LT1764AEQ-1.5 Linear Technology, LT1764AEQ-1.5 Datasheet - Page 14

• Manufacturer Part Number: LT1764AEQ-1.5
• Description: IC REG LDO LN 3A 1.5V DDPAK-5
• Manufacturer: Linear Technology

Specifications of LT1764AEQ-1.5

• Regulator Topology: Positive Fixed
• Voltage - Output: 1.5V
• Voltage - Input: 2.7 ~ 20 V
• Voltage - Dropout (typical): 0.34V @ 3A
• Number Of Regulators: 1
• Current - Output: 3A
• Current - Limit (min): 3.1A
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: TO-263-5, D²Pak (5 leads + Tab), TO-263BA
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

APPLICATIONS
LT1764A Series
Ceramic Capacitors
Extra consideration must be given to the use of ceramic
capacitors. Ceramic capacitors are manufactured with a
variety of dielectrics, each with different behavior over
temperature and applied voltage. The most common
dielectrics used are Z5U, Y5V, X5R and X7R. The Z5U and
Y5V dielectrics are good for providing high capacitances
in a small package, but exhibit strong voltage and tem-
perature coefficients as shown in Figures 3 and 4. When
used with a 5V regulator, a 10µF Y5V capacitor can exhibit
an effective value as low as 1µF to 2µF over the operating
temperature 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 available in higher values.
14
Figure 3. Ceramic Capacitor DC Bias Characteristics
–100
–20
–40
–60
–80
20
0
0
Table 2. PC Trace Resistors
0.5oz C
1.0oz C
2.0oz C
2
U
4
DC BIAS VOLTAGE (V)
U
U
U
INFORMATION
BOTH CAPACITORS ARE 16V,
1210 CASE SIZE, 10µF
6
U
Width
Length
Width
Length
Width
Length
8
Y5V
X5R
10
W
12
14
0.011
0.006
0.006
0.102
0.110
0.224
1764 F10
16
10mΩ
"
"
"
"
"
"
(0.28mm)
(0.15mm)
(0.15mm)
U
(2.6mm)
(2.8mm)
(5.7mm)
Voltage and temperature coefficients are not the only
sources of problems. Some ceramic capacitors have a
piezoelectric response. A piezoelectric device generates
voltage across its terminals due to mechanical stress,
similar to the way a piezoelectric accelerometer or micro-
phone works. For a ceramic capacitor the stress can be
induced by vibrations in the system or thermal transients.
“FREE” Resistance with PC Traces
The resistance values shown in Table 1 can easily be made
using a small section of PC trace in series with the output
capacitor. The wide range of noncritical ESR makes it easy
to use PC trace. The trace width should be sized to handle
the RMS ripple current associated with the load. The
output capacitor only sources or sinks current for a few
microseconds during fast output current transitions. There
0.011
0.006
0.006
0.450
0.204
0.220
Figure 4. Ceramic Capacitor Temperature Characteristics
20mΩ
"
"
"
"
"
"
(0.28mm)
(0.15mm)
(0.15mm)
(11.4mm)
(5.2mm)
(5.6mm)
–100
–20
–40
–60
–80
40
20
0
–50
BOTH CAPACITORS ARE 16V,
1210 CASE SIZE, 10µF
–25
0
TEMPERATURE (°C)
0.011
0.006
0.006
0.307
0.330
0.670
25
30mΩ
"
"
"
"
"
"
(0.28mm)
(0.15mm)
(0.15mm)
(7.8mm)
(8.4mm)
(17mm)
50
Y5V
75
X5R
100
1764 F11
125
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