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GM19371 の電気的特性と機能

GM19371のメーカーはGammaです、この部品の機能は「BOOST WHITE LED DRIVER」です。


製品の詳細 ( Datasheet PDF )

部品番号 GM19371
部品説明 BOOST WHITE LED DRIVER
メーカ Gamma
ロゴ Gamma ロゴ 




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GM19371 Datasheet, GM19371 PDF,ピン配置, 機能
GM19371
BOOST WHITE LED DRIVER
WITH OVP
Description
The GM19371 is a step up DC/DC convert
specifically designed to drive white LED;s with a
constant current. The device can drive up to 27
LEDs from a 5V supply.
Additional feature includes output voltage limiting
when LEDs are disconnected.
GM19371 is available in SOT-26 package.
Features
‹ Inherently matched LED current
‹ Drives up to 126LEDs (9S14P) from a
12V supply
‹ 36V rugged bipolar switch
‹ Fast 1.2MHz switching frequency
‹ Over Voltage Protection, 30V
Application
Cellular phones
PDAs, Handheld Computers
Digital Cameras
Typical Application Circuits
MP3 Player
GPS Receivers
MR16 Lighting
VIN
6V to 18V
DIM
10µH
D1
C1
4.7µF
61
VIN SW
OVP 5
GM19371
4 CTRL
GND
2
FB 3
14 Strings in Parallel
9 LED in Series
RSET 20mA x 14
Figure 1 GM19371 typical application
C2
4.7µF
www.gammamicro.com.tw 1
Free Datasheet http://www.datasheet4u.com/

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GM19371 pdf, ピン配列
GM19371
BOOST WHITE LED DRIVER
WITH OVP
Absolute Maximum Ratings (Note 1)
PARAMETER
SYMBOL
RATINGS
Input Voltage
VIN 20
SW Voltage
VSW
36
FB Voltage
VFB 10
/SHDN Voltage
VCTRL
10
Junction Temperature
TJ -40 to 125
Storage Temperature
Tstg - 65 to 150
Lead Temperature (soldering, 5 sec)
260
.Note 1: Stresses greater than those listed under Maximum Ratings may cause permanent damage to the device.
Recommended Operating Conditions
Rating
Maximum Supply Voltage
Output Voltage
Operating Temperature Range
Symbol
VIN
VOUT
TOPR
Value
2.5 to 18
28
0 to 70
UNITS
V
V
V
V
°C
°C
°C
Unit
V
V
°C
Electrical Characteristics (VIN = 5V, V/SHDN = 5V, TA = 25˚C, unless otherwise noted)
Parameter
Operating Voltage Range
Feedback Voltage
FB Pin Bias Current
Supply Current
Standby Current
Switching Frequency
Maximum Duty Cycle
Switch Current Limit
Switch VCESAT
Switch Leakage Current
CTRL Voltage High
CTRL Voltage Low
CTRL Pin Bias Current
OVP Threshold
Symbol
VIN
VFB
IFB
ICC
ISTBY
fOSC
DMAX
ICL
VSAT
ILEAK
VTH
VTL
ICTRL
Condition
ILOAD = 180mA
VIN = VOUT + 1V to 16V
V/SHDN = 0V
ISW = 250mA
VSW = 5V
Min Typ Max Unit
2.5 18 V
80 95 107 mV
10 45 100 nA
2.1 3.0 mA
0.1 1.0 μA
1.1 1.3 1.6 MHz
85 90
%
650 mA
350 mV
0.01 5 μA
1.5 V
0.4 V
65 μA
29 V
3


3Pages


GM19371 電子部品, 半導体
GM19371
BOOST WHITE LED DRIVER
WITH OVP
Application Information
General Operation
The GM19371 uses a constant frequency, current mode control scheme to provide excellent line and load
regulations. See Fig 2 for GM19371operation. At the start of each oscillator cycle, the RS latch is set,
which turns on the power switch Q1. A voltage proportional to the switch current is added to a stabilizing
ramp and the resulting sum is fed into the positive terminal of the PWM comparator A2. When this voltage
exceeds the level at the negative input of A2, the RS latch is reset turning off the power switch. The level
at the negative input of A2 is set by the error amplifier A1, and is simply an amplified version of the
difference between the feedback voltage and the reference voltage of 95mV. In this manner, the error
amplifier sets the correct peak current level to keep the output in regulation. If the error amplifier’s output
increases, more current is delivered to the output; if it decreases, less current is delivered.
Over Voltage Protection and Open Circuit Protection
In case of output open circuit, while the LED strings are disconnected from the circuit or the LEDs fail
open, the feedback voltage, VFB, will be zero. The GM19371 will then switch at a high duty cycle
resulting in a high output voltage, which may cause the SW pin voltage to exceed its maximum voltage
rating. In order to prevent this condition occur, the GM19317 builds a latch-mode open-circuit protection
circuit. Based on the result from the sensing pin, OVP pin, the chip can detect the output open condition
when the OVP voltage is higher than 30V. The chip will shutdown until VIN reset
Inductor Selection
A 10uH inductor is recommended for most GM19371 applications. Although small size and high efficiency
are major concerns, the inductor should have low core losses at 1.2MHz and low DCR (copper wire
resistance).
Capacitor Selection
The small size of ceramic capacitors makes them ideal for GM19371 applications. X5R and X7R types
are recommended because they retain their capacitance over wider voltage and temperature ranges than
other types such as Y5V or Z5U. A 4.7uF input capacitor and a 4.7uF output capacitor are sufficient for
most GM19371 applications.
Diode Selection
Schottky diodes, with their low forward voltage drop and fast reverse recovery, are the ideal choices for
GM19371 applications. The forward voltage drop of a Schottky diode represents the conduction losses in
the diode while the diode capacitance (CT or CD) represents the switching losses. For diode selection,
both forward voltage drop and diode capacitance need to be considered. Schottky diodes with higher
current ratings usually have lower forward voltage drop and larger diode capacitance, which can cause
significant switching losses at the 1.2MHz switching frequency of the GM19371. A Schottky diode rated at
1000mA is sufficient for most GM19371 applications.
Soft Start and Current Limit
The internal soft start circuit minimizes the inrush current during turning on GM19371. The Typical switch
current is limited to about 650mA by the chip.
6

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共有リンク

Link :


部品番号部品説明メーカ
GM1937

WHITE LED STEP-UP CONVERTER

Gamma
Gamma
GM19371

BOOST WHITE LED DRIVER

Gamma
Gamma


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