ON Semiconductor CAT4201 User manual

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CAT4201 LED Driver Evaluation Board Manual
INTRODUCTION
This document describes the CAT4201EVAL2
evaluation board for the CAT4201 high efficiency
step-down LED driver. Boards equipped with a 9V
battery and separate LED module can be used for
demonstrations (see Figure 1).
The CAT4201 is a high efficiency step-down LED
driver from Catalyst Semiconductor. This device is
designed to drive high brightness LEDs up to 350mA
from a power supply up to 28V. The LED brightness is
controlled by a single resistor from the RSET pin to
GND. Analog dimming and idle mode control are
available through the CTRL input. An external circuit
is provided on the CAT4201EVAL2 for PWM dimming.
OPERATION PROCEDURE
The CAT4201EVAL2 board has two modes of
operation. The first is normal operation and the second
is operation with PWM dimming. Normal operation is
set by placing jumper J1 in the right side position with
pins 2 and 3 tied together. In this mode, the CTRL pin
is pulled up to the LED cathode (LED-). The LED(s) will
be at full brightness as long as the CTRL pin is greater
than 3V. LED current can be set from 70mA to 350mA
by adjusting potentiometer R2.
To set the board for PWM dimming, jumper J1 should
be placed in the left side position with pins 1 and 2
tied together. A PWM signal can be applied to the
PWM pin to dim the LED brightness. The amplitude of
the PWM signal should be greater than 1V.
DEVICE DEMONSTRATION
To set up the CAT4201EVAL2 for demonstrations, the
board should be configured for normal operation with
a 9V battery securely placed in the holder. A separate
LED module should also be plugged into the 6-pin
connector, as shown in Figure 1. To turn on the LED,
press and hold the POWER button. The LED will turn
off once the button is released.
Figure 1. CAT4201AGEVB with LED Module
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CAT4201EVAL2
SCHEMATIC
VBAT
R4
1Ω
0.25W
C1
4.7µF
U1
VBAT
D
C2
1 F 0µ
LED+
K3
LED+
NC
LEDn+
R1
8.2kΩ
R2
47kΩ
CAT4201
RSET
CTRL SW
GND
R3
1kΩ
CTRL
L
33µH
PNP
Q1
LED-
R7
10kΩ
R8
NC
LED-
J2
LED Module
Note:
LED+ is at lower half of
PCB.
LEDn-
>1V
0V
PWM
R5
1kΩ
R6
47kΩ
1
J1
10kΩ
Q2
NPN
LED– is at upper half of
PCB
Figure 2. CAT4201AGEVB Schematic
BILL OF MATERIALS
Name Manufacturer Description Part Number Units
U1 On Semi High Efficiency Step-Down LED Driver, SOT-23-5 CAT4201 1
Q1 On Semi PNP Bipolar Transistor -45V / -500mA, SOT-23 BC807-25LT1G 1
Q2 On Semi NPN Bipolar Transistor 45V / 100mA, SOT-23 BC847CLT1G 1
DCentral Semi Schottky Diode 40V / 500mA, Size SOD-323 CMDSH05-4 1
C1 Murata Ceramic Capacitor 4.7µF/ 50V, X7R, Size 1210 GRM32ER71H475KA88L 1
C2 Taiyo Yuden Ceramic Capacitor 10µF / 35V, X5R, Size 1210 GMK325BJ106KN-T 1
LSumida Inductor 33µH, low DCR, 0.97A CDRH6D28-330 1
R1 Yageo SMT Resistor 1/10W, 8.2kΩ, 0603 9C06031A8201FKHFT 1
R2 Vishay Trim Pot. 47kΩT63YB473K 1
R3,R5 Yageo SMT Resistor 1/10W, 1kΩ, 0603 9T06031A1001FBHFT 2
R4 Panasonic SMT Resistor 1Ω/ 500mW Size 1210 ERJ-P14J1R0U 1
R6 Yageo SMT Resistor 1/10W, 47kΩ, 0603 9T06031A4702FBHFT 1
R7, R8 Yageo SMT Resistor 1/10W, 10kΩ, 0603 9T06031A1002FBHFT 2
J1 Tyco 3 Pin Header Connector 0.1" Pitch 640452-3 1
J2 Tyco 2 Pin Header Connector 0.1" Pitch 640452-2 1
K3 Tyco 6 Pin Header Receptacle 0.1" Pitch 535676-5 1
HDK SPST Pushbutton Switch (not shown in schematic) KSM0631A 1
Keystone 9V Battery Holder (optional) 1294 1
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Test Procedure for the CAT4201AGEVB Evaluation Board
Introduction
This document describes the test procedure for the CAT4201 evaluation board. The test
procedure must be followed step-by step in order to verify that the evaluation board is
fully functional.
Test set-up
The CAT4201 evaluation board must have the jumper J1 installed between pins 2 and 3
(right position).
The test set-up uses the LED module plugged into the CAT4201 evaluation board.
The LED current is measured by removing the LED module jumper J2 and connecting
an ammeter (A) between those two pins, see figure below.
VS = 12V
ISUPPLY = 100mA
+
PS
-
V V = 0.22V
ILED = 300mA
A
J2
J1
Pot R2
Legend:
ƒ (PS) = 12V DC power supply, connected between GND and VBAT
ƒ (A) = Ammeter, connected to LED module across J2 connector (jumper
removed)
ƒ (V) = Voltmeter, connected between R1/R2 midpoint and GND
Note: The LED of the LED module is very bright and should be covered for eye
protection.
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Test Procedure
The test procedure is achieved by following the sequence below step-by-step.
1. Connect the voltmeter (V) between R1/R2 midpoint and GND.
2. Connect the power supply (PS) between VBAT (+) and GND (-).
3. Turn the power supply on.
4. Measure the voltage on voltmeter (V).
5. Turn the potentiometer R2 and adjust until voltage is 0.22V.
6. Measure the LED current (A).
7. The LED current must be between: 270mA ≤ILED ≤330mA.
8. Measure the supply current on the power supply.
9. The supply current must be between: 90mA ≤ISUPPLY ≤115mA.
10. Turn off the power supply (PS).
11. Disconnect the CAT4201 evaluation board.
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