Datasheet

PTN78020W
PTN78020H
SLTS228C – DECEMBER 2004– REVISED AUGUST 2011 www.ti.com
Table 6. Recommended Input/Output Capacitors (PTN78020H)
CAPACITOR CHARACTERISTICS QUANTITY
85°C
CAPACITOR VENDOR/
EQUIVALENT
VENDOR
WORKING MAXIMUM PHYSICAL
COMPONENT
VALUE SERIES INPUT OUTPUT
NUMBER
VOLTAGE RIPPLE SIZE
SERIES
(µF) RESISTANCE BUS BUS
(V) CURRENT (mm)
(ESR) (Ω)
(mArms)
Panasonic FC( Radial) 35 330 0.068 1050 10 × 16 1 1 EEUFC1V331 (V
I
< 30 V)
FK (SMD) 50 330 0.12 900 12,5 × 13,5 1
(1)
1 EEVFK1H331Q
LXZ 35 220 0.09 760 10 × 12,5 2 LXZ35VB2231M10X12LL
1
(1)
(V
I
< 30 V)
MVY(SMD) 35 220 0.15 670 10 × 10 1 2 MVY35VC221M10X10TP
(V
I
< 30 V)
Nichicon UWG (SMD) 35 330 0.15 670 10 × 10 1 1 UWG1V331MNR1GS
(V
I
< 30 V)
Sanyo Os-Con SP (SMD 20 180 0.032 4280 10 ×10.5 2
(1)
≤ 2 20SP180M (V
I
~ V
O
≤ 16 V)
TDK X7R Ceramic 25 2.2 0.002 >1000 3225 ≥ 8
(2)
1 C3225X7R1E225KT/MT
(V
O
≤ 20 V)
Murata X7R Ceramic 25 2.2 0.002 >1000 3225 ≥ 8
(2)
1 GRM32RR71E225K
(V
O
≤ 20 V)
Kemet X7R Ceramic 25 2.2 0.002 >1000 3225 ≥ 8
(2)
1 C1210C225K3RAC
(V
O
≤ 20 V)
AVX X7R Ceramic 25 2.2 0.002 >1000 32225 ≥ 8
(2)
1 C12103C225KAT2A
(V
O
≤ 20 V)
Murata X7R Ceramic 50 4.7 0.002 >1000 3225 ≥ 4 1 GRM32ER71H475KA88L
TDK X7R Ceramic 50 3.3 0.002 >1000 3225 ≥ 6 1 CKG45NX7R1H335M
Murata Radial Through-hole 50 3.3 0.004 >1000 12,5 H x ≥ 6 1 RPER71H3R3KK6F03
12,5 W x
4 D
Kemet Radial Through-hole 50 4.7 0.002 >1000 5,08 × 7,62 ≥ 4
(3)
1 C350C475K5R5CA
× 9,14 H
(1) The voltage rating of the input capacitor must be selected for the desired operating input voltage range of the regulator. To operate the
regulator at a higher input voltage, select a capacitor with the next higher voltage rating.
(2) The maximum rating of the ceramic capacitor limits the regulator operating input voltage to 20 V. Select a alternative ceramic
component to operate at a higher input voltage.
(3) A total capacitance of 2 µF is an acceptable replacement value for a single 2.2-µF ceramic capacitor
Output Voltage Sense
An external output voltage sense improves the load regulation performance of the module by enabling it to
compensate for any IR-voltage drop between the module and the load circuit. This voltage drop is caused by the
flow of current through the resistance in the printed-circuit board connections.
To use the output voltage sense feature, simply connect the V
O
Sense input (pin 5) to V
O
, close to the device
that draws the most supply current. If an external voltage sense is not desired, the V
O
Sense input may be left
open circuit. An internal resistor (15 Ω or less), connected between this input and V
O
, ensures that the output
remains in regulation.
With V
O
Sense connected, the difference between the voltage measured directly between the V
O
and GND, and
that measured from V
O
Sense to GND, represents the amount of IR-voltage drop being compensated by the
regulator. This should be limited to a maximum of 0.3 V.
Note: The external voltage sense is not designed to compensate for the forward drop of nonlinear or
frequency-dependent components that may be placed in series with the regulator's output. Examples include
OR-ing diodes, filter inductors, ferrite beads, and fuses. When these components are enclosed by the external
sense connection, they are effectively placed inside the regulation control loop. This can adversely affect the
stability of the module.
Undervoltage Lockout
The undervoltage lockout (UVLO) circuit prevents the module from attempting to power up until the input voltage
is above the UVLO threshold. This is to prevent the module from drawing excessive current from the input source
at power up. Below the UVLO threshold, the module is held off.
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