UDG-08162
T - Time - 4 ms/div
Figure 17. Defeating the Auto-Track Function
20
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Figure 18. Power-Up Waveform
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On/Off Inhibit
For applications requiring output voltage on/off control, the PTH04T240F 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 VI with 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 40
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, VINH. The waveforms were measured with a 10-A constant
current load.
VI
PTH04T240F
2
VI
VO (500 mV/div)
11
+
CI
1=Inhibit
Inhibit/
UVLO Prog
GND
3
II (1 A/div)
4
VI (2 V/div)
GND
UDG-08163
T - Time - 4 ms/div
Figure 19. On/Off Inhibit Control Circuit
Figure 20. Power-Up Response from Inhibit Control
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Smart Sync
Smart Sync is a feature that allows multiple power modules to be synchronized to a common frequency. 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 (see Electrical Specifications table for
synchronization limits). 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 < 10 kHz) allows the EMI filter to be designed to attenuate only the synchronization
frequency. Power modules can also be synchronized out of phase to minimize source current loading and
minimize input capacitance requirements. Figure 21 shows a standard circuit with two modules syncronized 180°
out of phase using a D flip-flop.
Track
0°
VI = 5 V
TT
SYNC
+Sense
VI
VO1
PTH08T220W
SN74LVC2G74
+
VCC
fCLK = 2 x fMODULE
CLR
PRE
CLK
Q
D
Q
GND
VO
Inhibit/
UVLO
-Sense
GND
CI1
330 mF
+
VOAdj
CO1
220 mF
RSET1
GND
180°
Track
Sync
TT
+Sense
VI
VO2
PTH04T240F
Inhibit/
UVLO
+
VO
-Sense
GND
VoAdj
CI2
220 mF
+
CO2
1000 mF
RSET2
GND
UDG-08164
Figure 21. Smart Sync Schematic
22
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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.
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 VO and 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. Connecting the +Sense (pin 6) to the positive load terminal improves the load
regulation at the connection point. For optimal behavior the –Sense (pin 7) must be connected to GND (pin 4)
close to the module (within 10 cm).
If the remote sense feature is not used at the load, connect the +Sense pin to VO (pin5) and connect the –Sense
pin to the module GND (pin 4).
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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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
Auto-Track works by forcing the module output voltage to follow a voltage presented at the Track control pin (1).
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 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 22.
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,
that includes a built-in time delay, is an ideal component for automatically controlling the Track inputs at power
up.
Figure 22 shows how a TPS3808 supply voltage supervisor IC (U3) can be used to coordinate the sequenced
power up of 5-V PTH modules. The output of the TPS3808 supervisor becomes active above an input voltage of
0.8 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 27ms after the
input voltage has risen above U3's voltage threshold, which is 4.65V. The 27-ms time period is controlled by the
capacitor C3. The value of 4700pF 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 23 shows the output voltage waveforms after input voltage is applied to the circuit. The waveforms, VO1
and VO2, represent the output voltages from the two power modules, U1 (3.3 V) and U2 (1.8 V), respectively.
VTRK, VO1, and VO2 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 24. 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.
24
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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 VI.
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 (VI). 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.
Auto Track
VI = 5 V
+Sense
VI
U1
PTH04T230W
C4
0.1 mF
VCC
MR
SENSE
-Sense
CT
RESET
VOAdj
GND
+
5
CO1
RSET1
1.21 kW
CI1
U3
TPS3808G50
4
VO1
3.3 V
VO
6
3
RTT
TurboTrans
1
GND
Auto Track
2
RTT
TurboTrans
+Sense
C3
4700 mF
VI
U2
PTH04T240F
VO2
1.8 V
Vo
-Sense
+
GND
VOAdj
RSET2
4.75 kW
CI2
CO2
UDG-08157
Figure 22. Sequenced Power Up and Power Down Using Auto-Track
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25
PTH04T240F
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VTRK (1 V/div)
VTRK (1 V/div)
VO1 (1 V/div)
VO1 (1 V/div)
VO2 (1 V/div)
VO2 (1 V/div)
T − Time − 200 µs/div
T − Time − 20 ms/div
Figure 23. Simultaneous Power Up
With Auto-Track Control
Figure 24. Simultaneous Power Down
With Auto-Track Control
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 25 shows an application demonstrating the prebias startup capability.
The startup waveforms are shown in Figure 26. Note that the output current (IO) is negligible until the output
voltage rises above the voltage backfed through the intrinsic diodes.
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 VI.
26
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Copyright © 2008–2009, Texas Instruments Incorporated
Product Folder Link(s): PTH04T240F
PTH04T240F
www.ti.com ............................................................................................................................................... SLTS293A – DECEMBER 2008 – REVISED MARCH 2009
3.3 V
Track
VI = 5 V
VI
+Sense
PTH04T240W
Inhibit GND
Vadj
VO
Vo = 2.5 V
Io
-Sense
VCCIO
VCORE
+
CI
330 mF
RSET
2.37 kW
CO
200 mF
ASIC
Figure 25. Application Circuit Demonstrating Prebias Startup
VIN (1 V/div)
VO (1 V/div)
IO (2 A/div)
t - Time = 4 ms/div
Figure 26. Prebias Startup Waveforms
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Copyright © 2008–2009, Texas Instruments Incorporated
Product Folder Link(s): PTH04T240F
27
PTH04T240F
SLTS293A – DECEMBER 2008 – REVISED MARCH 2009 ............................................................................................................................................... www.ti.com
TAPE AND REEL
28
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Copyright © 2008–2009, Texas Instruments Incorporated
Product Folder Link(s): PTH04T240F
PTH04T240F
www.ti.com ............................................................................................................................................... SLTS293A – DECEMBER 2008 – REVISED MARCH 2009
TRAY
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Copyright © 2008–2009, Texas Instruments Incorporated
Product Folder Link(s): PTH04T240F
29
PACKAGE OPTION ADDENDUM
www.ti.com
16-Jul-2020
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
(3)
Device Marking
(4/5)
(6)
PTH04T240FAD
ACTIVE
ThroughHole Module
EAY
11
49
RoHS Exempt
& Green
SN
N / A for Pkg Type
-40 to 85
PTH04T240FAS
ACTIVE
Surface
Mount Module
EAZ
11
49
Non-RoHS
& Green
SNPB
Level-1-235C-UNLIM/
Level-3-260C-168HRS
-40 to 85
PTH04T240FAZ
ACTIVE
Surface
Mount Module
BAZ
11
49
RoHS Exempt
& Green
SNAGCU
Level-3-260C-168 HR
-40 to 85
PTH04T240FAZT
ACTIVE
Surface
Mount Module
BAZ
11
250
RoHS Exempt
& Green
SNAGCU
Level-3-260C-168 HR
-40 to 85
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of
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