LINEAGEPOWER APTH012A0X3-SRZ

Data Sheet
May 20, 2009
Micro TLynxTM: Non-Isolated DC-DC Power Modules:
2.4Vdc –5.5Vdc input; 0.6Vdc to 3.63Vdc output; 12A Output Current
Features
EZ-SEQUENCETM
RoHS Compliant
Applications
ƒ
Compliant to RoHS EU Directive 2002/95/EC (Z
versions)
ƒ
Compatible in a Pb-free or SnPb reflow
environment (Z versions)
ƒ
Wide Input voltage range (2.4Vdc-5.5Vdc)
ƒ
Output voltage programmable from 0.6Vdc to 3.63
Vdc via external resistor
ƒ
Tunable Loop to optimize dynamic output
voltage response
ƒ
Flexible output voltage sequencing EZSEQUENCE – APTH versions
ƒ
Remote sense
ƒ
Fixed switching frequency
TM
ƒ
Distributed power architectures
ƒ
Output overcurrent protection (non-latching)
ƒ
Intermediate bus voltage applications
ƒ
Overtemperature protection
ƒ
Telecommunications equipment
ƒ
Remote On/Off
ƒ
Servers and storage applications
ƒ
Ability to sink and source current
ƒ
Networking equipment
ƒ
Cost efficient open frame design
ƒ
Industrial equipment
ƒ
Small size:
Vin+
VIN
Vout+
VOUT
SENSE
MODULE
RTUNE
SEQ
Cin
CTUNE
Q1
ON/OFF
GND
Co
TRIM
20.3 mm x 11.4 mm x 8.5 mm
(0.8 in x 0.45 in x 0.334 in)
ƒ
Wide operating temperature range (-40°C to 85°C)
ƒ
UL* 60950-1Recognized, CSA C22.2 No.
60950-1-03 Certified, and VDE‡ 0805:2001-12
(EN60950-1) Licensed
ƒ
ISO** 9001 and ISO 14001 certified manufacturing
facilities
†
RTrim
Description
TM
The Micro TLynx series of power modules are non-isolated dc-dc converters that can deliver up to 12A of output
current. These modules operate over a wide range of input voltage (VIN = 2.4Vdc-5.5Vdc) and provide a precisely
regulated output voltage from 0.6Vdc to 3.63Vdc, programmable via an external resistor. Features include remote
On/Off, adjustable output voltage, over current and overtemperature protection, and output voltage sequencing
(APTH versions). A new feature, the Tunable LoopTM, allows the user to optimize the dynamic response of the
converter to match the load with reduced amount of output capacitance leading to savings on cost and PWB area.
* UL is a registered trademark of Underwriters Laboratories, Inc.
†
CSA is a registered trademark of Canadian Standards Association.
VDE is a trademark of Verband Deutscher Elektrotechniker e.V.
** ISO is a registered trademark of the International Organization of Standards
‡
Document No: DS07-007 ver. 1.11
PDF name: APTH012A0X_ds.pdf
Preliminary Data Sheet
May 20, 2009
Austin MicroTLynx: Non-isolated DC-DC Power Modules:
2.4 – 5.5Vdc input; 0.6Vdc to 3.63Vdc output; 12A output current
Absolute Maximum Ratings
Stresses in excess of the absolute maximum ratings can cause permanent damage to the device. These are
absolute stress ratings only, functional operation of the device is not implied at these or any other conditions in
excess of those given in the operations sections of the data sheet. Exposure to absolute maximum ratings for
extended periods can adversely affect the device reliability.
Parameter
Device
Symbol
Min
Max
Unit
All
VIN
-0.3
6
Vdc
APTH
VSEQ
-0.3
ViN, Max
Vdc
All
TA
-40
85
°C
All
Tstg
-55
125
°C
Input Voltage
Continuous
Sequencing Voltage
Operating Ambient Temperature
(see Thermal Considerations section)
Storage Temperature
Electrical Specifications
Unless otherwise indicated, specifications apply over all operating input voltage, resistive load, and temperature
conditions.
Parameter
Device
Symbol
Min
Typ
2.4
⎯
Max
Unit
5.5
Vdc
11A
Adc
Operating Input Voltage
All
VIN
Maximum Input Current
All
IIN,max
VO,set = 0.6 Vdc
IIN,No load
36
mA
VO,set = 3.3Vdc
IIN,No load
81
mA
All
IIN,stand-by
3
mA
Inrush Transient
All
It
Input Reflected Ripple Current, peak-to-peak
(5Hz to 20MHz, 1μH source impedance; VIN =0 to
5.5V, IO= IOmax ; See Test Configurations)
All
49
mAp-p
Input Ripple Rejection (120Hz)
All
-30
dB
(VIN=2.4V to 5.5V, IO=IO, max )
Input No Load Current
(VIN = 5.0Vdc, IO = 0, module enabled)
Input Stand-by Current
(VIN = 5.0Vdc, module disabled)
LINEAGE POWER
2
1
2
As
2
Micro TLynxTM: Non-isolated DC-DC Power Modules:
2.4 – 5.5Vdc input; 0.6Vdc to 3.63Vdc output; 12A output current
Data Sheet
May 20, 2009
Electrical Specifications (continued)
Parameter
Device
Symbol
Min
Output Voltage Set-point
All
VO, set
-1.5
Output Voltage
All
VO, set
-3.0
All
VO
0.6
Typ
⎯
Max
Unit
+1.5
% VO, set
+3.0
% VO, set
3.63
Vdc
(Over all operating input voltage, resistive load,
and temperature conditions until end of life)
Adjustment Range
Selected by an external resistor
Output Regulation (for VO ≥ 2.5Vdc)
Line (VIN=VIN, min to VIN, max)
All
⎯
0.4
% VO, set
Load (IO=IO, min to IO, max)
All
⎯
10
mV
Line (VIN=VIN, min to VIN, max)
All
⎯
10
mV
Load (IO=IO, min to IO, max)
All
⎯
5
mV
Temperature (Tref=TA, min to TA, max)
All
⎯
0.4
% VO, set
0.5
V
Output Regulation (for VO < 2.5Vdc)
Remote Sense Range
All
Output Ripple and Noise on nominal output
(VIN=VIN, nom and IO=IO, min to IO, max Co = 0.1μF //
10 μF ceramic capacitors)
Peak-to-Peak (5Hz to 20MHz bandwidth)
All
⎯
25
35
mVpk-pk
RMS (5Hz to 20MHz bandwidth)
All
⎯
10
15
mVrms
External Capacitance
1
TM
Without the Tunable Loop
All
CO, max
0
⎯
200
μF
ESR ≥ 0.15 mΩ
All
CO, max
0
⎯
1000
μF
ESR ≥ 10 mΩ
All
CO, max
0
⎯
5000
μF
0
ESR ≥ 1 mΩ
With the Tunable Loop
TM
Output Current
All
Io
Output Current Limit Inception (Hiccup Mode )
All
IO, lim
12
Adc
200
% Io,max
Output Short-Circuit Current
All
IO, s/c
30
% Io,max
%
(VO≤250mV) ( Hiccup Mode )
Efficiency
VO,set = 0.6Vdc
η
75.0
VIN= 3.3Vdc, TA=25°C
VO, set = 1.2Vdc
η
85.5
%
IO=IO, max , VO= VO,set
VO,set = 1.8Vdc
η
89.9
%
VO,set = 2.5Vdc
η
92.7
%
VO,set = 3.3Vdc
η
94.6
All
fsw
Vin=5Vdc
Switching Frequency
1
⎯
600
%
⎯
kHz
TM
External capacitors may require using the new Tunable Loop feature to ensure that the module is stable as well as
TM
getting the best transient response. See the Tunable Loop section for details.
LINEAGE POWER
3
Micro TLynxTM: Non-isolated DC-DC Power Modules:
2.4 – 5.5Vdc input; 0.6Vdc to 3.63Vdc output; 12A output current
Data Sheet
May 20, 2009
General Specifications
Parameter
Min
Calculated MTBF (IO=IO, max, TA=25°C) Telecordia Issue 2, Method
1 Case 3
Max
Unit
28,160,677
⎯
Weight
Typ
Hours
⎯
3.59 (0.127)
g (oz.)
Feature Specifications
Unless otherwise indicated, specifications apply over all operating input voltage, resistive load, and temperature
conditions. See Feature Descriptions for additional information.
Devic
e
Parameter
On/Off Signal Interface
Symbol
Min
Typ
Max
Unit
(VIN=VIN, min to VIN, max ; open collector or equivalent,
Signal referenced to GND)
Device is with suffix “4” – Positive Logic (See Ordering
Information)
Logic High (Module ON)
Input High Current
Input High Voltage
All
IIH
⎯
⎯
10
µA
All
VIH
VIN – 1.6
⎯
VIN,max
V
All
All
IIL
VIL
⎯
-0.3
⎯
⎯
1
VIN – 0.8
mA
V
Logic Low (Module OFF)
Input Low Current
Input Low Voltage
Device Code with no suffix – Negative Logic (See Ordering
Information)
(On/OFF pin is open collector/drain logic input with
external pull-up resistor; signal referenced to GND)
Logic High (Module OFF)
Input High Current
All
IIH
―
―
1
mA
Input High Voltage
All
VIH
VIN – 1.6
―
VIN, max
Vdc
Input low Current
All
IIL
―
―
10
μA
Input Low Voltage
All
VIL
-0.2
―
VIN – 0.8
Vdc
All
Tdelay
―
2
―
msec
All
Tdelay
―
2
―
msec
All
Trise
―
5
―
msec
3.0
% VO,
Logic Low (Module ON)
Turn-On Delay and Rise Times
(VIN=VIN, nom, IO=IO, max , VO to within ±1% of steady state)
Case 1: On/Off input is enabled and then input power is
applied (delay from instant at which VIN = VIN, min until
Vo = 10% of Vo, set)
Case 2: Input power is applied for at least one second
and then the On/Off input is enabled (delay from instant
at which Von/Off is enabled until Vo = 10% of Vo, set)
Output voltage Rise time (time for Vo to rise from
10% of Vo, set to 90% of Vo, set)
o
Output voltage overshoot (TA = 25 C
VIN= VIN, min to VIN, max,IO = IO, min to IO, max)
With or without maximum external capacitance
Over Temperature Protection
All
Tref
130
°C
Sequencing Delay time
Delay from VIN, min to application of voltage on SEQ pin
APTH
TsEQ-delay
Tracking Accuracy
(Power-Up: 2V/ms)
APTHl
VSEQ –Vo
100
mV
(Power-Down: 2V/ms)
APTH
VSEQ –Vo
100
mV
(See Thermal Considerations section)
10
msec
(VIN, min to VIN, max; IO, min to IO, max VSEQ < Vo)
LINEAGE POWER
4
Data Sheet
May 20, 2009
Micro TLynxTM: Non-isolated DC-DC Power Modules:
2.4 – 5.5Vdc input; 0.6Vdc to 3.63Vdc output; 12A output current
Feature Specifications (continued)
Parameter
Device
Symbol
Min
Typ
Max
Units
Input Undervoltage Lockout
Turn-on Threshold
All
Turn-off Threshold
All
1.75
Hysteresis
All
0.08
LINEAGE POWER
2.2
Vdc
Vdc
0.2
Vdc
5
Micro TLynxTM: Non-isolated DC-DC Power Modules:
2.4 – 5.5Vdc input; 0.6Vdc to 3.63Vdc output; 12A output current
Data Sheet
May 20, 2009
Characteristic Curves
The following figures provide typical characteristics for the Micro TLynxTM at 0.6Vo and at 25oC.
13
OUTPUT CURRENT, Io (A)
90
EFFICIENCY, η (%)
85
80
Vin=2.4V
75
Vin=3.3V
Vin=5.5V
70
0
2
4
6
8
10
12
LINEAGE POWER
NC
8
35
45
55
65
75
85
VO (V) (200mV/div)
IO (A) (5Adiv)
OUTPUT CURRENT,
OUTPUT VOLTAGE
Figure 5. Typical Start-up Using On/Off Voltage (Io =
Io,max).
0.5m/s
(100LFM)
9
Figure 2. Derating Output Current versus Ambient
Temperature and Airflow.
TIME, t (20μs /div)
VO (V) (200mV/div)
Figure 4. Transient Response to Dynamic Load
Change from 0% to 50% to 0% with VIN=5V.
OUTPUT VOLTAGE
VO (V) (200mV/div)
VON/OFF (V) (2V/div)
TIME, t (1ms/div)
1m/s
(200LFM)
10
AMBIENT TEMPERATURE, TA C
VIN (V) (2V/div)
OUTPUT VOLTAGE
ON/OFF VOLTAGE
Figure 3. Typical output ripple and noise (VIN = 5V, Io =
Io,max).
2m/s
(400LFM)
O
INPUT VOLTAGE
VO (V) (10mV/div)
OUTPUT VOLTAGE
TIME, t (1μs/div)
11
25
OUTPUT CURRENT, IO (A)
Figure 1. Converter Efficiency versus Output Current.
12
TIME, t (1ms/div)
Figure 6. Typical Start-up Using Input Voltage (VIN =
5V, Io = Io,max).
6
Micro TLynxTM: Non-isolated DC-DC Power Modules:
2.4 – 5.5Vdc input; 0.6Vdc to 3.63Vdc output; 12A output current
Data Sheet
May 20, 2009
Characteristic Curves (continued)
95
13
90
12
OUTPUT CURRENT, Io (A)
EFFICIENCY, η (%)
The following figures provide typical characteristics for the Micro TLynx
85
Vin=2.4V
Vin=3.3V
Vin=5.5V
80
75
70
0
2
4
6
8
10
12
LINEAGE POWER
NC
8
35
45
55
65
75
85
VO (V) (200mV/div)
IO (A) (5Adiv)
OUTPUT CURRENT,
OUTPUT VOLTAGE
Figure 11. Typical Start-up Using On/Off Voltage (Io =
Io,max).
0.5m/s
(100LFM)
9
AMBIENT TEMPERATURE, TA C
TIME, t (20μs /div)
VO (V) (500mV/div)
Figure 10. Transient Response to Dynamic Load
Change from 0% to 50% to 0% with VIN=5V.
OUTPUT VOLTAGE
VO (V) (500mV/div)
VON/OFF (V) (2V/div)
TIME, t (1ms/div)
1m/s
(200LFM)
10
Figure 8. Derating Output Current versus Ambient
Temperature and Airflow.
VIN (V) (2V/div)
OUTPUT VOLTAGE
ON/OFF VOLTAGE
Figure 9. Typical output ripple and noise (VIN = 5V, Io =
Io,max).
2m/s
(400LFM)
O
INPUT VOLTAGE
VO (V) (10mV/div)
OUTPUT VOLTAGE
TIME, t (1μs/div)
o
at 1.2Vo and at 25 C.
11
25
OUTPUT CURRENT, IO (A)
Figure 7. Converter Efficiency versus Output Current.
TM
TIME, t (1ms/div)
Figure 12. Typical Start-up Using Input Voltage (VIN =
5V, Io = Io,max).
7
Micro TLynxTM: Non-isolated DC-DC Power Modules:
2.4 – 5.5Vdc input; 0.6Vdc to 3.63Vdc output; 12A output current
Data Sheet
May 20, 2009
Characteristic Curves (continued)
The following figures provide typical characteristics for the Micro TLynxTM at 1.8Vo and at 25oC.
13
100
OUTPUT CURRENT, Io (A)
EFFICIENCY, η (%)
95
90
85
Vin=2.4V
Vin=3.3V Vin=5.5V
80
75
70
0
2
4
6
8
10
12
LINEAGE POWER
NC
8
35
45
55
65
75
85
VO (V) (200mV/div)
IO (A) (2Adiv)
OUTPUT CURRENT,
OUTPUT VOLTAGE
Figure 17. Typical Start-up Using On/Off Voltage (Io =
Io,max).
0.5m/s
(100LFM)
9
Figure 14. Derating Output Current versus Ambient
Temperature and Airflow.
TIME, t (20μs /div)
VO (V) (1V/div)
Figure 16. Transient Response to Dynamic Load
Change from 0% to 50% to 0% with VIN=5V.
OUTPUT VOLTAGE
VO (V) (500mV/div)
VON/OFF (V) (2V/div)
TIME, t (1ms/div)
1m/s
(200LFM)
10
AMBIENT TEMPERATURE, TA C
VIN (V) (2V/div)
OUTPUT VOLTAGE
ON/OFF VOLTAGE
Figure 15. Typical output ripple and noise (VIN = 5V, Io =
Io,max).
2m/s
(400LFM)
O
INPUT VOLTAGE
VO (V) (10mV/div)
OUTPUT VOLTAGE
TIME, t (1μs/div)
11
25
OUTPUT CURRENT, IO (A)
Figure 13. Converter Efficiency versus Output Current.
12
TIME, t (1ms/div)
Figure 18. Typical Start-up Using Input Voltage (VIN =
5V, Io = Io,max).
8
Micro TLynxTM: Non-isolated DC-DC Power Modules:
2.4 – 5.5Vdc input; 0.6Vdc to 3.63Vdc output; 12A output current
Data Sheet
May 20, 2009
Characteristic Curves (continued)
The following figures provide typical characteristics for the Micro TLynx
OUTPUT CURRENT, Io (A)
EFFICIENCY, η (%)
95
90
Vin=5.5V
Vin=3V
Vin=3.3V
85
80
0
2
4
6
8
10
12
LINEAGE POWER
1m/s
(200LFM)
0.5m/s
(100LFM)
9
NC
8
35
45
55
65
75
85
OUTPUT VOLTAGE
VO (V) (200mV/div)
IO (A) (5Adiv)
OUTPUT CURRENT,
TIME, t (20μs /div)
Figure 22. Transient Response to Dynamic Load
Change from 0% to 50% to 0% with VIN=5V.
VO (V) (1V/div)
VO (V) (1V/div)
Figure 23. Typical Start-up Using On/Off Voltage (Io =
Io,max).
10
AMBIENT TEMPERATURE, TA C
OUTPUT VOLTAGE
OUTPUT VOLTAGE
TIME, t (1ms/div)
2m/s
(400LFM)
Figure 20. Derating Output Current versus Ambient
Temperature and Airflow.
VIN (V) (2V/div)
TIME, t (1μs/div)
Figure 21. Typical output ripple and noise (VIN = 5V, Io =
Io,max).
11
O
INPUT VOLTAGE
VO (V) (0mV/div)
OUTPUT VOLTAGE
Figure 19. Converter Efficiency versus Output Current.
12
25
OUTPUT CURRENT, IO (A)
VON/OFF (V) (5V/div)
o
at 2.5Vo and at 25 C.
13
100
ON/OFF VOLTAGE
TM
TIME, t (1ms/div)
Figure 24. Typical Start-up Using Input Voltage (VIN =
5V, Io = Io,max).
9
Micro TLynxTM: Non-isolated DC-DC Power Modules:
2.4 – 5.5Vdc input; 0.6Vdc to 3.63Vdc output; 12A output current
Data Sheet
May 20, 2009
Characteristic Curves (continued)
The following figures provide typical characteristics for the Micro TLynxTM at 3.3Vo and at 25oC.
13
OUTPUT CURRENT, Io (A)
100
EFFICIENCY, η (%)
95
Vin=5V
Vin=5.5V
Vin=4.5V
90
85
80
0
2
4
6
8
10
12
LINEAGE POWER
0.5m/s
(100LFM)
NC
9
8
35
45
55
65
75
85
VO (V) (200mV/div)
IO (A) (5Adiv)
OUTPUT CURRENT,
OUTPUT VOLTAGE
Figure 29. Typical Start-up Using On/Off Voltage (Io =
Io,max).
1m/s
(200LFM)
Figure 26. Derating Output Current versus Ambient
Temperature and Airflow.
TIME, t (20μs /div)
VO (V) (1V/div)
Figure 28. Transient Response to Dynamic Load
Change from 0% 50% to 0% with VIN=5V.
OUTPUT VOLTAGE
VO (V) (1V/div)
VON/OFF (V) (2V/div)
TIME, t (1ms/div)
10
AMBIENT TEMPERATURE, TA C
VIN (V) (2V/div)
OUTPUT VOLTAGE
ON/OFF VOLTAGE
Figure 27. Typical output ripple and noise (VIN = 5V, Io =
Io,max).
2m/s
(400LFM)
O
INPUT VOLTAGE
VO (V) (10mV/div)
OUTPUT VOLTAGE
TIME, t (1μs/div)
11
25
OUTPUT CURRENT, IO (A)
Figure 25. Converter Efficiency versus Output Current.
12
TIME, t (1ms/div)
Figure 30. Typical Start-up Using Input Voltage (VIN =
5V, Io = Io,max).
10
Micro TLynxTM: Non-isolated DC-DC Power Modules:
2.4 – 5.5Vdc input; 0.6Vdc to 3.63Vdc output; 12A output current
Data Sheet
May 20, 2009
Test Configurations
Design Considerations
CURRENT PROBE
TO OSCILLOSCOPE
LTEST
VIN(+)
BATTERY
1μH
CIN
CS 1000μF
Electrolytic
2x100μF
Tantalum
E.S.R.<0.1Ω
@ 20°C 100kHz
COM
NOTE: Measure input reflected ripple current with a simulated
source inductance (LTEST) of 1μH. Capacitor CS offsets
possible battery impedance. Measure current as shown
above.
Figure 31. Input Reflected Ripple Current Test
Setup.
Input Filtering
TM
The Micro TLynx module should be connected to a
low ac-impedance source. A highly inductive source
can affect the stability of the module. An input
capacitance must be placed directly adjacent to the
input pin of the module, to minimize input ripple
voltage and ensure module stability.
To minimize input voltage ripple, low-ESR ceramic
capacitors are recommended at the input of the module.
Figure 34 shows the input ripple voltage for various
output voltages at 3A of load current with 1x47 µF or
2x47 µF ceramic capacitors and an input of 5V. Figure
35 shows data for the 3.3Vin case, with 1x47µF or
2x37µF of ceramic capacitors at the input.
140
120
100
COPPER STRIP
80
RESISTIVE
LOAD
Vo+
10uF
0.1uF
60
40
1x47uF
20
COM
SCOPE USING
BNC SOCKET
GROUND PLANE
2x47uF
0
0.5
NOTE: All voltage measurements to be taken at the module
terminals, as shown above. If sockets are used then
Kelvin connections are required at the module terminals
to avoid measurement errors due to socket contact
resistance.
Figure 32. Output Ripple and Noise Test Setup.
1
1.5
2
2.5
3
3.5
Figure 34. Input ripple voltage for various output
voltages with 1x47 µF or 2x47 µF ceramic
capacitors at the input (12A load). Input voltage is
5V.
120
Rdistribution
Rcontact
Rcontact
VIN(+)
Rdistribution
VO
100
80
VO
VIN
Rdistribution
RLOAD
Rcontact
Rcontact
COM
Rdistribution
60
40
1x47uF
COM
20
NOTE: All voltage measurements to be taken at the module
terminals, as shown above. If sockets are used then
Kelvin connections are required at the module terminals
to avoid measurement errors due to socket contact
resistance.
Figure 33. Output Voltage and Efficiency Test Setup.
VO. IO
Efficiency
η =
LINEAGE POWER
VIN. IIN
x
2x47uF
0
0.5
1
1.5
2
2.5
3
Figure 35. Input ripple voltage in mV, p-p for
various output voltages with 1x47 µF or 2x47 µF
ceramic capacitors at the input (12A load). Input
voltage is 3.3V.
100 %
11
Micro TLynxTM: Non-isolated DC-DC Power Modules:
2.4 – 5.5Vdc input; 0.6Vdc to 3.63Vdc output; 12A output current
Data Sheet
May 20, 2009
Output Filtering
To reduce the output ripple and improve the dynamic
response to a step load change, additional capacitance
at the output can be used. Low ESR ceramic and
polymer capacitors are recommended to improve the
dynamic response of the module. Figure 36 provides
output ripple information for different external
capacitance values at various Vo and for load currents
of 12A while maintaining an input voltage of 5V. Fig 37
shows the performance with a 3.3V input. For stable
operation of the module, limit the capacitance to less
than the maximum output capacitance as specified in
the electrical specification table. Optimal performance
of the module can be achieved by using the Tunable
TM
Loop feature described later in this data sheet.
Ripple(mVp-p)
15
1x10uF External Cap
1x47uF External Cap
2x47uF External Cap
4x47uF External Cap
10
5
Ripple(mVp-p)
15
The Micro TLynxTM modules are designed for low output
ripple voltage and will meet the maximum output ripple
specification with 0.1 µF ceramic and 10 µF ceramic
capacitors at the output of the module. However,
additional output filtering may be required by the system
designer for a number of reasons. First, there may be a
need to further reduce the output ripple and noise of the
module. Second, the dynamic response characteristics
may need to be customized to a particular load step
change.
1x10uF External Cap
1x47uF External Cap
2x47uF External Cap
4x47uF External Cap
10
5
0
0.5
1
1.5
2
Output Voltage(Volts)
2.5
3
Figure 37. Output ripple voltage for various output
voltages with external 1x10 µF, 1x47 µF, 2x47 µF or
4x47 µF ceramic capacitors at the output (12A load).
Input voltage is 3.3V.
Safety Considerations
For safety agency approval the power module must be
installed in compliance with the spacing and separation
requirements of the end-use safety agency standards,
i.e., UL 60950-1, CSA C22.2 No. 60950-1-03, and VDE
0850:2001-12 (EN60950-1) Licensed.
For the converter output to be considered meeting the
requirements of safety extra-low voltage (SELV), the
input must meet SELV requirements. The power
module has extra-low voltage (ELV) outputs when all
inputs are ELV.
Feature Descriptions
Remote On/Off
TM
0
0.5
1
1.5
2
2.5
3
3.5
Output Voltage(Volts)
Figure 36. Output ripple voltage for various output
voltages with external 1x10 µF, 1x47 µF, 2x47 µF or
4x47 µF ceramic capacitors at the output (12A load).
Input voltage is 5V.
LINEAGE POWER
The Micro TLynx modules feature an On/Off pin for
remote On/Off operation. Two On/Off logic options are
available. In the Positive Logic On/Off option, (device
code suffix “4” – see Ordering Information), the module
turns ON during a logic High on the On/Off pin and turns
OFF during a logic Low. With the Negative Logic
On/Off option, (no device code suffix, see Ordering
Information), the module turns OFF during logic High
and ON during logic Low. The On/Off signal is always
referenced to ground. For either On/Off logic option,
leaving the On/Off pin disconnected will turn the module
ON when input voltage is present.
For positive logic modules, the circuit configuration for
using the On/Off pin is shown in Figure 38. For positive
logic modules, the circuit configuration for using the
On/Off pin is shown in Figure 38. When the external
transistor Q1 is in the OFF state, Q2 is ON, the internal
PWM Enable signal is pulled low and the module is ON.
When transistor Q1 is turned ON, the On/Off pin is
12
Micro TLynxTM: Non-isolated DC-DC Power Modules:
2.4 – 5.5Vdc input; 0.6Vdc to 3.63Vdc output; 12A output current
Data Sheet
May 20, 2009
pulled low, Q2 is turned off and the internal PWM
Enable signal is pulled high through the 23.7K pull-up
resistor and the module is OFF.
VIN+
Overtemperature Protection
MODULE
23.7K
20K
470
I ON/OFF
ON/OFF
Q1
PWM Enable
Q2
+
VON/OFF
unit enters hiccup mode. The unit operates normally
once the output current is brought back into its specified
range.
To provide protection in a fault condition, the unit is
equipped with a thermal shutdown circuit. The unit will
shutdown if the overtemperature threshold of 130oC is
exceeded at the thermal reference point Tref . The
thermal shutdown is not intended as a guarantee that
the unit will survive temperatures beyond its rating.
Once the unit goes into thermal shutdown it will then
wait to cool before attempting to restart.
Input Undervoltage Lockout
20K
At input voltages below the input undervoltage lockout
limit, the module operation is disabled. The module will
begin to operate at an input voltage above the
undervoltage lockout turn-on threshold.
_
GND
Figure 38. Circuit configuration for using positive
On/Off logic.
Output Voltage Programming
For negative logic On/Off modules, the circuit
configuration is shown in Fig. 39. The On/Off pin should
be pulled high with an external pull-up resistor
(suggested value for the 2.4V to 5.5Vin range is
3Kohms). When transistor Q1 is in the OFF state, the
On/Off pin is pulled high and the module is OFF. The
On/Off threshold for logic High on the On/Off pin
depends on the input voltage and its minimum value is
VIN – 1.6V. To turn the module ON, Q1 is turned ON
pulling the On/Off pin low.
The output voltage of the Micro TLynx module can be
programmed to any voltage from 0.6dc to 3.63Vdc by
connecting a resistor between the Trim+ and GND pins
of the module. Certain restrictions apply on the output
voltage set point depending on the input voltage. These
are shown in the Output Voltage vs. Input Voltage Set
Point Area plot in Fig. 40. The Upper Limit curve shows
that the entire output voltage range is available with the
maximum input voltage of 5.5V. The Lower Limit curve
shows that for output voltages of 1.8V and higher, the
input voltage needs to be larger than the minimum of
2.4V.
VIN+
TM
6
MODULE
60.4K
I ON/OFF
ON/OFF
+
R2
VON/OFF
Q1
PWM Enable
Input Voltage (v)
5
Rpullup
Upper Limit
4
3
Lower Limit
2
1
20K
0
0.5
GND
_
Figure 39. Circuit configuration for using negative
On/Off logic.
Overcurrent Protection
To provide protection in a fault (output overload)
condition, the unit is equipped with internal
current-limiting circuitry and can endure current limiting
continuously. At the point of current-limit inception, the
LINEAGE POWER
1
1.5
2
2.5
3
3.5
4
Output Voltage (V)
Figure 40. Output Voltage vs. Input Voltage Set
Point Area plot showing limits where the output
voltage can be set for different input voltages.
Without an external resistor between Trim+ and GND
pins, the output of the module will be 0.6Vdc. To
calculate the value of the trim resistor, Rtrim for a
desired output voltage, use the following equation:
13
Micro TLynxTM: Non-isolated DC-DC Power Modules:
2.4 – 5.5Vdc input; 0.6Vdc to 3.63Vdc output; 12A output current
Data Sheet
May 20, 2009
Voltage Margining
⎡ 1.2 ⎤
Rtrim = ⎢
⎥ kΩ
⎣ (Vo − 0.6 )⎦
Rtrim is the external resistor in kΩ, and Vo is the desired
output voltage.
Table 1 provides Rtrim values required for some
common output voltages.
Table 1
VO, set (V)
Rtrim (KΩ)
0.6
1.0
1.2
1.5
1.8
2.5
3.3
Open
3.0
2.0
1.333
1.0
0.632
0.444
Output voltage margining can be implemented in the
Micro TLynxTM modules by connecting a resistor, Rmarginup, from the Trim pin to the ground pin for margining-up
the output voltage and by connecting a resistor, Rmargindown, from the Trim pin to output pin for margining-down.
Figure 42 shows the circuit configuration for output
voltage margining. The POL Programming Tool,
available at www.lineagepower.com under the Design
Tools section, also calculates the values of Rmargin-up and
Rmargin-down for a specific output voltage and % margin
Please consult your local Lineage Power technical
representative for additional details.
Vo
Rmargin-down
MODULE
Q2
By using a ±0.5% tolerance trim resistor with a TC of
±25ppm, a set point tolerance of ±1.5% can be achieved
as specified in the electrical specification. The POL
Programming Tool available at www.lineagepower.com
under the Design Tools section, helps determine the
required trim resistor needed for a specific output
voltage.
Trim
Rmargin-up
Rtrim
Q1
GND
VI N+
VO +
Figure 42. Circuit Configuration for margining
Output voltage
SENSE
ON/OFF
TRIM
LOAD
Rtrim
GND
Monotonic Start-up and Shutdown
TM
The Micro TLynx modules have monotonic start-up
and shutdown behavior for any combination of rated
input voltage, output current and operating temperature
range.
Startup into Pre-biased Output
TM
Figure 41. Circuit configuration for programming
output voltage using an external resistor.
Remote Sense
TM
The Micro TLynx modules have a Remote Sense
feature to minimize the effects of distribution losses by
regulating the voltage at the SENSE pin. The voltage
between the SENSE pin and VOUT pin must not
exceed 0.5V. Note that the output voltage of the module
cannot exceed the specified maximum value. This
includes the voltage drop between the SENSE and Vout
pins. When the Remote Sense feature is not being
used, connect the SENSE pin to the VOUT pin.
LINEAGE POWER
The 5.5V Pico TLynx 12A modules can start into a
prebiased output as long as the prebias voltage is 0.5V
less than the set output voltage. Note that prebias
operation is not supported when output voltage
sequencing is used.
Output Voltage Sequencing
The APTH012A0X modules include a sequencing
feature, EZ-SEQUENCE that enables users to
implement various types of output voltage sequencing in
their applications. This is accomplished via an
additional sequencing pin. When not using the
sequencing feature, either tie the SEQ pin to VIN or
leave it unconnected.
14
Micro TLynxTM: Non-isolated DC-DC Power Modules:
2.4 – 5.5Vdc input; 0.6Vdc to 3.63Vdc output; 12A output current
Data Sheet
May 20, 2009
When an analog voltage is applied to the SEQ pin, the
output voltage tracks this voltage until the output
reaches the set-point voltage. The final value of the
SEQ voltage must be set higher than the set-point
voltage of the module. The output voltage follows the
voltage on the SEQ pin on a one-to-one volt basis. By
connecting multiple modules together, multiple modules
can track their output voltages to the voltage applied on
the SEQ pin.
For proper voltage sequencing, first, input voltage is
applied to the module. The On/Off pin of the module is
left unconnected (or tied to GND for negative logic
modules or tied to VIN for positive logic modules) so that
the module is ON by default. After applying input
voltage to the module, a minimum 10msec delay is
required before applying voltage on the SEQ pin. This
delay gives the module enough time to complete its
internal power-up soft-start cycle. During the delay time,
the SEQ pin should be held close to ground (nominally
50mV ± 20 mV). This is required to keep the internal opamp out of saturation thus preventing output overshoot
during the start of the sequencing ramp. By selecting
resistor R1 (see fig. 43) according to the following
equation
R1 =
voltage must be maintained until the tracking and output
voltages reach ground potential.
TM
When using the EZ-SEQUENCE feature to control
start-up of the module, pre-bias immunity during start-up
is disabled. The pre-bias immunity feature of the
module relies on the module being in the diode-mode
TM
during start-up. When using the EZ-SEQUENCE
feature, modules goes through an internal set-up time of
10msec, and will be in synchronous rectification mode
when the voltage at the SEQ pin is applied. This will
result in the module sinking current if a pre-bias voltage
is present at the output of the module. When pre-bias
immunity during start-up is required, the EZTM
SEQUENCE feature must be disabled. For
additional guidelines on using the EZ-SEQUENCETM
feature please refer to Application Note AN04-008
“Application Guidelines for Non-Isolated Converters:
Guidelines for Sequencing of Multiple Modules”, or
contact the Lineage Power technical representative for
additional information.
24950
ohms,
V IN − 0.05
the voltage at the sequencing pin will be 50mV when
the sequencing signal is at zero.
MODULE
VIN+
499K
+
OUT
R1
SEQ
10K
-
GND
Figure 43. Circuit showing connection of the
sequencing signal to the SEQ pin.
After the 10msec delay, an analog voltage is applied to
the SEQ pin and the output voltage of the module will
track this voltage on a one-to-one volt bases until the
output reaches the set-point voltage. To initiate
simultaneous shutdown of the modules, the SEQ pin
voltage is lowered in a controlled manner. The output
voltage of the modules tracks the voltages below their
set-point voltages on a one-to-one basis. A valid input
LINEAGE POWER
15
Micro TLynxTM: Non-isolated DC-DC Power Modules:
2.4 – 5.5Vdc input; 0.6Vdc to 3.63Vdc output; 12A output current
Data Sheet
May 20, 2009
Tunable LoopTM
TM
The 5V Pico TLynx 12A modules have a new feature
that optimizes transient response of the module called
TM
Tunable Loop .
External capacitors are usually added to the output of
the module for two reasons: to reduce output ripple and
noise (see Figures 36 and 37) and to reduce output
voltage deviations from the steady-state value in the
presence of dynamic load current changes. Adding
external capacitance however affects the voltage control
loop of the module, typically causing the loop to slow
down with sluggish response. Larger values of external
capacitance could also cause the module to become
unstable.
TM
The Tunable Loop allows the user to externally adjust
the voltage control loop to match the filter network
connected to the output of the module. The Tunable
TM
Loop is implemented by connecting a series R-C
between the SENSE and TRIM pins of the module, as
shown in Fig. 44. This R-C allows the user to externally
adjust the voltage loop feedback compensation of the
module.
RTUNE
MODULE
CO
CTUNE
TRIM
RTrim
Figure. 44. Circuit diagram showing connection of
RTUME and CTUNE to tune the control loop of the
module.
Recommended values of RTUNE and CTUNE for different
output capacitor combinations are given in Tables 2, 3,
4 and 5. Tables 2 and 4 show the recommended values
of RTUNE and CTUNE for different values of ceramic output
capacitors up to 940μF that might be needed for an
application to meet output ripple and noise requirements
for 5Vin and 3.3Vin respectively. Selecting RTUNE and
CTUNE according to Table 2 will ensure stable operation
of the module.
In applications with tight output voltage limits in the
presence of dynamic current loading, additional output
capacitance will be required. Tables 3 and 5 list
recommended values of RTUNE and CTUNE in order to
meet 2% output voltage deviation limits for some
common output voltages in the presence of a 1.5A to 3A
LINEAGE POWER
Please contact your Lineage Power technical
representative to obtain more details of this feature as
well as for guidelines on how to select the right value of
external R-C to tune the module for best transient
performance and stable operation for other output
capacitance values or input voltages other than 5 or
3.3V.
Table 2. General recommended values of of RTUNE
and CTUNE for Vin=5V and various external ceramic
capacitor combinations.
Cext
1x47μF
2x47μF
4x47μF
10x47μF
20x47μF
RTUNE
47
47
47
33
22
CTUNE
1500pF
3900pF
10nF
33nF
56nF
Table 3. Recommended values of RTUNE and CTUNE to
obtain transient deviation of 2% of Vout for a 6A
step load with Vin=5V.
Vout
3.3V
2.5V
1.8V
1.2V
1x47μF 4x47μF
4x47μF
330μF
+
330μF
+
330μF
+
2x330μF
Cext Polymer
Polymer Polymer
Polymer
Cap
Cap
Cap
Cap
VOUT
SENSE
GND
step change (50% of full load), with an input voltage of
5Vin and 3.3Vin respectively
0.6V
6x330μF
Polymer
Cap
RTUNE
56
33
33
33
33
CTUNE
15nF
18nF
27nF
47nF
220nF
ΔV
66mV
49mV
35mV
24mV
12mV
Table 4. General recommended values of of RTUNE
and CTUNE for Vin=3.3V and various external ceramic
capacitor combinations.
Cext
1x47μF
2x47μF
4x47μF
10x47μF
20x47μF
RTUNE
47
47
33
33
22
CTUNE
3300pF
6800pF
15nF
47nF
68nF
Table 5. Recommended values of RTUNE and CTUNE to
obtain transient deviation of 2% of Vout for a 6A
step load with Vin=3.3V.
Vout
2.5V
1.8V
1.2V
0.6V
Cext
2 x 330μF
Polymer
Cap
2 x 330μF
Polymer
Cap
3 x 330μF
Polymer
Cap
7 x 330μF
Polymer
Cap
RTUNE
33
33
33
33
CTUNE
82nF
100nF
180nF
390nF
ΔV
45mV
32mV
24mV
12mV
16
Micro TLynxTM: Non-isolated DC-DC Power Modules:
2.4 – 5.5Vdc input; 0.6Vdc to 3.63Vdc output; 12A output current
Data Sheet
May 20, 2009
Thermal Considerations
Power modules operate in a variety of thermal
environments; however, sufficient cooling should always
be provided to help ensure reliable operation.
Considerations include ambient temperature, airflow,
module power dissipation, and the need for increased
reliability. A reduction in the operating temperature of
the module will result in an increase in reliability. The
thermal data presented here is based on physical
measurements taken in a wind tunnel. The test set-up
is shown in Figure 45. The preferred airflow direction
for the module is shown in Figure 46.
Figure 46. Preferred airflow direction and location of
hot-spot of the module (Tref).
25.4_
(1.0)
Wind Tunnel
PWBs
Power Module
76.2_
(3.0)
x
12.7_
(0.50)
Probe Location
for measuring
airflow and
ambient
temperature
Air
flow
Figure 45. Thermal Test Setup.
The thermal reference points, Tref used in the
specifications are shown in Figure 46. For reliable
operation the temperatures at these points should not
o
exceed 125 C. The output power of the module should
not exceed the rated power of the module (Vo,set x
Io,max).
Please refer to the Application Note “Thermal
Characterization Process For Open-Frame BoardMounted Power Modules” for a detailed discussion of
thermal aspects including maximum device
temperatures.
LINEAGE POWER
17
Micro TLynxTM: Non-isolated DC-DC Power Modules:
2.4 – 5.5Vdc input; 0.6Vdc to 3.63Vdc output; 12A output current
Data Sheet
May 20, 2009
Example Application Circuit
Requirements:
Vin:
3.3V
Vout:
1.8V
Iout:
9A max., worst case load transient is from 6A to 9A
ΔVout:
Vin, ripple
1.5% of Vout (27mV) for worst case load transient
1.5% of Vin (50mV, p-p)
CI1
2 x 47μF/6.3V ceramic capacitor (e.g. TDK C Series)
CI2
100μF/6.3V Bulk Electrolytic
CO1
6 x 47μF/6.3V ceramic capacitor (e.g. TDK C Series)
CO2
CTune
RTune
330μF/6.3V Polymer/poscap (e.g. Sanyo Poscap)
56nF ceramic capacitor (can be 1206, 0805 or 0603 size)
33 ohms SMT resistor (can be 1206, 0805 or 0603 size)
RTrim
1kΩ SMT resistor (can be 1206, 0805 or 0603 size, recommended tolerance of 0.1%)
LINEAGE POWER
18
Data Sheet
May 20, 2009
Micro TLynxTM: Non-isolated DC-DC Power Modules:
2.4 – 5.5Vdc input; 0.6Vdc to 3.63Vdc output; 12A output current
Mechanical Outline
Dimensions are in millimeters and (inches).
Tolerances: x.x mm ± 0.5 mm (x.xx in. ± 0.02 in.) [unless otherwise indicated]
x.xx mm ± 0.25 mm (x.xxx in ± 0.010 in.)
Side View
LINEAGE POWER
19
Data Sheet
May 20, 2009
Micro TLynxTM: Non-isolated DC-DC Power Modules:
2.4 – 5.5Vdc input; 0.6Vdc to 3.63Vdc output; 12A output current
Recommended Pad Layout
Dimensions are in millimeters and (inches).
Tolerances: x.x mm ± 0.5 mm (x.xx in. ± 0.02 in.) [unless otherwise indicated]
x.xx mm ± 0.25 mm (x.xxx in ± 0.010 in.)
PIN 8
PIN 4
PIN 10
PIN 9
LINEAGE POWER
PIN
FUNCTION
1
ON/OFF
2
VIN
3
SEQ
4
GND
5
TRIM
6
VOUT
7
VS+
8
GND
9
NC
10
NC
20
Data Sheet
May 20, 2009
Micro TLynxTM: Non-isolated DC-DC Power Modules:
2.4 – 5.5Vdc input; 0.6Vdc to 3.63Vdc output; 12A output current
Packaging Details
The APTH012A0X modules are supplied in tape & reel as standard. Modules are shipped in quantities of 250 modules
per reel.
All Dimensions are in millimeters and (in inches).
Reel Dimensions:
Outside Dimensions:
Inside Dimensions:
Tape Width:
LINEAGE POWER
330.2 mm (13.00)
177.8 mm (7.00”)
44.00 mm (1.732”)
21
Micro TLynxTM: Non-isolated DC-DC Power Modules:
2.4 – 5.5Vdc input; 0.6Vdc to 3.63Vdc output; 12A output current
Surface Mount Information
Pick and Place
The Micro TLynxTM modules use an open frame
construction and are designed for a fully automated
assembly process. The modules are fitted with a label
designed to provide a large surface area for pick and
place operations. The label meets all the requirements
for surface mount processing, as well as safety
standards, and is able to withstand reflow
o
temperatures of up to 300 C. The label also carries
product information such as product code, serial
number and the location of manufacture.
Nozzle Recommendations
The module weight has been kept to a minimum by
using open frame construction. Variables such as
nozzle size, tip style, vacuum pressure and placement
speed should be considered to optimize this process.
The minimum recommended inside nozzle diameter
for reliable operation is 3mm. The maximum nozzle
outer diameter, which will safely fit within the allowable
component spacing, is 7 mm.
Lead Free Soldering
The Micro TLynxTM modules are lead-free (Pb-free)
and RoHS compliant and fully compatible in a Pb-free
soldering process. Failure to observe the instructions
below may result in the failure of or cause damage to
the modules and can adversely affect long-term
reliability.
Pb-free Reflow Profile
package is broken, the floor life of the product at
conditions of ≤ 30°C and 60% relative humidity varies
according to the MSL rating (see J-STD-033A). The
shelf life for dry packed SMT packages will be a
minimum of 12 months from the bag seal date, when
stored at the following conditions: < 40° C, < 90%
relative humidity.
300
Per J-STD-020 Rev. C
Peak Temp 260°C
250
Reflow Temp (°C)
Data Sheet
May 20, 2009
200
150
* Min. Time Above 235°C
15 Seconds
Heating Zone
1°C/Second
Cooling
Zone
*Time Above 217°C
60 Seconds
100
50
0
Reflow Time (Seconds)
Figure 47. Recommended linear reflow profile
using Sn/Ag/Cu solder.
Post Solder Cleaning and Drying
Considerations
Post solder cleaning is usually the final circuit-board
assembly process prior to electrical board testing. The
result of inadequate cleaning and drying can affect
both the reliability of a power module and the testability
of the finished circuit-board assembly. For guidance on
appropriate soldering, cleaning and drying procedures,
refer to Board Mounted Power Modules: Soldering and
Cleaning Application Note (AN04-001).
Power Systems will comply with J-STD-020 Rev. C
(Moisture/Reflow Sensitivity Classification for
Nonhermetic Solid State Surface Mount Devices) for
both Pb-free solder profiles and MSL classification
procedures. This standard provides a recommended
forced-air-convection reflow profile based on the
volume and thickness of the package (table 4-2). The
suggested Pb-free solder paste is Sn/Ag/Cu (SAC).
The recommended linear reflow profile using Sn/Ag/Cu
solder is shown in Fig. 47. Soldering outside of the
recommended profile requires testing to verify results
and performance.
MSL Rating
The Micro TLynxTM modules have a MSL rating of 2.
Storage and Handling
The recommended storage environment and handling
procedures for moisture-sensitive surface mount
packages is detailed in J-STD-033 Rev. A (Handling,
Packing, Shipping and Use of Moisture/Reflow
Sensitive Surface Mount Devices). Moisture barrier
bags (MBB) with desiccant are required for MSL
ratings of 2 or greater. These sealed packages should
not be broken until time of use. Once the original
LINEAGE POWER
22
Micro TLynxTM: Non-isolated DC-DC Power Modules:
2.4 – 5.5Vdc input; 0.6Vdc to 3.63Vdc output; 12A output current
Data Sheet
May 20, 2009
Ordering Information
Please contact your Lineage Power Sales Representative for pricing, availability and optional features.
Table 6. Device Codes
Device Code
Input
Voltage Range
Output
Voltage
Output
Current
On/Off
Logic
Connector
Type
Comcodes
APTH012A0X3-SRZ
2.4 – 5.5Vdc
0.6 – 3.63Vdc
12A
Negative
SMT
CC109130465
APTH012A0X43-SRZ
2.4 – 5.5Vdc
0.6 – 3.63Vdc
12A
Positive
SMT
CC109130473
APXH012A0X3-SRZ
2.4 – 5.5Vdc
0.6 – 3.63Vdc
12A
Negative
SMT
CC109130481
APXH012A0X43-SRZ
2.4 – 5.5Vdc
0.6 – 3.63Vdc
12A
Positive
SMT
CC109130498
Table 7. Coding Scheme
TLynx Sequencing Input voltage Output Output voltage
family
feature.
range
current
AP
T
H
T = with Seq. H = 2.4 – 5.5V
012A0
12.0A
X = w/o Seq.
X
On/Off logic
Options
ROHS
Compliance
4
-SR
Z
X=
4 = positive
programmable No entry =
output
negative
S = Surface Mount Z = ROHS6
R = Tape&Reel
Asia-Pacific Headquarters
Tel: +65 6416 4283
World Wide Headquarters
Lineage Power Corporation
3000 Skyline Drive, Mesquite, TX 75149, USA
+1-800-526-7819
(Outside U.S.A.: +1-972-284-2626)
www.lineagepower.com
e-mail: [email protected]
Europe, Middle-East and Africa Headquarters
Tel: +49 898 780 672 80
India Headquarters
Tel: +91 80 28411633
Lineage Power reserves the right to m ake changes to t he product(s) or inf ormation contained herein without notice. No liability is assumed as a result of their use or
application. No rights under any patent accompany the sale of any such product(s) or information.
© 2008 Lineage Pow er C orporation, (Mesquite, Texas) All I nternational Rights Res erved.
LINEAGE POWER
23
Document No: DS07-007 ver. 1.11
PDF name: APTH012A0X_ds.pdf