LT3008ITS8-5#TRMPBF Linear Technology, LT3008ITS8-5#TRMPBF Datasheet - Page 13

• Manufacturer Part Number: LT3008ITS8-5#TRMPBF
• Description: IC REG LDO 5.0V 20MA TSOT23-8
• Manufacturer: Linear Technology

Specifications of LT3008ITS8-5#TRMPBF

• Regulator Topology: Positive Fixed
• Voltage - Output: 5V
• Voltage - Input: Up to 45V
• Voltage - Dropout (typical): 0.3V @ 20mA
• Number Of Regulators: 1
• Current - Output: 20mA
• Current - Limit (min): 22mA
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: TSOT-23-8, TSOT-8
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

APPLICATIONS INFORMATION
Because the ADJ pin is relatively high impedance (de-
pending on the resistor divider used), stray capacitances
at this pin should be minimized. Special attention should
be given to any stray capacitances that can couple ex-
ternal signals onto the ADJ pin, producing undesirable
output transients or ripple.
Extra care should be taken in assembly when using high
valued resistors. Small amounts of board contamination
can lead to signifi cant shifts in output voltage. Appropriate
post-assembly board cleaning measures should be
implemented to prevent board contamination. If the
board is to be subjected to humidity cycling or if board
cleaning measures cannot be guaranteed, consideration
should be given to using resistors an order of magnitude
smaller than in Table 1 to prevent contamination from
causing unwanted shifts in the output voltage. A fi xed
voltage option in the LT3008 series will not need these
special considerations.
Output Capacitance and Transient Response
The LT3008 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. The LT3008 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 response for
larger load current changes.
Figure 3. 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
3008 F03
16
Give extra consideration to the use of ceramic capacitors.
Manufacturers make ceramic capacitors with a variety of
dielectrics, each with different behavior across temperature
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 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 temperature range. The X5R and
X7R dielectrics yield 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 available in higher values.
One must still exercise care 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.
Voltage and temperature coeffi cients are not the only
sources of problems. Some ceramic capacitors have a
Figure 4. 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
LT3008 Series
50
Y5V
75
X5R
100
3008 F04
125
13
3008fb