Semtech SC21150 User manual

© 2015 Semtech Corporation
POWER MANAGEMENT
1
SC21150 EVB Guide
Evaluation Board
User’s Guide
Description
The SC21150 is a 5V input monolithic regulator with 1.2A
output current capability. It has an input voltage range of
2.3V to 5.5V and a reference voltage of 0.8V. The user can
use an external resistor divider to program the output
voltage. SC21150 uses an improved Adaptive-On Time
(AOT) architecture to provide excellent light-load effi-
ciency by lowering the switching frequency, while
maintaining a relative constant switching frequency at
heavy load conditions.
This guide contains information on how to use the EVB
and should be used in conjunction with the datasheet.
The datasheet contains detailed information including the
electrical characteristics, operating modes, circuit design
procedures, a typical application circuit, and other appli-
cation information.
This EVB Guide is applicable to the Rev 1 pcb layout.
Revision 1.0
This guide is intended to help the user become familiar
with the features of the device. This EVB has many test
points and jumpers which allow the user to measure
various parameters and circuit capabilities. Users can
eliminate these test points and jumpers to simplify the
circuit for a specic application.
Feature Content
Jumper Settings
Evaluation Instruction
Evaluation Board Schematic
Bill of Materials and Key Components
Layout Drawings
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•
•
•
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SC21150 EVB

SC21150 EVB Guide
2
Jumper Settings
VOUT Ripple Measurement
VIN Measurement
J2 — VOUT Banana Jacks
JP1 — Enable Jumper
J1 — VIN Banana Jacks
VOUT Regulation Measurement
Switching Node (LX) Monitor
ON — connect to ON
OFF — connect to OFF
VIN Remote Sense
(for tight VIN
supply regulation)
FPWM test point
JP2— FPWM Input Select
FPWM — connect pins 1-2
Power-Save(PFM) — connect pins 2-3

SC21150 EVB Guide
3
Jumper Settings (Continued)
Please read the schematics and examine the evalua-
tion board to get familiar with the EVB and its con-
nectors and jumpers before making any connections.
J1 is for connecting an to input power supply. J2 is for
connecting the output to an electronic load or a load
resistor.
Make sure the VIN supply is o. Then connect the ex-
ternal VIN supply to J1 (+ and -) with correct polarity.
If the VIN supply has a remote sense, the remote sense
lines can be connect to the VIN and PGND paired test
points respectively.
Connect an electronic load to J2 with correct polarity.
Make sure the load current is set at 0A.
DVMs (Digital Voltage Meters) can be connected to
pairs of test points: (VIN, PGND) for the input voltage
monitor and (VOUT, PGND) for the output voltage
monitor.
“LX”is for an oscilloscope to monitor the LX switching
node. The LX test point has a PGND pin nearby for
easy connection.
For best accuracy, VOUT ripple should be monitored
by an oscilloscope, using closely paired test points
(VOUT, PGND). Use short leads for both the probe tip
and probe ground to reduce noise pick-up between
the VOUT measurement and the oscilloscope.
Set jumper JP1 to the OFF position.
Set JP2 with the jumper in the pins 1-2 position. This
connects the FPWM input to the VIN supply via the
on-board 10k ohm pull-up resistor. Selecting the
1-2 position will set the FPWM input high and cause
forced continuous mode operation at all load condi-
tions.
1.
2.
3.
4.
5.
6.
7.
8.
9.
Evaluation Instructions
Turn on the VIN external power supply and slowly in-
crease the voltage to 5V.
Put JP1 in the ON position pins 1-2. The output
(VOUT) should have an output voltage established.
Use a DVM to monitor the output voltage.
Vary the load over the load range from 0A to 1.2A; the
output voltage should stay in regulation.
An oscilloscope can be used to monitor the LX node
and VOUT voltage while the regulator is in operation.
Switching JP1 position between on and o, the soft
start and shutdown behavior of the regulator can be
monitored.
The FPWM jumper JP2 is used to select either FPWM
(Forced PWM operation, connect pins 1-2) or Power-
save (PFM Pulse Frequency Modulation, connect pins
2-3). Note that at moderate and high load conditions,
the IC will go into FPWM operation regardless of the
FPWM input setting.
1.
2.
3.
4.
5.
6.

SC21150 EVB Guide
4
5 5
4 4
3 3
2 2
1 1
D D C C B B A A
ENABLE
BANANA JACK INPUT/OUTPUT
Vout feedback
AUX
ENR AUXR
LX
VOUT
FB
EN
VOUTVIN
VIN
VOUT
VIN
EN
VIN
AUX
AUX
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C7 10u
J1
VIN
1 2
MH1
C11
np
+
C10 np
TP13 VOUT
TP9
LX
R4 0
R1 10k
MH3
TP12
VIN
TP1 VIN
C5
4.7u
C2 np
TP6 PGND
TP4 AUX
L1 0.47u
C9 np
R5 np
MH4MH2
C8 np
JP1
EN
1 2 3
C1 np
TP17
FB
TP15
PGND
TP7
PGND TP16
PGND
+
C3 np
TP10
VIN
TP5 PGND
TP2 VOUT
R3 np
TP14 BODE
C4
np
TP3
EN R2
10k
J2
VOUT
1 2
C6 np
U1
SC21150
GND
A1
LX
B1
FB
C1
VIN A2
AUX B2
EN C2
JP2
EN
1 2 3
Evaluation Board Schematic
Note: the default schematic is shown. Component values may vary to change the output voltage or EVB performance.
Refer to the Schematic or BOM le provided with the EVB.

SC21150 EVB Guide
5
Bill of Materials and Key Components(1)
Item Qty Reference(2) Value Part Number Manufacturer PCB Foot Print
1 1 C5 4.7μF/10V/X5R Murata SM/C 0805
2 1 C7 10μF/10V/X5R Murata SM/C 0805
3 2 J1, J2 108-0740-001 (banana jacks) Johnson Components BJACK_PAIR_NI
4 1 L1 0.47μH PFL2010 Coilcraft
5 2 JP1, JP2 3 pin Header 22-03-2031 (3-pin header) Molex TH/CON_3_100
6 1 R5 np SM/R 0603
71 R3
(3) np SM/R 0603
8 1 R4 0 ERJ-3EKF0R00V Panasonic SM/R 0603
9 1 C11 np Murata SM/C 0603
10 1 C2 np Murata SM/C 0603
11 2 R1, R2 10k ERJ-3EKF1001V Panasonic SM/R 06903
12 11 TP1-7,TP9, TP12-13,
TP15-16
3103-2-00-21-00-00-08-0
(gold pin)
Mill-Max TEST PT .100
13 1 U1 SC21150 SC21150ACSTRT Semtech see datasheet
Notes:
(1) The BOM for the EVB may dier from the above components due to dierent power stage inductor, capacitor, and VIN/VOUT requirements.
Refer to the schematic or BOM le provided with the EVB.
(2) Critical components are in bold type.
(3) R3 is shorted by pcb copper. R3 can be used for closed-loop Bode plot measurements. To measure closed-loop Bode performance, cut the
copper trace for R3 and install a low-ohm resistor (10 to 50 ohms) for R3. Use test points VOUT and TP14 to perform typical Bode plot tests.
The VOUT test points are provided as gold pins; test point TP14 is a plated via hole in the pcb.
VOUT (V) 1V 1.2V 1.5V 1.8V 2.5V 3.3V
L1 (μH) 0.47
C7 (μF) 10μF, 10V, X5R
R4(kΩ)24.9 49.9 86.6 121 210 309
R5(kΩ)100 100 100 100 100 100
C11(pF) 22 22 22 22 22 22
Recommended Components for Dierent VOUT

SC21150 EVB Guide
6
Layout Drawings — Top Component and Silk Screen

SC21150 EVB Guide
7
Layout Drawings — Bottom Component and Silk Screen

Semtech Corporation
Power Management Products Division
200 Flynn Road, Camarillo, CA 93012
Phone: [phone] Fax: [phone]
www.semtech.com
Contact Information
SC21150 EVB Guide
8
© Semtech 2015
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