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参数资料
| 型号： | TNY377P |
| 厂商： | POWER INTEGRATIONS INC |
| 元件分类： | 稳压器 |
| 英文描述： | 1.4 A SWITCHING REGULATOR, 280 kHz SWITCHING FREQ-MAX, PDIP7 |
| 封装： | PLASTIC, MS-001AB, DIP-8/7 |
| 文件页数： | 15/20页 |
| 文件大小： | 1076K |
| 代理商： | TNY377P |
Rev. A 05/07
TNY375-380
www.powerint.com
BYPASS/MULTI-FUNCTION Pin Undervoltage
The BYPASS/MULTI-FUNCTION pin undervoltage circuitry
disables the power MOSFET when the BYPASS/MULTI-
FUNCTION pin voltage drops below 4.9 V in steady state
operation. Once the BYPASS/MULTI-FUNCTION pin voltage
drops below 4.9 V in steady state operation, it must rise back to
5.85 V to enable (turn-on) the power MOSFET.
Over Temperature Protection
The thermal shutdown circuitry senses the die temperature.
The threshold is typically set at 142 °C with 75 °C hysteresis.
When the die temperature rises above this threshold, the power
MOSFET is disabled and remains disabled, until the die
temperature falls by 75 °C, at which point it is re-enabled. A
large hysteresis of 75 °C (typical) is provided to prevent
overheating of the PC board due to a continuous fault condition.
Current Limit
The current limit circuit senses the current in the power
MOSFET. When this current exceeds the internal threshold
(I
LIMIT), the power MOSFET is turned off for the remainder of that
cycle. The current limit state machine reduces the current limit
threshold by discrete amounts under medium and light loads.
The leading edge blanking circuit inhibits the current limit
comparator for a short time (t
LEB) after the power MOSFET is
turned on. This leading edge blanking time has been set so
that current spikes caused by typical capacitance and
secondary-side rectifier reverse recovery time will not cause
premature termination of the switching pulse.
Auto-Restart
In the event of a fault condition such as output overload, output
short circuit, or an open loop condition, TinySwitch-PK enters
into auto-restart operation. An internal counter clocked by the
oscillator is reset every time the EN/UV pin is pulled low. If the
EN/UV pin is not pulled low for 8192 switching cycles
(or 32 ms), the power MOSFET switching is normally disabled
for 1 second (except in the case of line undervoltage condition,
in which case it is disabled until the condition is removed). The
auto-restart alternately enables and disables the switching of
the power MOSFET until the fault condition is removed.
Figure 5 illustrates auto-restart circuit operation in the presence
of an output short circuit.
In the event of a line undervoltage condition, the switching of
the power MOSFET is disabled beyond its normal 1 second
until the line undervoltage condition ends.
Adaptive Switching Cycle On-Time Extension
Adaptive switching cycle on-time extension keeps the cycle on
until current limit is reached, instead of prematurely terminating
after the DC
MAX signal goes low. This feature reduces the
minimum input voltage required to maintain regulation, typically
extending hold-up time and minimizing the size of bulk
capacitor required. The on-time extension is disabled during
the startup of the power supply, and after auto-restart, until the
power supply output reaches regulation.
Line Undervoltage Sense Circuit
The DC line voltage can be monitored by connecting an
external resistor from the DC line to the EN/UV pin. During
power-up or when the switching of the power MOSFET is
disabled in auto-restart, the current into the EN/UV pin must
exceed 25
mA to initiate switching of the power MOSFET.
During power-up, this is accomplished by holding the BYPASS/
MULTI-FUNCTION pin to 4.9 V while the line undervoltage
condition exists. The BYPASS/MULTI-FUNCTION pin then rises
from 4.9 V to 5.85 V when the line undervoltage condition goes
away. Once MOSFET switching is enabled, the DC line voltage
is ignored unless the power supply enters auto-restart mode in
the event of a fault condition. When the switching of the power
MOSFET is disabled in auto-restart mode and a line under-
voltage condition exists, the auto-restart counter is stopped.
This stretches the disable time beyond its normal 1 second until
the line undervoltage condition ends.
The line undervoltage circuit also detects when there is no
external resistor connected to the EN/UV pin (less than ~1
mA
into the pin). In this case the line undervoltage function is
disabled.
TinySwitch-PK Operation
TinySwitch-PK devices operate in the current limit mode.
When enabled, the oscillator turns the power MOSFET on at the
beginning of each cycle. The MOSFET is turned off when the
current ramps up to the current limit or when the DC
MAX limit is
reached (applicable when On-Time Extension is disabled).
Since the highest current limit level and frequency of a
TinySwitch-PK design are constant, the power delivered to the
load is proportional to the primary inductance of the transformer
and peak primary current squared. Hence, designing the
supply involves calculating the primary inductance of the
transformer for the maximum output power required. If the
TinySwitch-PK is appropriately chosen for the power level, the
current in the calculated inductance will ramp up to current limit
before the DC
MAX limit is reached.
PI-4320-030106
0
1000
2000
Time (ms)
0
5
0
10
100
200
300
V
DRAIN
V
DC-OUTPUT
Figure 5.
Auto-Restart Operation.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| TNY377PN | 功能描述:交流/直流开关转换器 23W 85-265 VAC 28 W 230 VAC RoHS:否 制造商:STMicroelectronics 输出电压:800 V 输入/电源电压（最大值）:23.5 V 输入/电源电压（最小值）:11.5 V 开关频率:115 kHz 电源电流:1.6 mA 工作温度范围:- 40 C to + 150 C 安装风格:SMD/SMT 封装 / 箱体:SSO-10 封装:Reel |
| TNY378G | 制造商:POWERINT 制造商全称:Power Integrations, Inc. 功能描述:Energy-Efficient, Off-Line Switcher With Enhanced Peak Power Performance |
| TNY378GN | 功能描述:交流/直流开关转换器 27 W (85-265 VAC) 34 W (230 VAC) RoHS:否 制造商:STMicroelectronics 输出电压:800 V 输入/电源电压（最大值）:23.5 V 输入/电源电压（最小值）:11.5 V 开关频率:115 kHz 电源电流:1.6 mA 工作温度范围:- 40 C to + 150 C 安装风格:SMD/SMT 封装 / 箱体:SSO-10 封装:Reel |
| TNY378GN-TL | 功能描述:交流/直流开关转换器 27 W (85-265 VAC) 34 W (230 VAC) RoHS:否 制造商:STMicroelectronics 输出电压:800 V 输入/电源电压（最大值）:23.5 V 输入/电源电压（最小值）:11.5 V 开关频率:115 kHz 电源电流:1.6 mA 工作温度范围:- 40 C to + 150 C 安装风格:SMD/SMT 封装 / 箱体:SSO-10 封装:Reel |
| TNY378P | 制造商:POWERINT 制造商全称:Power Integrations, Inc. 功能描述:Energy-Efficient, Off-Line Switcher With Enhanced Peak Power Performance |
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