参数资料
型号: LT3957EUHE#PBF
厂商: Linear Technology
文件页数: 7/28页
文件大小: 0K
描述: IC REG MULTI CONFIG ADJ 36VQFN
特色产品: LT?3957/LT?3958 Converters
标准包装: 61
类型: 升压(升压),反相,回扫,Sepic
输出类型: 可调式
输出数: 1
输出电压: 1.6 V ~ 40 V
输入电压: 3 V ~ 40 V
PWM 型: 电流模式
频率 - 开关: 100kHz ~ 1MHz
电流 - 输出: 5A
同步整流器:
工作温度: -40°C ~ 125°C
安装类型: 表面贴装
封装/外壳: 36-WFQFN 裸露焊盘
包装: 管件
供应商设备封装: 36-QFN-EP(6x5)
LT3957
PIN FUNCTIONS
NC (Pins 1, 2, 10, 35, 36): No Internal Connection. Leave
these pins open or connect them to the adjacent pins.
SENSE2 (Pin 3): The Current Sense Input for the Control
Loop. Connect this pin to SENSE1 pin directly or through
a low pass ?lter (connect this pin to SENSE1 pin through
a resistor, and to SGND through a capacitor).
SGND (Pins 4, 23, 24, Exposed Pad Pin 37): Signal
Ground. All small-signal components should connect to
this ground. SGND is connected to GND inside the IC to
ensure Kelvin connection for the internal switch current
sensing. Do not connect SGND and GND externally.
SENSE1 (Pin 6): The Current Sense Output of the Inter-
nal N-channel MOSFET. Connect this pin to SENSE2 pin
directly or through a low pass ?lter (connect this pin to
SENSE1 pin through a resistor, then connect SENSE2 to
SGND through a capacitor).
SW (Pins 8, 9, 20, 21, Exposed Pad Pin 38): Drain of
Internal Power N-channel MOSFET.
GND (Pins 12, 13, 14, 15, 16, 17): Ground. These pins
connect to the source terminal of internal power N-channel
MOSFET through an internal sense resistor. GND is con-
nected to SGND inside the IC to ensure Kelvin connection
for the internal switch current sensing. Do not connect
GND and SGND externally.
EN/UVLO (Pin 25): Shutdown and Undervoltage Detect
Pin. An accurate 1.22V (nominal) falling threshold with
externally programmable hysteresis detects when power
is okay to enable switching. Rising hysteresis is generated
by the external resistor divider and an accurate internal
2μA pull-down current. An undervoltage condition resets
soft-start. Tie to 0.4V, or less, to disable the device and
reduce V IN quiescent current below 1μA.
V IN (Pin 27): Input Supply Pin. The V IN pin can be locally
bypassed with a capacitor to GND (not SGND).
INTV CC (Pin 28): Regulated Supply for Internal Loads
and Gate Driver. Supplied from V IN and regulated to
5.2V (typical). INTV CC must be bypassed to SGND with a
minimum of 4.7μF capacitor placed close to pin. INTV CC
can be connected directly to V IN , if V IN is less than 8V.
INTV CC can also be connected to a power supply whose
voltage is higher than 5.5V, and lower than V IN , provided
that supply does not exceed 8V.
VC (Pin 30): Error Ampli?er Compensation Pin. Used to
stabilize the voltage loop with an external RC network.
Place compensation components between the VC pin
and SGND.
FBX (Pin 31): Positive and Negative Feedback Pin. Re-
ceives the feedback voltage from the external resistor
divider between the output and SGND. Also modulates the
switching frequency during start-up and fault conditions
when FBX is close to SGND.
SS (Pin 32): Soft-Start Pin. This pin modulates compen-
sation pin voltage (VC) clamp. The soft-start interval is
set with an external capacitor between SS pin and SGND.
The pin has a 10μA (typical) pull-up current source to
an internal 2.5V rail. The soft-start pin is reset to SGND
by an undervoltage condition at EN/UVLO, an INTV CC
undervoltage or overvoltage condition or an internal
thermal lockout.
RT (Pin 33): Switching Frequency Adjustment Pin. Set
the frequency using a resistor to SGND. Do not leave this
pin open.
SYNC (Pin 34): Frequency Synchronization Pin. Used to
synchronize the switching frequency to an outside clock.
If this feature is used, an R T resistor should be chosen
to program a switching frequency 20% slower than the
SYNC pulse frequency. Tie the SYNC pin to SGND if this
feature is not used. SYNC is bypassed when FBX is close
to SGND.
3957f
7
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LT3957EUHETRPBF 制造商:LINER 制造商全称:Linear Technology 功能描述:Boost, Flyback, SEPIC and Inverting Converter with 5A, 40V Switch
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