LTC3631EMS8E-5#TRPBF Linear Technology, LTC3631EMS8E-5#TRPBF Datasheet - Page 13
LTC3631EMS8E-5#TRPBF
Manufacturer Part Number
LTC3631EMS8E-5#TRPBF
Description
IC CONV STP-DWN SYNC 5.0V 8-MSOP
Manufacturer
Linear Technology
Type
Step-Down (Buck)r
Datasheet
1.LTC3631EMS8E-5PBF.pdf
(22 pages)
Specifications of LTC3631EMS8E-5#TRPBF
Internal Switch(s)
Yes
Synchronous Rectifier
Yes
Number Of Outputs
1
Voltage - Output
5V
Current - Output
100mA
Voltage - Input
4.5 ~ 45 V
Operating Temperature
-40°C ~ 125°C
Mounting Type
Surface Mount
Package / Case
8-MSOP Exposed Pad, 8-HMSOP, 8-eMSOP
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Power - Output
-
Frequency - Switching
-
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
applicaTions inForMaTion
Output Voltage Programming
For the adjustable version, the output voltage is set by
an external resistive divider according to the following
equation:
The resistive divider allows the V
of the output voltage as shown in Figure 6. Output voltage
can range from 0.8V to V
To minimize the no-load supply current, resistor values in
the megohm range should be used; however, large resistor
values should be used with caution. The feedback divider
is the only load current when in shutdown. If PCB leak-
age current to the output node or switch node exceeds
the load current, the output voltage will be pulled up. In
normal operation, this is generally a minor concern since
the load current is much greater than the leakage. The
increase in supply current due to the feedback resistors
can be calculated from:
Run Pin with Programmable Hysteresis
The LTC3631 has a low power shutdown mode controlled
by the RUN pin. Pulling the RUN pin below 0.7V puts the
LTC3631 into a low quiescent current shutdown mode
(I
Q
V
ΔI
~ 3µA). When the RUN pin is greater than 1.2V, the
OUT
VIN
= 0.8V • 1+
=
R1+ R2
Figure 6. Setting the Output Voltage
V
OUT
LTC3631
•
R2
R1
GND
V
V
FB
IN
V
OUT
.
IN
V
OUT
FB
R1
R2
3631 F06
pin to sense a fraction
The RUN pin can alternatively be configured as a precise
undervoltage lockout (UVLO) on the V
resistive divider from V
parator nominally provides 10% hysteresis when used in
this method; however, additional hysteresis may be added
with the use of the HYST pin. The HYST pin is an open-
drain output that is pulled to ground whenever the RUN
comparator is not tripped. A simple resistive divider can
be used as shown in Figure 8 to meet specific V
requirements.
Specific values for these UVLO thresholds can be computed
from the following equations:
controller is enabled. Figure 7 shows examples of con-
figurations for driving the RUN pin from logic.
Rising V
Falling V
V
SUPPLY
IN
IN
Figure 8. Adjustable Undervoltage Lockout
UVLO Threshold = 1.21V • 1+
UVLO Threshold = 1.10V • 1+
Figure 7. RUN Pin Interface to Logic
RUN
LTC3631
V
IN
R1
R2
R3
IN
to ground. The RUN pin com-
RUN
HYST
LTC3631
3631 F08
V
IN
4.7M
LTC3631
IN
RUN
supply with a
LTC3631
R2
R1
R2 + R3
3631 F07
IN
R1
13
voltage
3631fc