LTC3704EMS Linear Technology, LTC3704EMS Datasheet - Page 22

• Manufacturer Part Number: LTC3704EMS
• Description: IC INV SYNC 5.2V 50MA 10MSOP
• Manufacturer: Linear Technology
• Type: Invertingr

Specifications of LTC3704EMS

• Internal Switch(s): No
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: -5.2V
• Current - Output: 50mA
• Frequency - Switching: 50kHz ~ 1MHz
• Voltage - Input: 2.5 ~ 36 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 10-MSOP, Micro10™, 10-uMAX, 10-uSOP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Power - Output: -

APPLICATIO S I FOR ATIO
LTC3704
The capacitor used was a TDK 47μF, 16V X5R-dielectric
ceramic (C5750X5R1C476M), mainly because of its low
ESR (2.4mΩ) and high RMS current capability.
8. The peak-to-peak output ripple is:
As a first try, a TDK 100μF, 6.3V X5R-dielectric ceramic
capacitor was chosen (C5750X5R0J107M). This capaci-
tor has a very low 1.6mΩ of ESR. As a result, the peak-to-
peak output ripple voltage is:
22
100mV/DIV
ΔV
⎡
⎢
⎣
10mV/DIV
V
V
I
OUT
–
OUT
OUT
I
L2
1A/DIV
1A/DIV
ESR
O P P
(AC)
(DC)
(AC)
(DC)
(
−
Figure 20. Load Step Response at V
for the Circuit in Figure 15
Figure 18. Output Ripple Voltage and
Inductor Current for the Circuit in Figure 15
V
I
V
–
OUT
IN
IN
)
8
= 5V
= 15V
=
= –2V
• •
1
f C
1
–
2A
D
U
f
O
0.5A
MAX
⎤
⎥
⎦
250μs/DIV
U
•
1μs/DIV
V
L
O
2
W
IN
3704 F18
3704 F20
= 15V
U
This ripple voltage calculation also assumes no coupling
between the inductors, making the 13.7mV number very
conservative.
Figure 15 illustrates the same basic application shown in
Figure 1, with the added features of soft-start and
undervoltage lockout on the input supply. Figures 16
through 21 illustrate the measured performance for this
converter. The peak efficiency is 87% at a load current of
2A and the peak-to-peak output ripple is less than 10mV.
Figures 19 and 20 illustrate the load step response at 5V
and 15V input, and Figure 21, the start-up characteristics
with a resistive load.
100mV/DIV
ΔV
⎡
⎢
⎣
V
I
OUT
OUT
– .
1A/DIV
1V/DIV
1A/DIV
0 0016
O P P
V
(AC)
(DC)
I
OUT
OUT
(
Figure 21. Soft-Start for the Circuit in Figure 15
−
Figure 19. Load Step Response at V
for the Circuit in Figure 15
V
V
IN
IN
)
= 5V
= 5V
=
–
1 0 5
8 300 100
300
– .
2A
•
0.5A
k
I
OUT
k
1
•
•
3 5
V
250μs/DIV
5 0
OUT
1ms/DIV
.
.
μ
μ
⎤
⎥ =
⎦
13 7
.
mV
IN
3704 F19
3704 F21
= 5V
3704fb