SC4501STDEVB Semtech, SC4501STDEVB Datasheet - Page 13
SC4501STDEVB
Manufacturer Part Number
SC4501STDEVB
Description
EVALUATION BOARD
Manufacturer
Semtech
Datasheet
1.SC4501MLTRT.pdf
(21 pages)
Specifications of SC4501STDEVB
Silicon Manufacturer
Semtech
Application Sub Type
Step Up Switching Regulator
Kit Application Type
Power Management - Voltage Regulator
Silicon Core Number
SC4501
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
with
Example: Increase the turn on voltage of a V
converter from 1.4V to 2.75V.
Using V
The resulting UVLO hysteresis is:
Application Information
POWER MANAGEMENT
2005 Semtech Corp.
R
V
HYS
3
V
L
Figure 7. Programmable Hysteretic UVLO Circuit
H
150
= 2.75V and R
I
1
HYS
4 .
R3
R4
K
R
V
3
.
.
4
SC4501
SHDN
6 .
3
A
4
1.1V
150
= 100K in (12),
6/8
IN
I HYS
4.6 A
K
+
-
SWITCH CLOSED
C6
Figure 8. Simplified Block Diagram of a Boost Converter
WHEN Y = “1”
V
IN
. 0
COMPARATOR
COMP
R3
69
C4
V
.
RO
IN
= 3.3V boost
Gm
Y
POWER
STAGE
REFERENCE
+
-
VOLTAGE
1.242V
FB
13
The turn off voltage is:
Frequency Compensation
Figure 8 shows the equivalent circuit of a boost converter
using the SC4501. The output filter capacitor and the load
form an output pole at frequency:
where C
equivalent load resistance.
The zero formed by C
(ESR) is neglected due to low ESR of the ceramic output
capacitor.
There is also a right half plane (RHP) zero at angular
frequency:
I
Figure 1(a) as an example,
OUT
z2
R
. Using the 5V to 12V boost regulator (1.35MHz) in
V
decreases with increasing duty cycle D and increasing
L
OUT
p
Z
C5
2
2
V
2
H
R
R1
R2
. 0
is the output capacitor and
OUT
V
I 2
5
OUT
74
V
V
HYS
OUT
1
ESR
L
C
I
C2
A
OUT
2
D
. 2
6
2
8 .
R OUT
75
2
R
and its equivalent series resistance
OUT
V OUT
2
. 0
C
2
69
. 2
06
V
R
1
OUT
www.semtech.com
4 .
SC4501
V
.
V
I
OUT
OUT
is the
(13)
(14)