19-1243; Rev 1; 10/08
MAX16831 Evaluation Kit
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 operates from a DC supply voltage of 9V to 40V and is configured 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 analogcontrol 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 disables the EV kit and overvoltage protection that protects 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 surface-mount printed-circuit board (PCB).
Caution: Do not power up the MAX16831 EV kit
without connecting a load to the LED+ and LEDPCB pads.
Features
o 9V to 40V Wide Supply Voltage Range
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
Ordering Information
PART
TYPE
MAX16831EVKIT+
EV Kit
+Denotes lead-free and RoHS-compliant.
Warning: Voltages exceeding 42V may exist on the
LED+ and LED- output pads.
Component List
DESIGNATION QTY
DESCRIPTION
C1, C3, C4,
C5, C15
5
0.1µF ±10%, 50V X7R ceramic
capacitors (0603)
Murata GRM188R71H104K
C2
1
1µF ±10%, 16V X7R ceramic
capacitor (0603)
Murata GRM188R71C105K
C6, C14
2
1000pF ±10%, 50V X7R ceramic
capacitors (0603)
Murata GRM188R71H102K
1
10µF ±10%, 16V X7R ceramic
capacitor (1206)
Murata GRM31CR71C106K
1
100µF ±20%, 50V electrolytic
capacitor (10.3mm x 10.3mm)
Panasonic EEVFCIH101P
1
10µF ±10%, 50V X7S ceramic
capacitor (1210)
Taiyo Yuden UMK325C7106KM
C7
C8
C9
C10, C11, C12
3
4.7µF ±10%, 100V X7R ceramic
capacitors (2220)
Murata GRM55DR61H106K
DESIGNATION QTY
DESCRIPTION
C13
1
0.047µF ±10%, 50V X7R ceramic
capacitor (0603)
TDK C1608X7R1H473K
C16, C17
2
100pF ±5%, 50V C0G ceramic
capacitors (0603)
Murata GQM1885C1H101J
D1
1
300mA, 100V diode (SOD123)
Diodes Inc. 1N4148W-7-F
D2
0
Not installed, diode (SOD123)
D3
1
3A, 100V Schottky diode (PowerDI)
Diodes Inc. PDS3100
D4
1
1A, 100V Schottky diode (SMA)
Diodes Inc. B1100-13-F
JU1
1
2-pin header
L1
0
Not installed, inductor
L2
1
10µH, 9.2A inductor
Sumida CDEP147NP-100MC-95
N1
1
60V, 3.2A n-channel MOSFET (6-pin TSOP)
Vishay Si3458DV-E3
________________________________________________________________ Maxim Integrated Products
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.
1
Evaluates: MAX16831
General Description
Evaluates: MAX16831
MAX16831 Evaluation Kit
Component List (continued)
DESIGNATION QTY
DESCRIPTION
DESIGNATION QTY
DESCRIPTION
R8
0
Not installed, resistor (0805)
R9
1
280kΩ ±1% resistor (0603)
N2
1
100V, 42A n-channel MOSFET (D-Pak)
International Rectifier IRLR3110Z
N3
0
Not installed, MOSFET (D-Pak)
R10, R15
2
4.99kΩ ±1% resistors (0603)
R1
1
73.2kΩ ±1% resistor (0603)
R11
1
1kΩ ±1% resistor (0603)
R2
1
12.4kΩ ±1% resistor (0603)
R12
1
3.32kΩ ±1% resistor (0603)
1
42.2kΩ ±1% resistor (0603)
1
0.1Ω ±1%, 500mW sense resistor
(1206)
IRC/TT LRC-LR-1206LF-01-R100-F
R13
R3
R14
1
100kΩ potentiometer (single turn)
R4
1
100Ω ±5% resistor (0603)
U1
1
R5
1
1Ω ±5% resistor (0603)
Current-mode HBLED driver
(32 TQFN-EP*)
Maxim MAX16831ATJ+
2
0.04Ω ±1%, 2W sense resistors (2512)
IRC/TT LRC-LR-2512LF-01-R040-F
—
1
Shunt (JU1)
—
1
PCB: MAX16831 Evaluation Kit+
R6, R7
*EP = Exposed pad.
Component Suppliers
SUPPLIER
PHONE
WEBSITE
Diodes, Inc.
805-446-4800
International Rectifier
310-322-3331
www.diodes.com
www.irf.com
IRC, Inc.
361-992-7900
www.irctt.com
Murata Electronics North America, Inc.
770-436-1300
www.murata-northamerica.com
Panasonic Corp.
800-344-2112
www.panasonic.com
Sumida Corp.
847-545-6700
www.sumida.com
TDK Corp.
847-803-6100
www.component.tdk.com
Vishay
402-563-6866
www.vishay.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
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
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
VIN PCB pad on the EV kit. Connect the power supply’s ground terminal to PGND PCB pad.
3) Connect the digital voltmeters across the VIN and
PGND PCB pads and the LED+ and LEDPCB 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.
_______________________________________________________________________________________
MAX16831 Evaluation Kit
7) Turn on the power supply and increase the input
voltage to 9V.
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:
8) Adjust potentiometer R14 to obtain the desired LED
current duty cycle.
9) Measure the voltage between the LED+ and LEDPCB pads.
R3 =
where ILED 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 frequency. A DIM PCB pad is also provided for PWM dimming
operation of the external LEDs and to monitor the analog 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 voltage at the DIM PCB input pad. Jumper JU1, potentiometer 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:
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
IPEAK
where IPEAK is the inductor peak current and RTOTAL 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.
107mV
ILED
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-control PWM dimming, the LED dimming frequency is internally set by the MAX16831 IC to 200Hz.
Remove the shunt at jumper JU1 to control LED dimming 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.
Table 1. MAX16831 LED Dimming
Operation (Jumper JU1)
SHUNT POSITION
EV KIT DIMMING OPERATION
Not installed
PWM signal applied at DIM PCB pad
Installed
Analog DC voltage adjusted using R14
_______________________________________________________________________________________
3
Evaluates: MAX16831
6) Clip the current probe across the LED+ wire to measure the LED current.
Evaluates: MAX16831
MAX16831 Evaluation Kit
CLK OUTPUT
Output Overvoltage Protection
The MAX16831 EV kit features a buffered digital clock
output, CLKOUT. The MAX16831 PWM clock frequency is programmed to 300kHz by resistor R13. To synchronize 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.
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.
4
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 specified load before powering up the EV kit.
_______________________________________________________________________________________
CLKOUT
RTSYNC
DIM
AGND
C15
0.1μF
C2
1μF
AGND PGND
C17
100pF
R15
4.99kΩ
1%
C1
0.1μF
R13
42.2kΩ
1%
JU1
2
R14
100kΩ 3
1
R2
AGND 12.4kΩ
1%
8
7
6
5
4
3
2
CLKOUT
RTSYNC
DIM
REF
AGND
REG1
UVEN
N.C.
9 10 11
COMP
12
REG2
30
29
U1
28
C14
1000pF
13
R12
3.32kΩ
1%
27
C5
0.1μF
14
C13
0.047μF
R11
1kΩ
1%
MAX16831
HI
31
C4
0.1μF
CLMP
32
VCC
I.C.
1
I.C.
R1
73.2kΩ
UVEN
1%
I.C.
I.C.
CSFB
LED+
R3
0.1Ω
1%
26
15
OV
REG2
25
VIN
R10
4.99kΩ
1%
DGT
N.C.
DRV
DRI
SNS+
SNS
QGND
16 17
CS+
C3
0.1μF
SGND
PGND
CS
LO
SGND
VIN
18
19
20
21
22
23
24
3
R8
OPEN
D2
OPEN
D1
C16
100pF
1
1
C7
10μF
16V
R5
1Ω
C6
1000pF
2
2
12
R4
100Ω
N1
56
R9
280kΩ
1%
1
N2
REG2
4
3
4
DRV_N3
R6
0.04Ω
1%
DRV_N3
SNS+_IN
LED-
3
R7
0.04Ω
1%
1
4
N3
OPEN
L2
10μH
1
C10
4.7μF
100V
D3
2
SNS+_IN
3
C8
100μF
50V
L1
SHORT
C11
4.7μF
100V
C9
10μF
50V
1
2
C12
4.7μF
100V
D4
VIN
LED+
LED+
Evaluates: MAX16831
VIN
MAX16831 Evaluation Kit
Figure 1. MAX16831 EV Kit Schematic
_______________________________________________________________________________________
5
Evaluates: MAX16831
MAX16831 Evaluation Kit
Figure 2. MAX16831 EV Kit Component Placement Guide—Components Side
Figure 3. MAX16831 EV Kit PCB Layout—Component Side
6
_______________________________________________________________________________________
MAX16831 Evaluation Kit
Evaluates: MAX16831
Figure 4. MAX16831 EV Kit PCB Layout—GND Layer 2
Figure 5. MAX16831 EV Kit PCB Layout—VCC Layer 3
_______________________________________________________________________________________
7
Evaluates: MAX16831
MAX16831 Evaluation Kit
Figure 6. MAX16831 EV Kit PCB Layout—Solder Side
8
_______________________________________________________________________________________
MAX16831 Evaluation Kit
REVISION
NUMBER
REVISION
DATE
0
11/07
Initial Release
—
1
10/08
Component C9 part number change.
1
DESCRIPTION
PAGES
CHANGED
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________ 9
© 2008 Maxim Integrated Products
is a registered trademark of Maxim Integrated Products, Inc.
Evaluates: MAX16831
Revision History