LT3050EDDB#PBF Linear Technology, LT3050EDDB#PBF Datasheet - Page 19

• Manufacturer Part Number: LT3050EDDB#PBF
• Description: IC ADJ LDO REG 0.6V TO 44.5V 0.1A DFN-12
• Manufacturer: Linear Technology

Specifications of LT3050EDDB#PBF

• Primary Input Voltage: 45V
• Output Voltage Adjustable Range: 0.6V To 44.5V
• Dropout Voltage Vdo: 340mV
• No. Of Pins: 12
• Output Current: 100mA
• Operating Temperature Range: -40°C To +125°C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

APPLICATIONS INFORMATION
Start-up time is also affected by the presence of a feed-
forward capacitor. Start-up time is directly proportional to
the size of the feedforward capacitor and the output volt-
age, and is inversely proportional to the feedback resistor
divider current, slowing to 15ms with a 4.7nF feedforward
capacitor and a 10μF output capacitor for an output voltage
set to 5V by a 5μA feedback resistor divider.
Output Capacitance
The LT3050 regulator is stable with a wide range of output
capacitors. The ESR of the output capacitor affects stability,
most notably with small capacitors. Use a minimum output
capacitor of 2.2μF with an ESR of 3Ω or less to prevent
oscillations. If a feedforward capacitor is used with output
voltages set for greater than 24V, use a minimum output
capacitor of 4.7μF. The LT3050 is a micropower device
and output load transient response is a function of output
capacitance. Larger values of output capacitance decrease
the peak deviations and provide improved transient re-
sponse for larger load current changes. Bypass capacitors,
used to decouple individual components powered by the
LT3050, increase the effective output capacitor value. For
applications with large load current transients, a low ESR
ceramic capacitor in parallel with a bulk tantalum capacitor
often provides an optimally damped response.
Figure 4. Ceramic Capacitor DC Bias Characteristics
–100
–20
–40
–60
–80
20
0
0
2
4
DC BIAS VOLTAGE (V)
BOTH CAPACITORS ARE 16V,
1210 CASE SIZE, 10μF
6
8
Y5V
X5R
10
12
14
3050 F04
16
Give extra consideration to the use of ceramic capacitors.
Manufacturers make ceramic capacitors with a variety of
dielectrics, each with different behavior across tempera-
ture and applied voltage. The most common dielectrics
are specifi ed with EIA temperature characteristic codes
of Z5U, Y5V, X5R and X7R. The Z5U and Y5V dielectrics
provide high C-V products in a small package at low cost,
but exhibit strong voltage and temperature coeffi cients, as
shown in Figures 4 and 5. When used with a 5V regulator,
a 16V 10μF Y5V capacitor can exhibit an effective value
as low as 1μF to 2μF for the DC bias voltage applied, and
over the operating temperature range. The X5R and X7R
dielectrics yield much more stable characteristics and are
more suitable for use as the output capacitor.
The X7R type works over a wider temperature range and
has better temperature stability, while the X5R is less
expensive and is available in higher values. Care still must
be exercised when using X5R and X7R capacitors; the X5R
and X7R codes only specify operating temperature range
and maximum capacitance change over temperature.
Capacitance change due to DC bias with X5R and X7R
capacitors is better than Y5V and Z5U capacitors, but can
still be signifi cant enough to drop capacitor values below
appropriate levels. Capacitor DC bias characteristics tend
to improve as component case size increases, but expected
capacitance at operating voltage should be verifi ed.
Figure 5. Ceramic Capacitor Temperature Characteristics
–100
–20
–40
–60
–80
40
20
0
–50
BOTH CAPACITORS ARE 16V,
1210 CASE SIZE, 10μF
–25
0
TEMPERATURE (°C)
25
50
LT3050 Series
Y5V
75
X5R
100
3050 F05
125
19
3050fa