19-5661; Rev 0; 12/10
MAX16974 Evaluation Kit
General Description
The MAX16974 evaluation kit (EV kit) provides a proven
design to evaluate the MAX16974 high-voltage, 2.2MHz,
2A automotive step-down controller with low operating
current. It is designed to operate with 3.5V to 28V input
voltages, while using only 35µA quiescent current at no
load. The switching frequency is adjustable from 220kHz
to 2.2MHz and the output voltage is pin selectable at 5V
fixed or 1V to 10V adjustable. This EV kit is initially set up
to operate at 2.2MHz with a 5V output.
The EV kit PCB comes with a MAX16974AUE/V+ installed.
S
Wide 3.5V to 28V DC Supply Range
S
42V Input Transient Tolerance
S
Proven PCB Layout
S
Fully Assembled and Tested
Features
Evaluates: MAX16974
Ordering Information
PART
MAX16974EVKIT+
TYPE
EV Kit
+Denotes
lead(Pb)-free and RoHS compliant.
Component List
DESIGNATION
CBST
QTY
1
DESCRIPTION
0.1µF
Q10%,
6.3V X5R ceramic
capacitor (0402)
TDK C1005X5R0J104K
5600pF
Q10%,
50V X7R ceramic
capacitor (0603)
Murata GRM188R71H562K
Not installed, 120pF
Q5%,
50V
C0G ceramic capacitor (0603)
Murata GRM1885C1H121J
100pF
Q5%,
50V C0G ceramic
capacitor (0603)
Murata GRM1885C1H101J
Not installed, ceramic capacitor
(0603)
47µF
Q20%,
50V electrolytic
capacitor (D8)
Panasonic EEE-FK1H470XP
0.1µF
Q10%,
50V X7R ceramic
capacitors (0603)
Murata GRM188R71H104K
4.7µF
Q10%,
50V X7R ceramic
capacitors (1210)
Murata GRM32ER71H475K
22µF
Q20%,
10V X7R ceramic
capacitors (1210)
Murata GRM32ER71A226K
Not installed, 1000pF
Q10%,
50V
X7R ceramic capacitor (0603)
Murata GRM188R71H102K
DESIGNATION
CVL
QTY
1
DESCRIPTION
2.2µF
Q10%,
10V X7R ceramic
capacitor (0603)
Murata GRM188R71A225K
3A, 60V Schottky diode
Diodes Inc. B360B
3-pin header
Not installed, 0I jumpers (0603)
0I
Q5%
resistors (0603)
4.7µH
Q20%,
2.8A, 20mI
inductor (7.0mm x 7.5mm)
Panasonic ETQP5M4R7YFM
Not installed, multipurpose test
point
20kI
Q1%
resistor (0603)
Not installed, resistors (0603)
12.1kI
Q1%
resistor (0603)
20kI
Q5%
resistor (0603)
10kI
Q5%
resistor (0603)
Not installed, 3I
Q5%
resistor
(0603)
High-voltage automotive step-
down converter (16 TSSOP-EP*)
Maxim MAX16974AUE/V+
Shunts
PCB: MAX16974 EVALUATION
KIT+
CCOMP1
1
D1
JU1
JU2, JU7
JU3, JU6,
RTEST
L1
1
1
0
3
CCOMP2
0
CCRES
1
1
CFB1
0
LX
RCOMP
RFB1, RFB2,
RFB3
RFOSC
RFSYNC
RRESB
RSNUB
0
1
0
1
1
1
0
CIN1
1
CIN2, CIN3
2
CIN4, CIN5
2
U1
—
—
1
1
1
COUT, COUT2
2
CSNUB
0
*EP
= Exposed pad.
/V denotes an automotive qualified part.
_______________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
MAX16974 Evaluation Kit
Evaluates: MAX16974
Component Suppliers
SUPPLIER
Diodes Incorporated
Murata Electronics North America, Inc.
Panasonic Corp.
TDK Corp.
PHONE
805-446-4800
770-436-1300
800-344-2112
847-803-6100
www.diodes.com
www.murata-northamerica.com
www.panasonic.com
www.component.tdk.com
WEBSITE
Note:
Indicate that you are using the MAX16974 when contacting these component suppliers.
Quick Start
• MAX16974 EV kit
Recommended Equipment
• 12V at 2A DC power supply
• Digital voltmeter (DVM)
• 2A DC load (2.5I,
10W)
The EV kit is fully assembled and tested. Follow the steps
below to verify board operation:
The IC synchronizes to an external clock signal applied
at FSYNC. The signal at FSYNC must have a 10% higher
frequency than the internal clock period for proper
synchronization.
External Clock Input (FSYNC)
Procedure
1) Verify that all jumpers (JU1, JU2, JU3, JU6, and JU7)
are in their default positions, as shown in Table 1.
2) Connect the DVM between the VOUT and GND pads.
3) Connect the load between the VOUT and GND pads.
4) Connect the power supply between the EXT_VBAT
and GND pads.
5) Enable the 12V power supply.
6) Verify that VOUT = 5V.
7) Verify that RESB is high.
The output voltage of the IC can be programmed
between 1V and 10V. Although the IC’s output voltage
and reset threshold can be set individually, the EV kit
supports the use of a combined resistive-divider network
to set the desired output voltage and the reset threshold
using three resistors (RFB1, RFB2, and RFB3). Use the
following formula to determine the RFB3 of the resistive-
divider network:
RFB3 =
(
RFB1+RFB2 +RFB3
)
×
V
REF
/V
OUT
where V
REF
= 1V and V
OUT
is the desired output voltage.
RFB2 =
(
(
RFB1+RFB2 +RFB3
)
×
V
REF_RES
/V
RES
)
−
RFB3
where V
REF_RES
is 1.2V (refer to the
Electrical
Characteristics
section in the MAX16974 IC data sheet)
and V
RES
is the desired reset threshold in volts.
The precision of the reset-threshold function is depen-
dent on the tolerance of the resistors used for the divider.
Refer to the MAX16974 IC data sheet for details.
Some applications require the addition of a compensa-
tion capacitor at CFB1. Contact the factory for applica-
tions assistance.
The 0I resistors at JU3 and JU6 must be moved to
locations JU2 and JU7 to enable the combined resistive-
divider network. As shipped from the factory, the 0I
resistors are installed at JU3 and JU6, so that FB is tied
to VL and RESETI is tied to ground, selecting the factory
settings.
Output-Voltage/RESET Threshold
Resistive-Divider Network
Detailed Description of Hardware
The MAX16974 EV kit provides a proven layout for the
MAX16974 IC. The EV kit is designed to fully demon-
strate the functionality of the IC as follows:
• Verify output-voltage regulation
• Verify power-good behavior and reset-threshold
selection
• Easy programmability of different output voltages
between 1V and 10V
• Startup and shutdown performance
• Current-limit performance
The following detailed descriptions enable the user to
program the EV kit per application requirements.
2
______________________________________________________________________________________
MAX16974 Evaluation Kit
Evaluates: MAX16974
The
RES
signal is asserted when RESETI is below 1.2V.
The RFB1, RFB2, and RFB3 values should be chosen to
set RESETI = 1.2V when the OUT voltage is too low. The
recommended resistor-divider bias current is 50FA.
The CRES pin of the IC is for programming the power-
good delay for the IC. The internal threshold of the CRES
comparator is 1.25V. The CRES pin sources approxi-
mately 10µA current. Placing a capacitor (CCRES) from
CRES to GND programs the delay time of the power-
good indicator.
Contact the factory for assistance in selecting compo-
nents for other output voltages.
Reset-Timeout Selection
Output-Voltage Selection
Table 1. Jumper Descriptions (JU1, JU2, JU3, JU6, JU7)
JUMPER
JU1
SIGNAL
EN
SHUNT POSITION
1-2*
2-3
0I jumper installed
Open*
JU3
FB
0I jumper installed*
Open
0I jumper installed*
Open
JU7
*Default
position.
RESETI
0I jumper installed
Open*
DESCRIPTION
EN is tied to VSUP (battery input); normal operation.
EN is tied to GND; shutdown.
Output voltage is determined by RFB1, RFB2, and RFB3. OUT regulates
FB to 1.00V at the RFB2/RFB3 junction. JU3 must be open.
JU3 should be installed. See the JU3 description.
FB is tied to BIAS; the output voltage is preset to 5V. JU2 must be open.
JU2 should be installed. See the JU2 description.
RESETI is tied to GND; the reset threshold is preset to 90% of VOUT.
JU7 must be open.
JU7 should be installed. See the JU7 description.
Reset threshold is determined by RFB1, RFB2, and RFB3. Reset occurs
when RESETI drops down to 1.2V. JU6 must be open.
JU6 should be installed. See the JU6 description.
JU2
FB
JU6
RESETI
_______________________________________________________________________________________
3
MAX16974 Evaluation Kit
Evaluates: MAX16974
Figure 1. MAX16974 EV Kit Schematic
4
______________________________________________________________________________________
MAX16974 Evaluation Kit
Evaluates: MAX16974
1.0”
1.0”
Figure 2. MAX16974 EV Kit Component Placement Guide—
Component Side
Figure 3. MAX16974 EV Kit PCB Layout—Component Side
1.0”
Figure 4. MAX16974 EV Kit PCB Layout—Ground Layer 2
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