CAT4237TD-GT3 ON Semiconductor, CAT4237TD-GT3 Datasheet - Page 8

• Manufacturer Part Number: CAT4237TD-GT3
• Description: IC LED DRVR WHT BCKLGHT TSOT23-5
• Manufacturer: ON Semiconductor
• Type: Backlight, White LEDr

Specifications of CAT4237TD-GT3

• Constant Current: Yes
• Topology: PWM, Step-Up (Boost)
• Number Of Outputs: 1
• Internal Driver: Yes
• Type - Primary: Backlight
• Type - Secondary: White LED
• Frequency: 800kHz ~ 1.3MHz
• Voltage - Supply: 2.8 V ~ 5.5 V
• Voltage - Output: 30V
• Mounting Type: Surface Mount
• Package / Case: TSOT-23-5, TSOT-5, TSOP-5
• Operating Temperature: -40°C ~ 85°C
• Current - Output / Channel: 40mA
• Internal Switch(s): Yes
• Efficiency: 87%
• Number Of Digits: 8
• Low Level Output Current: 1 mA
• High Level Output Current: 40 mA
• Operating Supply Voltage: 2.8 V to 5.5 V
• Maximum Supply Current: 1.5 mA
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: CAT4237TD-GT3TR

Application Information
External Component Selection
Capacitors
4.7 mF on the input and 0.22 mF on the output. Under normal
condition, a 4.7 mF input capacitor is sufficient. For
applications with higher output power, a larger input
capacitor of 10 mF may be appropriate. X5R and X7R
capacitor types are ideal due to their stability across
temperature range.
Inductor
CAT4237 applications. In cases where the efficiency is
critical, inductances with lower series resistance are
preferred. Inductors with current rating of 300 mA or higher
are
CDRH3D16−330 33 mH inductor has a rated current of
320 mA and a series resistance (D.C.R.) of 520 mW typical.
Schottky Diode
peak current flowing through it. The Schottky diode
performance is rated in terms of its forward voltage at a
The CAT4237 only requires small ceramic capacitors of
A 33 mH inductor is recommended for most of the
The current rating of the Schottky diode must exceed the
recommended
for
most
applications.
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given current. In order to achieve the best efficiency, this
forward voltage should be as low as possible. The response
time is also critical since the driver is operating at 1 MHz.
Central Semiconductor Schottky diode CMDSH05−4
(500 mA rated) is recommended for most applications.
LED Current Setting
connected between the feedback pin (FB) and ground. The
formula below gives the relationship between the resistor
and the current:
Table 5. RESISTOR R
The LED current is set by the external resistor R
LED Current (mA)
10
15
20
25
30
5
R
1
+
1
AND LED CURRENT
0.3 V
LED
current
R
1
60
30
20
15
12
10
(W)
1