LT1761IS5-2.5#PBF Linear Technology, LT1761IS5-2.5#PBF Datasheet - Page 16

• Manufacturer Part Number: LT1761IS5-2.5#PBF
• Description: IC, LDO VOLT REG, 2.5V, 0.1A, 5-TSOT-23
• Manufacturer: Linear Technology

Specifications of LT1761IS5-2.5#PBF

• Primary Input Voltage: 3.5V
• Output Voltage Fixed: 2.5V
• Dropout Voltage Vdo: 300mV
• No. Of Pins: 5
• Output Current: 100mA
• Operating Temperature Range: -40°C To +125°C
• Termination Type: SMD
• Msl: MSL 1 - Unlimited
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

APPLICATIONS INFORMATION
LT1761 Series
Output Capacitance and Transient Response
The LT1761 regulators are designed to be stable with a
wide range of output capacitors. The ESR of the output
capacitor affects stability, most notably with small capaci-
tors. A minimum output capacitor of 1μF with an ESR of
3Ω or less is recommended to prevent oscillations. The
LT1761-X is a micropower device and output transient
response will be a function of output capacitance. Larger
values of output capacitance decrease the peak deviations
and provide improved transient response for larger load
current changes. Bypass capacitors, used to decouple
individual components powered by the LT1761-X, will
increase the effective output capacitor value. With larger
capacitors used to bypass the reference (for low noise
operation), larger values of output capacitors are needed.
For 100pF of bypass capacitance, 2.2μF of output capaci-
tor is recommended. With a 330pF bypass capacitor or
larger, a 3.3μF output capacitor is recommended. The
shaded region of Figure 2 defi nes the region over which
the LT1761 regulators are stable. The minimum ESR
needed is defi ned by the amount of bypass capacitance
used, while the maximum ESR is 3Ω.
Extra consideration must be given to the use of ceramic
capacitors. Ceramic capacitors are manufactured with a
variety of dielectrics, each with different behavior across
temperature and applied voltage. The most common
dielectrics used are specifi ed with EIA temperature char-
acteristic codes of Z5U, Y5V, X5R and X7R. The Z5U and
Y5V dielectrics are good for providing high capacitances
in a small package, but they tend to have strong voltage
16
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
1
C
BYP
C
BYP
= 0
= 100pF
OUTPUT CAPACITANCE (μF)
C
BYP
Figure 2. Stability
2
STABLE REGION
= 330pF
C
BYP
3
> 3300pF
4
5 6 7 8 9
1761 F02
10
and temperature coeffi cients as shown in Figures 3 and 4.
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 tempera-
ture range. The X5R and X7R dielectrics result in more
stable characteristics and are more suitable for use as the
output capacitor. The X7R type has better stability across
temperature, while the X5R is less expensive and is avail-
able 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. Capaci-
tor DC bias characteristics tend to improve as component
case size increases, but expected capacitance at operating
voltage should be verifi ed.
Figure 4. Ceramic Capacitor Temperature Characteristics
Figure 3. Ceramic Capacitor DC Bias Characteristics
–100
–100
–20
–40
–60
–80
–20
–40
–60
–80
20
40
20
0
0
–50
0
BOTH CAPACITORS ARE 16V,
1210 CASE SIZE, 10μF
–25
2
4
DC BIAS VOLTAGE (V)
0
TEMPERATURE (°C)
BOTH CAPACITORS ARE 16V,
1210 CASE SIZE, 10μF
6
25
8
Y5V
X5R
50
10
Y5V
75
12
X5R
100
14
1761 F03
1761 F04
125
16
1761sff