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參數(shù)資料
| 型號： | HV9931 |
| 廠商： | Supertex, Inc. |
| 元件分類： | 基準電壓源/電流源 |
| 英文描述： | UNITY POWER FACTOR LED LAMP DRIVER |
| 中文描述： | 單位功率因數(shù)LED燈驅(qū)動器 |
| 文件頁數(shù)： | 5/7頁 |
| 文件大?。?/td> | 516K |
| 代理商： | HV9931 |
5
NR081505
HV9931
Functional Description
Power Topology
The HV9931 is optimized to drive Supertex’s proprietary single-
stage, single-switch, non-isolated topology, cascading an input
power factor correction (PFC) buck-boost stage and an output
buck converter power stage. This power converter topology offers
numerous advantages useful for driving high-brightness light
emitting diodes (HB LED). These advantages include unity power
factor, low harmonic distortion of the input AC line current, and low
output current ripple. The output load is decoupled from the input
voltage with a capacitor making the driver inherently failure-safe for
the output load. The power converter topology also permits reducing
the size of a filter capacitor needed, enabling use of non-electrolytic
capacitors. The latter advantage greatly improves reliability of the
overall solution.
The HV9931 is a peak current-mode controller that is specifically
designed to drive a constant current buckboost-buck power
converter. This patent pending control scheme features two identical
current sense comparators for detecting negative current signal
levels. One of the comparators regulates the output LED current.
The other one is used for sensing the input inductor current. The
second comparator is mainly responsible for the converter start-
up. The control scheme inherently features low inrush current
and input under-voltage protection. The HV9931 can operate with
programmable constant frequency or constant off-time. In many
cases, the constant off-time operating mode is preferred, since
it improves line regulation of the output current, reduces voltage
stress of the power components and simplifies regulatory EMI
compliance. (See Application Note AN-H52.)
Input Voltage Regulator
The HV9931 can be powered directly from its V
pin and takes a
voltage from 8V to 450V. When a voltage is applied at the V
pin,
the HV9931 seeks to maintain a constant 7.5V at the V
pin. The
V
voltage can be also used as a reference for the current sense
comparators. The regulator is equipped with an under-voltage
protection circuit which shuts off the HV9931 when the voltage at
the V
DD
pin falls below 6.2V.
The V
pin must be bypassed by a low ESR capacitor (≥ 0.1μF) to
provide a low impedance path for the high frequency current of the
output gate driver.
The HV9931 can also be operated by supplying a voltage at the V
pin greater than the internally regulated voltage. This will turn off
the internal linear regulator and the HV9931 will function by drawing
power from the external voltage source connected to the V
DD
pin.
PWM Dimming and Wall Dimmer Compatibility
PWM Dimming can be achieved by applying a TTL-compatible
square wave signal at the PWMD pin. When the PWMD pin is
pulled high, the gate driver is enabled and the circuit operates
normally. When the PWMD pin is left open or connected to GND,
the gate driver is disabled and the external MOSFET turns off. The
HV9931 is designed so that the signal at the PWMD pin inhibits the
driver only, and the IC need not go through the entire start-up cycle
each time ensuring a quick response time for the output current.
The power topology requires little filter capacitance at the output,
since the output current of the buck stage is continuous, and since
AC line filtering is accomplished through the middle capacitor rather
than the output one. Therefore, disabling the HV9931 via its PWMD
or V
pins can interrupt the output LED current in accordance with
the phase-controlled voltage waveform of a standard wall dimmer.
Oscillator
Connecting an external resistor from RT pin to GND programs
switching frequency:
]
[
]
T
R
K
22
+
Connecting the resistor from RT pin to GATE programs constant
off-time:
[ ]
OFF
T
s
25
Input and Output Current Feedback
Two current sense comparators are included in the HV9931. Both
comparators have their non-inverting inputs internally connected to
ground (GND). The CS1 and CS2 inputs are inverting inputs of the
comparators. Connecting a resistor divider into either of these inputs
from a positive reference voltage and a negative current sense
signal programs the current sense threshold of the comparator. The
V
voltage of the HV9931 can be used as the reference voltage.
(If more accuracy is needed, an external reference voltage can be
applied.) When either the CS
or the CS
pin voltage falls below
GND, the GATE pulse is terminated. A leading edge blanking delay
of 215ns (typ) is added. The GATE voltage becomes high again
upon receiving the next clock pulse of the oscillator circuit.
Referring to the Functional Circuit Diagram, the CS2 comparator is
responsible for regulating output current. The output LED current
can be programmed using the following equation:
1
Io
I
2
R
R
R
75V
where I
is the peak-to-peak current ripple in L2. The CS1
comparator limits the current in the input inductor L1. There is
no charge in the capacitor C1 upon the start-up of the converter.
Therefore, L2 cannot develop the output current, and the HV9931
starts-up in the input current limiting mode. The CS1 current
threshold must be programmed such that no input current limiting
occurs in normal steady-state operation. The CS1 threshold can be
programmed in accordance with a similar equation:
I
R
R
R
75V
where I
L1(PK)
is the maximum peak current in L1.
MOSFET Gate Driver
Typically, the gate driving capability of the HV9931 is limited by the
amount of power dissipation in its linear regulator. Thus, care must
be taken selecting a switching MOSFET to be used in the circuit.
An optimal trade-off must be found between the gate charge and
the on-resistance of the MOSFET to minimize the input regulator
current.
25000
F kHz
=
[
]
T
R
K
22
μ
+
=
L2
CS2
REF2
S2
+
=
)
L1 PK
CS1
REF1
S1
=
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| HV9931_07 | 制造商:SUPERTEX 制造商全稱:SUPERTEX 功能描述:HV9931 Unity Power Factor LED Lamp Driver |
| HV9931DB1 | 功能描述:電源管理IC開發(fā)工具 LED DRIVER DEMOBOARD RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類型:Battery Management 工具用于評估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V |
| HV9931DB2 | 功能描述:LED 照明開發(fā)工具 LED DRIVER DEMOBOARD RoHS:否 制造商:Fairchild Semiconductor 產(chǎn)品:Evaluation Kits 用于:FL7732 核心: 電源電壓:120V 系列: 封裝: |
| HV9931DB4 | 制造商:Supertex Inc 功能描述: |
| HV9931DB5 | 功能描述:電源管理IC開發(fā)工具 DOUBLE-BUCK LED DEMOBOARD RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類型:Battery Management 工具用于評估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V |
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