LT3150CGN Linear Technology, LT3150CGN Datasheet - Page 13

• Manufacturer Part Number: LT3150CGN
• Description: IC CTRLR REG VLDO FET 16-SSOP
• Manufacturer: Linear Technology
• Type: Positive Adjustabler

Specifications of LT3150CGN

• Number Of Outputs: 1
• Voltage - Output: 2.5 ~ 18.4 V
• Current - Supply: 12mA
• Voltage - Input: 1.5 ~ 10 V, 10 ~ 20 V
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 16-SSOP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

APPLICATIO S I FOR ATIO
Table 1. Inductor Vendors
V
sive tantalum or ceramic capacitor with a value from 1 F
to 4.7 F is appropriate.
Output Capacitor
The output capacitor choice is far more important. The
capacitor’s characteristics determines output voltage ripple.
The output capacitor must have enough capacitance to
satisfy the load under transient conditions and it must
shunt the switched component of current coming through
the diode. Output voltage ripple results because this
switched current passes through the capacitor’s finite
output impedance. The capacitor must have low imped-
ance at the 1.4MHz switching frequency of the LT3150. At
this frequency, the capacitor’s equivalent series resis-
tance (ESR) usually dominates the impedance. Choosing
a capacitor with lower ESR results in lower output voltage
ripple.
However, consider loop stability when choosing the out-
put capacitor because the LT3150 is internally compen-
sated and no access is provided to this internal
compensation. Small, low cost tantalum capacitors have
some ESR. This ESR enhances stability due to the addition
of a zero in the regulator feedback loop. Ceramic capaci-
tors are very popular, having attractive characteristics
such as near-zero ESR, small size and low cost. Replacing
the tantalum output capacitor with a ceramic unit de-
creases the phase margin, in some cases to unacceptable
levels. The addition of a phase lead capacitor and an
isolating resistor in the feedback divider network can be
used to stabilize the feedback loop, but the added compo-
nent count and cost makes the use of a tantalum output
capacitor the simpler and preferred choice.
Taiyo Yuden
Panasonic
IN1
VENDOR
Sumida
Murata
Toko
pin. ESR is not critical and in most cases, an inexpen-
[phone]
[phone]
[phone]
[phone]
[phone]
PHONE
U
U
www.panasonic.com
www.t-yuden.com
www.sumida.com
www.murata.com
www.toko.com
W
URL
U
LQH31CN100K03K
LQH32CN100K23K
LQLB2016T100M
LQLB2518T100M
PART NUMBER
LLM3225-100K
CDRH3D16100
ELJPC100KF
The boost regulator output capacitor also serves as the
V
cally close to the V
instantaneous current to slew the external MOSFET’s
gate capacitance quickly during an output load current
transient.
LINEAR REGULATOR COMPONENT SELECTION
Output Capacitors
The LT3150 linear regulator is stable with a wide range of
output capacitors (assuming the feedback loop is prop-
erly frequency compensated). However, using multiple,
low value, very low ESR ceramic capacitors (1 F to 4.7 F)
in parallel optimizes the load transient response of an
LT3150 feedback loop. As is discussed in the Frequency
Compensation section, the output capacitor value is criti-
cal because it sets the location of a pole in the feedback
loop that determines the unity-gain crossover frequency.
Therefore, the characteristics of ceramic capacitors war-
rant some discussion.
Manufacturers make ceramic capacitors with a variety of
dielectrics, each with different behavior across tempera-
ture and applied voltage. The most common dielectrics
are Z5U, Y5V, X5R and X7R. The Z5U and Y5V dielectrics
provide high C-V products in a small package at low cost,
but exhibit very strong voltage and temperature coeffi-
cients. The X5R and X7R dielectrics yield highly stable
characteristics and are more suitable for use as the output
capacitor at fractionally increased cost. The X5R and X7R
dielectrics both exhibit excellent voltage coefficient charac-
teristics. The X7R type works over a larger temperature
range and exhibits better temperature stability whereas
X5R is less expensive and is available in higher values.
IN2
input bypass capacitor. Place this capacitor physi-
INDUCTANCE
10 H
10 H
10 H
10 H
10 H
10 H
10 H
IN2
pin. This capacitor supplies the
0.44
0.21
0.25
1.3
2.2
0.5
1.7
DCR
LT3150
0.155A
0.165A
0.23A
0.21A
0.55A
0.22A
0.3A
I
SAT
13
3150f