参数资料
型号: LM3421Q1MHX/NOPB
厂商: National Semiconductor
文件页数: 10/67页
文件大小: 0K
描述: IC LED DRVR HP CONS CURR 16TSSOP
标准包装: 2,500
系列: PowerWise®
恒定电流:
拓扑: PWM,SEPIC,降压(降压),升压(升压)
输出数: 1
内部驱动器:
类型 - 主要: 车载
类型 - 次要: 高亮度 LED(HBLED)
频率: 2MHz
电源电压: 4.5 V ~ 75 V
输出电压: 3 V ~ 72 V
安装类型: 表面贴装
封装/外壳: 16-TSSOP(0.173",4.40mm)裸露焊盘
供应商设备封装: 16-TSSOP-EP
包装: 带卷 (TR)
工作温度: -40°C ~ 125°C
其它名称: LM3421Q1MHX

SNVS574E – JULY 2008 – REVISED MAY 2013
V IN
BLOCK DIAGRAM
EN
6.9V LDO
Regulator
V CC
820k
V IN UVLO
HYSTERESIS
UVLO
(4.1V)
V CC UVLO
REFERENCE
Standby
1.235V
500k
nDIM
1.24V
23 P A
TLIM Thermal
Limit
Dimming
V CC
DPOL
DDRV
OVLO
LatchOff
V IN /25
Start new on time
Reset
Dominant
PGND
V CC
RCT
LEB
W = 150 ns
S
R
Q
GATE
PGND
COMP
RPD
1.235V
PWM
23 P A
OVP
HYSTERESIS
EN
CSH
HSP
HSN
IS
LEB
800 mV
0.245V
1.0V
LOGIC
CURRENT
LIMIT
LED CURRENT LOW
OVLO
11.5 P A
1.24V
OVP
LRDY
LED CURRENT HIGH
LatchOff
TIMR
FLT
AGND
1.6V
Grey pins are available in the LM3423 only.
In the LM3421, TIMR is internally shorted to AGND.
TLIM
V CC UVLO
1.24V
THEORY OF OPERATION
The LM3421/23 are N-channel MosFET (NFET) controllers for buck, boost and buck-boost current regulators
which are ideal for driving LED loads. The controller has wide input voltage range allowing for regulation of a
variety of LED loads. The high-side differential current sense, with low adjustable threshold voltage, provides an
excellent method for regulating output current while maintaining high system efficiency. The LM3421/23 uses a
Predictive Off-time (PRO) control architecture that allows the regulator to be operated using minimal external
control loop compensation, while providing an inherent cycle-by-cycle current limit. The adjustable current sense
threshold provides the capability to amplitude (analog) dim the LED current and the output enable/disable
10
Copyright ? 2008–2013, Texas Instruments Incorporated
Product Folder Links: LM3421 LM3421-Q1 LM3423 LM3423-Q1
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