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参数资料
| 型号： | LT3956EUHE#TRPBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | SWITCHING REGULATOR, PQCC36 |
| 封装： | 5 X 6 MM, LEAD FREE, PLASTIC, QFN-36 |
| 文件页数： | 18/20页 |
| 文件大小： | 1424K |
| 代理商： | LT3956EUHE#TRPBF |
LT3956
3956f
pin FuncTions
FB: Voltage Loop Feedback Pin. FB is intended for con-
stant-voltage regulation or for LED protection/open LED
detection. The internal transconductance amplifier with
output VC will regulate FB to 1.25V (nominal) through the
DC/DC converter. If the FB input is regulating the loop, the
VMODE pull-down is asserted. This action may signal an
open LED fault. If FB is driven above the FB threshold (by
an external power supply spike, for example), the VMODE
pull-down will be de-asserted and the PWMOUT pin will
be driven low to protect the LEDs from an overcurrent
event. Do not leave the FB pin open. If not used, connect
to GND.
ISN: Connection point for the negative terminal of the
current feedback resistor. If ISN is greater than 2.9V, the
LED current can be programmed by ILED = 250mV/RLED
when VCTRL > 1.2V or ILED = (VCTRL –100mV)/(4 RLED)
if VCTRL < 1V. Input bias current is typically 20A. Below
3V, ISN is an input to the short-circuit protection feature
that forces GATE to 0V if ISP exceeds ISN by more than
350mV (typ).
ISP:Connectionpointforthepositiveterminalofthecurrent
feedback resistor. Input bias current for this pin depends
on CTRL pin voltage, as shown in the Typical Performance
Characteristics. ISP is an input to the short-circuit protec-
tion feature when ISN is less than 3V.
VC: Transconductance Error Amplifier Output Pin. This pin
is used to stabilize the voltage loop with an RC network.
This pin is high impedance when PWM is low, a feature
that stores the demand current state variable for the next
PWM high transition. Connect a capacitor between this
pin and GND; a resistor in series with the capacitor is
recommended for fast transient response.
CTRL: Current Sense Threshold Adjustment Pin. Regula-
ting threshold V(ISP – ISN) is 0.25 VCTRL plus an offset
for 0V < VCTRL < 1V. For VCTRL > 1.2V the current sense
threshold is constant at the full-scale value of 250mV. For
1V < VCTRL < 1.2V, the dependence of the current sense
threshold upon VCTRL transitions from a linear function
to a constant value, reaching 98% of full-scale value by
VCTRL = 1.1V. Connect CTRL to VREF for the 250mV default
threshold. Do not leave this pin open.
NC:NoInternalConnection.Thesepinsmaybeleftfloating
or connected to an adjacent pin.
EN/UVLO: Shutdown and Undervoltage Detect Pin. An
accurate 1.22V falling threshold with externally program-
mable hysteresis detects when power is OK to enable
switching. Rising hysteresis is generated by the external
resistor divider and an accurate internal 2.1A pull-down
current. Above the 1.24V (nominal) threshold (but below
6V), EN/UVLO input bias current is sub-A. Below the
falling threshold, a 2.1A pull-down current is enabled so
the user can define the hysteresis with the external resis-
tor selection. An undervoltage condition resets soft-start.
Tie to 0.4V, or less, to disable the device and reduce VIN
quiescent current below 1A.
INTVCC: Regulated supply for internal loads, GATE driver
and PWMOUT driver. Supplied from VIN and regulates to
7.15V (typical). INTVCC must be bypassed with a 4.7F
capacitor placed close to the pin. Connect INTVCC directly
to VIN if VIN is always less than or equal to 7V.
GND: Ground. The exposed pad, Pin 37, is ground and
must be soldered directly to the ground plane.
VIN: Input Supply Pin. Must be locally bypassed with
a 0.22F (or larger) capacitor to PGND placed close to
the IC.
SW: The exposed pad, Pin 38, is the drain of the switch-
ing N-channel MOSFET and must be connected to the
external inductor.
PGND: Source terminal of switch and the GND input to
the switch current comparator. Kelvin connect to the GND
plane close to the IC using Pin 12. Pins 13 to 17 should be
connectedexternallytothePGNDterminalsofcomponents
in the switching path. See the Board Layout section.
PWMOUT: Buffered Version of the PWM Signal. This pin is
used to drive the LED load disconnect N-channel MOSFET
or level shift. This pin also serves in a protection function
for the FB overvoltage condition—will toggle if the FB
input is greater than the FB regulation voltage (VFB) plus
60mV (typical). The PWMOUT pin is driven from INTVCC.
Use of a MOSFET with gate cut-off voltage higher than
1V is recommended.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT3956IUHE#PBF | 功能描述:IC LED DVR BUCK BOOST 36-VQFN RoHS:是 类别:集成电路 (IC) >> PMIC - LED 驱动器 系列:- 标准包装:6,000 系列:- 恒定电流:- 恒定电压:- 拓扑:开路漏极，PWM 输出数:4 内部驱动器:是 类型 - 主要:LED 闪烁器 类型 - 次要:- 频率:400kHz 电源电压:2.3 V ~ 5.5 V 输出电压:- 安装类型:表面贴装 封装/外壳:8-VFDFN 裸露焊盘 供应商设备封装:8-HVSON 包装:带卷 (TR) 工作温度:-40°C ~ 85°C 其它名称:935286881118PCA9553TK/02-TPCA9553TK/02-T-ND |
| LT3956IUHE#TRPBF | 功能描述:IC LED DVR BUCK BOOST 36-VQFN RoHS:是 类别:集成电路 (IC) >> PMIC - LED 驱动器 系列:- 标准包装:6,000 系列:- 恒定电流:- 恒定电压:- 拓扑:开路漏极，PWM 输出数:4 内部驱动器:是 类型 - 主要:LED 闪烁器 类型 - 次要:- 频率:400kHz 电源电压:2.3 V ~ 5.5 V 输出电压:- 安装类型:表面贴装 封装/外壳:8-VFDFN 裸露焊盘 供应商设备封装:8-HVSON 包装:带卷 (TR) 工作温度:-40°C ~ 85°C 其它名称:935286881118PCA9553TK/02-TPCA9553TK/02-T-ND |
| LT3956IUHE-PBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:80VIN, 80VOUT Constant-Current, Constant-Voltage Converter |
| LT3956IUHE-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:80VIN, 80VOUT Constant-Current, Constant-Voltage Converter |
| LT3957 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Wide Input Voltage Range |
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