PTH04T221W_15 Datasheet, PDF (15/38 Pages) Texas Instruments – 16-A, 2.2-V to 5.5-V INPUT, NON-ISOLATED, WIDE-OUTPUT, ADJUSTABLE POWER MODULE WITH TURBOTRANS™

PTH04T220W, PTH04T221W
www.ti.com ................................................................................................................................................... SLTS275D – DECEMBER 2006 – REVISED JULY 2009
Designing for Fast Load Transients
The transient response of the dc/dc converter has been characterized using a load transient with a di/dt of
2.5A/µs. The typical voltage deviation for this load transient is given in the Electrical Characteristics table using
the minimum required value of output capacitance. As the di/dt of a transient is increased, the response of a
converter’s regulation circuit ultimately depends on its output capacitor decoupling network. This is an inherent
limitation with any dc/dc converter once the speed of the transient exceeds its bandwidth capability.
If the target application specifies a higher di/dt or lower voltage deviation, the requirement can only be met with
additional low ESR ceramic capacitor decoupling. Generally, with load steps greater than 100A/µs, adding
multiple 10µF ceramic capacitors plus 10×1µF, and numerous high frequency ceramics (≤0.1µF) is all that is
required to soften the transient higher frequency edges. The PCB location of these capacitors in relation to the
load is critical. DSP, FPGA and ASIC vendors identify types, location and amount of capacitance required for
optimum performance. Low impedance buses, unbroken PCB copper planes, and components located as close
as possible to the high frequency devices are essential for optimizing transient performance.
Table 3. Input/Output Capacitors⁽¹⁾
Capacitor Characteristics
Capacitor Vendor,
Type Series (Style)
Working
Voltage
(V)
Value
(µF)
Max
ESR
at 100
kHz
(mΩ)
Max
Ripple
Current
at 85°C
(Irms)
(mA)
Physical
Size (mm)
Panasonic
SP series (UE)
6.3
220
15
3000
7,3×4,3
FC (Radial )
6.3
390 117
555
8 X 11,5
FK (SMD)
6.3
470 160
600
10 X 10,2
United Chemi-Con
PTB, Poly-Tantalum(SMD) 6.3
330
25
2600 7,3×4,3×2,8
LXZ, Aluminum (Radial)
6.3
680 120
555
8 X 12
PS, Poly-Alum (Radial)
6.3
390
12
4770
8 X 11,5
PT Poly-Tantalum (SMD)
6.3
330
40
3000
7,3×4,3
MVY, Aluminum SMD)
10
680 150
670
10 × 10
PXA, Poly-Alum (Radial)
10 V
330
14
4420
8 × 12,2
Nichicon, Aluminum
WG (SMD)
10
470 150
670
10 × 10
HD (Radial)
10
470
72
760
8 X 11,5
Panasonic, Poly-Aluminum
SE Series (SMD)
2.0
560
5
4000 7,3×4,3×4,2
Input
Bus
2
1
1
1
1
1
1
1
1
1
1
N/R ⁽⁵⁾
Quantity
Output Bus ⁽²⁾
No
Turbo-
Trans
Turbo-
Trans
Capacitor
Type ⁽³⁾
Vendor Part No.
1≤ 2
≥1
≥1
B ≥ 1⁽³⁾
N/R ⁽⁴⁾
N/R ⁽⁴⁾
EEFUE0J221R
EEUFC0J391
EEVFK0J471P
1≤3
1
≤1
1
1
1≤2
C ≥ 2⁽³⁾
N/R ⁽⁴⁾
B ≥ 2⁽³⁾
N/R ⁽⁴⁾
B ≥ 2⁽³⁾
B ≥ 1⁽³⁾
6PTB337MD6TER
LXZ6.3VB681M8X12LL
6PS390MH11
6PT337MD8TER
MVY10VC681MJ10TP
PXA10VC331MH12
1
1
N/R ⁽⁶⁾
N/R ⁽⁴⁾
N/R ⁽⁴⁾
UWG1A471MNR1GS
UHD1A471MPR
B ≥ 2⁽³⁾ EEFSE0J391R(V_O≤ 1.6V)⁽⁷⁾
(1) Capacitor Supplier Verification
Please verify availability of capacitors identified in this table. Capacitor suppliers may recommend alternative part numbers because of
limited availability or obsolete products.
RoHS, Lead-free and Material Details
See the capacitor suppliers regarding material composition, RoHS status, lead-free status, and manufacturing process requirements.
Component designators or part number deviations can occur when material composition or soldering requirements are updated.
(2) Additional output capacitance must include the required 100 µF of ceramic type.
(3) Required capacitors with TurboTrans. See the TurboTrans Application information for Capacitor Selection
Capacitor Types:
a. Type A = (100 < capacitance × ESR ≤ 1000)
b. Type B = (1,000 < capacitance × ESR ≤ 5,000)
c. Type C = (5,000 < capacitance × ESR ≤ 10,000)
(4) Aluminum Electrolytic capacitor not recommended for the TurboTrans due to higher ESR × capacitance products. Aluminum and higher
ESR capacitors can be used in conjunction with lower ESR capacitance.
(5) N/R – Not recommended. The voltage rating does not meet the minimum operating limits.
(6) N/R – Not recommended. The ESR value of this capacitor is below the required minimum when not using TurboTrans.
(7) The voltage rating of this capacitor only allows it to be used for output voltage that is equal to or less than 80% of the working voltage.
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