19-1243; Rev 1; 10/08
MAX16831 Evaluation Kit
General Description
The MAX16831 evaluation kit (EV kit) demonstrates the
MAX16831 current-mode, high-brightness LED
(HBLED) driver IC. The MAX16831 EV kit is configured
as a step-down/step-up (buck-boost) topology circuit
with peak inductor current and average LED current
control for external LEDs. The MAX16831 EV kit oper-
ates from a DC supply voltage of 9V to 40V and is con-
figured to deliver 1A of current. The maximum output
voltage of the LED string can be up to 28V.
The MAX16831 EV kit can be configured for analog-
control PWM or digital PWM dimming operation using
either an analog linear DC voltage or a digital PWM
input signal to control the LEDs’ brightness. This EV kit
has an undervoltage lockout (UVLO) feature that dis-
ables the EV kit and overvoltage protection that pro-
tects the circuit under no-load conditions. The EV kit
circuit also features a clock output and features an
input for synchronizing to an external clock. The
MAX16831 EV kit is a fully assembled and tested sur-
face-mount printed-circuit board (PCB).
Caution: Do not power up the MAX16831 EV kit
without connecting a load to the LED+ and LED-
PCB pads.
Warning: Voltages exceeding 42V may exist on the
LED+ and LED- output pads.
o
1A Output Current
o
Analog-Control PWM Dimming
o
PWM Dimming Control
o
Output Overvoltage Protection
o
Buffered Clock Output
o
Lead-Free and RoHS Compliant
o
Fully Assembled and Tested
Features
o
9V to 40V Wide Supply Voltage Range
Evaluates: MAX16831
Ordering Information
PART
MAX16831EVKIT+
TYPE
EV Kit
+Denotes
lead-free and RoHS-compliant.
Component List
DESIGNATION QTY
C1, C3, C4,
C5, C15
5
DESCRIPTION
0.1µF ±10%, 50V X7R ceramic
capacitors (0603)
Murata GRM188R71H104K
1µF ±10%, 16V X7R ceramic
capacitor (0603)
Murata GRM188R71C105K
1000pF ±10%, 50V X7R ceramic
capacitors (0603)
Murata GRM188R71H102K
10µF ±10%, 16V X7R ceramic
capacitor (1206)
Murata GRM31CR71C106K
100µF ±20%, 50V electrolytic
capacitor (10.3mm x 10.3mm)
Panasonic EEVFCIH101P
10µF ±10%, 50V X7S ceramic
capacitor (1210)
Taiyo Yuden UMK325C7106KM
4.7µF ±10%, 100V X7R ceramic
capacitors (2220)
Murata GRM55DR61H106K
DESIGNATION QTY
C13
1
DESCRIPTION
0.047µF ±10%, 50V X7R ceramic
capacitor (0603)
TDK C1608X7R1H473K
100pF ±5%, 50V C0G ceramic
capacitors (0603)
Murata GQM1885C1H101J
300mA, 100V diode (SOD123)
Diodes Inc. 1N4148W-7-F
Not installed, diode (SOD123)
3A, 100V Schottky diode (PowerDI)
Diodes Inc. PDS3100
1A, 100V Schottky diode (SMA)
Diodes Inc. B1100-13-F
2-pin header
Not installed, inductor
10µH, 9.2A inductor
Sumida CDEP147NP-100MC-95
60V, 3.2A n-channel MOSFET (6-pin TSOP)
Vishay Si3458DV-E3
C2
1
C16, C17
2
C6, C14
2
D1
D2
D3
D4
JU1
L1
L2
N1
1
0
1
1
1
0
1
1
C7
1
C8
1
C9
1
C10, C11, C12
3
________________________________________________________________
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.
MAX16831 Evaluation Kit
Evaluates: MAX16831
Component List (continued)
DESIGNATION QTY
N2
N3
R1
R2
R3
R4
R5
R6, R7
1
0
1
1
1
1
1
2
DESCRIPTION
100V, 42A n-channel MOSFET (D-Pak)
International Rectifier IRLR3110Z
Not installed, MOSFET (D-Pak)
73.2kΩ ±1% resistor (0603)
12.4kΩ ±1% resistor (0603)
0.1Ω ±1%, 500mW sense resistor
(1206)
IRC/TT LRC-LR-1206LF-01-R100-F
100Ω ±5% resistor (0603)
1Ω ±5% resistor (0603)
0.04Ω ±1%, 2W sense resistors (2512)
IRC/TT LRC-LR-2512LF-01-R040-F
—
—
1
1
DESIGNATION QTY
R8
R9
R10, R15
R11
R12
R13
R14
U1
0
1
2
1
1
1
1
1
DESCRIPTION
Not installed, resistor (0805)
280kΩ ±1% resistor (0603)
4.99kΩ ±1% resistors (0603)
1kΩ ±1% resistor (0603)
3.32kΩ ±1% resistor (0603)
42.2kΩ ±1% resistor (0603)
100kΩ potentiometer (single turn)
Current-mode HBLED driver
(32 TQFN-EP*)
Maxim MAX16831ATJ+
Shunt (JU1)
PCB: MAX16831 Evaluation Kit+
*EP
= Exposed pad.
Component Suppliers
SUPPLIER
Diodes, Inc.
International Rectifier
IRC, Inc.
Murata Electronics North America, Inc.
Panasonic Corp.
Sumida Corp.
TDK Corp.
Vishay
PHONE
805-446-4800
310-322-3331
361-992-7900
770-436-1300
800-344-2112
847-545-6700
847-803-6100
402-563-6866
www.irf.com
www.irctt.com
www.murata-northamerica.com
www.panasonic.com
www.sumida.com
www.component.tdk.com
www.vishay.com
WEBSITE
www.diodes.com
Note:
Indicate that you are using the MAX16831 when contacting these component suppliers.
Quick Start
Recommended Equipment
Before beginning, the following equipment is needed:
• 9V to 40V, 4A power supply
• Two digital voltmeters
• A series-connected LED string rated at 1A (28V max)
• A current probe to measure LED current
Warning: Voltages exceeding 42V may exist on the
LED+ and LED- output pads.
1) Verify that a shunt is installed across jumper JU1
(analog dimming control).
2) Connect the power supply’s positive terminal to the
V
IN
PCB pad on the EV kit. Connect the power sup-
ply’s ground terminal to PGND PCB pad.
3) Connect the digital voltmeters across the V
IN
and
PGND PCB pads and the LED+ and LED-
PCB pads.
4) Connect the anode of the LED string to the
LED+ pad.
5) Connect the cathode of the LED string to the
LED- pad.
Procedures
The MAX16831 EV kit is fully assembled and tested.
Follow the steps below to verify board operation.
Caution: Do not turn on the power supply until all
connections are completed and do not power up the
MAX16831 EV kit without connecting a load to the
LED+ and LED- PCB pads.
2
_______________________________________________________________________________________
MAX16831 Evaluation Kit
6) Clip the current probe across the LED+ wire to mea-
sure the LED current.
7) Turn on the power supply and increase the input
voltage to 9V.
8) Adjust potentiometer R14 to obtain the desired LED
current duty cycle.
9) Measure the voltage between the LED+ and LED-
PCB pads.
Setting External LED Current
Resistor R3 sets the MAX16831 EV kit average LED
current to 1A. Use the following equation to calculate
R3 when reconfiguring the LED current:
R3
=
107mV
I
LED
Evaluates: MAX16831
where I
LED
is the LED current.
Detailed Description
The MAX16831 evaluation kit (EV kit) demonstrates the
MAX16831 current-mode HBLED driver IC. The
MAX16831 EV kit is configured in a step-down/step-up
(buck-boost) topology with peak current control and
average current control for a string of user-supplied
external HBLEDs. The MAX16831 EV kit operates from a
DC supply voltage of 9V to 40V and requires up to 4A.
The circuit is configured to deliver 1A of current into
series LED string with a maximum 28V forward voltage.
The EV kit sets the maximum series inductor current to
8.3A using parallel resistors R6 and R7. The average
LED current is set to 1A using resistor R3. A CLKOUT
PCB pad is available to monitor the oscillator frequen-
cy. A DIM PCB pad is also provided for PWM dimming
operation of the external LEDs and to monitor the ana-
log DC voltage applied at the MAX16831 IC DIM pin.
LED Dimming Control
LED dimming can be achieved on the MAX16831 EV kit
by applying a digital PWM signal or an analog DC volt-
age at the DIM PCB input pad. Jumper JU1, poten-
tiometer R14, resistor R15, and capacitor C15 configure
the MAX16831 EV kit for analog-control PWM dimming
operation.
Place a shunt across jumper JU1 to set the EV kit for
analog-control PWM dimming and adjust potentiometer
R14. The analog DC voltage at the DIM PCB pad sets
the duty cycle of the LED current, which controls the
external LED brightness. The MAX16831 IC DIM pin
voltage can be monitored by placing a voltmeter across
the DIM and AGND PCB pads.
Use the following equation to calculate the voltage at
the DIM PCB pad, which is necessary to program the
LED output current duty cycle, D:
DIM
≅
(D
×
2.6V)
+
0.2V
where DIM is the analog DC voltage at the MAX16831
EV kit DIM PCB pad in volts, and D is the duty cycle of
the LED output current.
When operating the MAX16831 EV kit with analog-con-
trol PWM dimming, the LED dimming frequency is inter-
nally set by the MAX16831 IC to 200Hz.
Remove the shunt at jumper JU1 to control LED dim-
ming using a digital PWM signal at the DIM PCB pad.
Apply a digital PWM signal with a 3.2V to 15V logic-high
level in the 80Hz to 2kHz frequency range and adjust
the duty cycle to adjust the LED brightness. See Table
1 for jumper JU1 setting for LED dimming operation.
Undervoltage Lockout (UVLO)
The MAX16831 EV kit’s UVLO threshold is configured to
8.3V using resistors R1 and R2. The UVEN PCB pad
can be used to disable the EV kit circuit by connecting
UVEN to AGND. To configure the circuit to a different
UVLO threshold, refer to the
Setting the UVLO
Threshold
section in the MAX16831 IC data sheet.
Peak Inductor Current-Limit Setting
The parallel combination of current-sense resistors R6
and R7 sets the EV kit’s peak inductor current limit to
8.3A. Use the following equation to calculate the total
resistance needed to reconfigure the inductor peak
current limit:
R
TOTAL
=
160mV
I
PEAK
where I
PEAK
is the inductor peak current and R
TOTAL
is
the total parallel resistance placed at the R6 and R7
PCB pads.
Refer to
the ILIM and HICCUP Comparator
section in
the MAX16831 IC data sheet for additional information
on setting the peak current-limit threshold.
Table 1. MAX16831 LED Dimming
Operation (Jumper JU1)
SHUNT POSITION
Not installed
Installed
EV KIT DIMMING OPERATION
PWM signal applied at DIM PCB pad
Analog DC voltage adjusted using R14
_______________________________________________________________________________________
3
MAX16831 Evaluation Kit
Evaluates: MAX16831
CLK OUTPUT
The MAX16831 EV kit features a buffered digital clock
output, CLKOUT. The MAX16831 PWM clock frequen-
cy is programmed to 300kHz by resistor R13. To syn-
chronize the MAX16831 EV kit to an external clock
signal, connect a clock signal with a 2.8V to 5.5V
logic level and 125kHz to 500kHz square wave at the
RTSYNC PCB pad. Refer to the
Oscillator, Clock, and
Synchronization
section in the MAX16831 IC data
sheet for information on setting the MAX16831 IC
PWM frequency.
Output Overvoltage Protection
The maximum voltage on the LED+ PCB pad is limited
to 70.8V, with respect to GND, by a feedback network
formed by resistors R9 and R10. When the voltage at
LED+ exceeds the programmed 70.8V threshold,
PWM switching is terminated and no further energy is
transferred to the load connected between LED+ and
LED-. Refer to the
Setting the Overvoltage Threshold
section in the MAX16831 IC data sheet for setting the
overvoltage threshold.
If the EV kit is turned on with no load, the voltage at
LED+ may rise to unsafe levels. Even though the EV
kit has overvoltage protection, connect the speci-
fied load before powering up the EV kit.
4
_______________________________________________________________________________________
VIN
VIN
PGND
C4
0.1μF
C5
0.1μF
VIN
26
CS+
LO
N.C.
DGT
QGND
SNS
AGND
U1
SNS+
SNS+_IN
C6
1000pF
DRI
REG2
C8
100μF
50V
4
DRV_N3
1
2
3
N3
OPEN
1
3
SNS+_IN
2
2
R6
0.04Ω
1%
D2
OPEN
R7
0.04Ω
1%
D3
1
DRV_N3
R8
OPEN
R11
1kΩ
1%
C13
0.047μF
C16
100pF
R10
4.99kΩ
1%
R9
280kΩ
1%
C10
4.7μF
100V
C11
4.7μF
100V
C12
4.7μF
100V
3
D4
1
2
C9
10μF
50V
6
DIM
4
N2
RTSYNC
DRV
1
D1
CLKOUT
I.C.
I.C.
I.C.
COMP
CS
FB
OV
SGND
SGND
18
7
8
19
VIN
L2
10μH
L1
SHORT
REF
20
21
56
LED-
12
R4
100Ω
22
N1
23
3
4
24
25
I.C.
HI
REG2
R1
73.2kΩ
UVEN
1%
N.C.
UVEN
REG1
2
3
C2
1μF
4
CLMP
1
V
CC
CS-
Figure 1. MAX16831 EV Kit Schematic
C3
0.1μF
REG2
LED+
R3
0.1Ω
1%
32
31
30
29
28
27
5
R2
AGND 12.4kΩ
1%
C1
0.1μF
R14
100kΩ 3
1
R15
4.99kΩ
1%
AGND
MAX16831
2
C17
100pF
DIM
C15
0.1μF
C7
10μF
16V
R5
1Ω
JU1
RTSYNC
R13
42.2kΩ
1%
9 10 11
1
12
14
15
16 17
CLKOUT
13
R12
3.32kΩ
1%
LED+
LED+
C14
1000pF
Evaluates: MAX16831
_______________________________________________________________________________________
AGND PGND
MAX16831 Evaluation Kit
5
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