- 您现在的位置：买卖IC网 > PDF目录17146 > LM3423MHBKBSTEV/NOPB (National Semiconductor)BOARD EVAL BUCK BOOST LM3423 PDF资料下载
参数资料
| 型号： | LM3423MHBKBSTEV/NOPB |
| 厂商： | National Semiconductor |
| 文件页数： | 20/67页 |
| 文件大小： | 0K |
| 描述： | BOARD EVAL BUCK BOOST LM3423 |
| 标准包装： | 1 |
| 系列： | PowerWise® |
| 电流 - 输出 / 通道： | 1A |
| 输出及类型： | 1，非隔离 |
| 输出电压： | 35V |
| 特点： | 可调光 |
| 输入电压： | 4.5 ~ 35 V |
| 已供物品： | 板 |
| 已用 IC / 零件： | LM3423 |
| 其它名称： | LM3423MHBKBSTEV |
第1页第2页第3页第4页第5页第6页第7页第8页第9页第10页第11页第12页第13页第14页第15页第16页第17页第18页第19页当前第20页第21页第22页第23页第24页第25页第26页第27页第28页第29页第30页第31页第32页第33页第34页第35页第36页第37页第38页第39页第40页第41页第42页第43页第44页第45页第46页第47页第48页第49页第50页第51页第52页第53页第54页第55页第56页第57页第58页第59页第60页第61页第62页第63页第64页第65页第66页第67页
V TURN - OFF = 1 . 24V x ¨ ¨
R OV 1
SNVS574E – JULY 2008 – REVISED MAY 2013
Floating
?
§ 0 . 5 x R OV1 + R OV2 ·
?
? 1
(27)
In the ground referenced configuration, the voltage across R OV2 is V O - 1.24V whereas in the floating
configuration it is V O - 620 mV where 620 mV approximates V BE of the PNP.
The over-voltage hysteresis (V HYSO ) is defined:
V HYSO = 23 P A x R OV 2
(28)
LED+
R OV2
LM3421/23
LED-
OVP
R OV1
Figure 27. Floating Output OVP Circuitry
The OVLO feature can cause some interesting results if the OVLO trip-point is set too cose to V O . At turn-on, the
converter has a modest amount of voltage overshoot before the control loop gains control of I LED . If the overshoot
exceeds the OVLO threshold, the controller shuts down, opening the dimming MosFET. This isolates the LED
load from the converter and the output capacitance. The voltage will then discharge very slowly through the HSP
and HSN pins until V O drops below the lower threshold, where the process repeats. This looks like the LEDs are
blinking at around 2 Hz. This mode can be escaped if the input voltage is reduced.
INPUT UNDER-VOLTAGE LOCKOUT (UVLO)
The nDIM pin is a dual-function input that features an accurate 1.24V threshold with programmable hysteresis as
shown in Figure 28 . This pin functions as both the PWM dimming input for the LEDs and as a V IN UVLO. When
the pin voltage rises and exceeds the 1.24V threshold, 23 μA (typical) of current is driven out of the nDIM pin into
the resistor divider providing programmable hysteresis.
V IN
LM3421/23
23 P A
R UV2
R UV1
R UVH
(optional)
nDIM
1.24V
UVLO
Figure 28. UVLO Circuit
When using the nDIM pin for UVLO and PWM dimming concurrently, the UVLO circuit can have an extra series
resistor to set the hysteresis. This allows the standard resistor divider to have smaller resistor values minimizing
PWM delays due to a pull-down MosFET at the nDIM pin (see PWM DIMMING section). In general, at least 3V
of hysteresis is preferable when PWM dimming, if operating near the UVLO threshold.
The turn-on threshold (V TURN-ON ) is defined as follows:
20
Copyright ? 2008–2013, Texas Instruments Incorporated
Product Folder Links: LM3421 LM3421-Q1 LM3423 LM3423-Q1
相关PDF资料 |
PDF描述 |
|---|---|
| EEM06DRST-S288 | CONN EDGECARD 12POS .156 EXTEND |
| HPL1005-13N | INDUCTOR 13NH 2% 0402 SMD |
| MC33342DR2G | IC CTRLR BATTERY FAST CHRG 8SOIC |
| 18R683C | INDUCTOR RADIAL 68UH 1.35A |
| EEV-FC1C470P | CAP ALUM 47UF 16V 20% SMD |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LM3423MHBSTEVAL | 制造商:Texas Instruments 功能描述:N-Channel Controllers For Constant Current LED Drivers Evaluation Board |
| LM3423MHBSTEVAL/NOPB | 功能描述:BOARD EVAL BOOST FOR LM3423 RoHS:是 类别:编程器，开发系统 >> 评估板 - LED 驱动器 系列:PowerWise® 标准包装:1 系列:PowerWise® 电流 - 输出 / 通道:20mA 输出及类型:1，非隔离 输出电压:17V 特点:可调光 输入电压:2.7 ~ 5.5 V 已供物品:板 已用 IC / 零件:LM3508 相关产品:LM3508TLX-ND - IC LED DRVR WHT BCKLGT 9USMDLM3508TLDKR-ND - IC LED DRVR WHT BCKLGT 9MICROSMDLM3508TLCT-ND - IC LED DRVR WHT BCKLGT 9MICROSMDLM3508TLTR-ND - IC LED DRVR WHT BCKLGT 9MICROSMD |
| LM3423MHX | 制造商:Rochester Electronics LLC 功能描述: 制造商:Texas Instruments 功能描述: |
| LM3423MHX/NOPB | 功能描述:LED照明驱动器 RoHS:否 制造商:STMicroelectronics 输入电压:11.5 V to 23 V 工作频率: 最大电源电流:1.7 mA 输出电流: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:SO-16N |
| LM3423Q0 | 制造商:NSC 制造商全称:National Semiconductor 功能描述:N-Channel Controllers for Constant Current LED Drivers |
发布紧急采购，3分钟左右您将得到回复。