SC1112STRT Semtech, SC1112STRT Datasheet - Page 17

• Manufacturer Part Number: SC1112STRT
• Manufacturer: Semtech

Specifications of SC1112STRT

• Lead Free Status / RoHS Status: Compliant

Adjustable Output Voltage Option
The adjustable output voltage option does not have an
internal resistor divider. The adjust pin connects directly to
the inverting input of the error amplifier, and the
output voltage is set using external resistors (please
refer to Figure 2). In this case, the adjust pin sources a
nominal 0.5µA, so the resistor values should be selected
to allow 50µA to flow through the divider. Again, a target
value
calculated:
The output voltage can be calculated as follows:
The maximum output voltage that can be obtained from
the adjustable option is determined by the input supply
voltage and the R
external MOSFET. Assuming that the MOSFET gate
threshold voltage is sufficiently low for the output
voltage chosen and a worst-case drive voltage of 9V, V
is given by:
RB
Applications Infomation (Cont.)
V
V
POWER MANAGEMENT
OUT
OUT
2006 Semtech Corp.
. 1
50
(
MAX
200
. 1
200
A
V
for
)
1
VTTIN
RA
RB
DS(ON)
RB
(
and gate threshold voltage of the
MIN
0
5 .
)
A
(maximum)
VTT SELECT Signal
5VSTBY
ADJGATE
ADJSEN
CAP-
CAP+
FC
DELAY
PWRGD
I
RA
OUT
Figure 1: Adjusting The Output Voltage of VTT or AGP
SC1112
(
MAX
AGPGATE
VTTGATE
AGPSEN
AGPSEL
VTTSEN
VTTSEL
VTTIN
GND
)
R
DS
can
C3
0.1u
(
ON
AGP SELECT Signal
)(
OUT(MAX)
MAX
C19
330u
be
)
Q1
330u
17
C8
C9
0.1u
C2
330u
C18
Q3
0.1u
C13
R1
R2
C16
330u
C6
330u
C14
330u
330u
C12
C1
10u
C17
0.1u
RA
RB
+3.3V
+5V STBY
AGP
VTT
Q2
Figure 2
1K
R1
POWER GOOD
VTT
0.1u
22n
1u
C5
C10
C11
www.semtech.com
SC1112
5VSTBY
ADJGATE
ADJSEN
CAP-
CAP+
FC
DELAY
PWRGD
SC11