参数资料
型号: MC34163PG
厂商: ON Semiconductor
文件页数: 9/16页
文件大小: 0K
描述: IC REG BUCK BOOST INV ADJ 16DIP
标准包装: 25
类型: 降压(降压),升压(升压),反相
输出类型: 可调式
输出数: 1
输出电压: 1.25 V ~ 40 V
输入电压: 2.5 V ~ 40 V
PWM 型: 电压模式
频率 - 开关: 50kHz
电流 - 输出: 3.4A
同步整流器:
工作温度: 0°C ~ 70°C
安装类型: 通孔
封装/外壳: 16-DIP(0.300",7.62mm)
包装: 管件
供应商设备封装: 16-DIP
产品目录页面: 1118 (CN2011-ZH PDF)
其它名称: MC34163PGOS
MC34163, MC33163
RSC +
CB(min) + I D t + 4.0 mA ton + 0.001 ton
RSC(min) +
+ 0.0735 W
The switch current is converted to a voltage by inserting
a fractional ohm resistor, R SC , in series with V CC and output
switch transistor Q 2 . The voltage drop across R SC is
monitored by the Current Sense comparator. If the voltage
drop exceeds 250 mV with respect to V CC , the comparator
will set the latch and terminate output switch conduction on
a cycle ? by ? cycle basis. This Comparator/Latch
configuration ensures that the Output Switch has only a
single on ? time during a given oscillator cycle. The
calculation for a value of R SC is:
0.25 V
Ipk (Switch)
Figures 12 and 13 show that the Current Sense comparator
threshold is tightly controlled over temperature and has a
typical input bias current of 1.0 m A. The propagation delay
from the comparator input to the Output Switch is typically
200 ns. The parasitic inductance associated with R SC and the
circuit layout should be minimized. This will prevent
unwanted voltage spikes that may falsely trip the Current
Limit comparator.
Internal thermal shutdown circuitry is provided to protect
the IC in the event that the maximum junction temperature
is exceeded. When activated, typically at 170 ° C, the Latch
is forced into the “Set” state, disabling the Output Switch.
This feature is provided to prevent catastrophic failures from
accidental device overheating. It is not intended to be used
as a replacement for proper heatsinking.
Driver and Output Switch
To aid in system design flexibility and conversion
efficiency, the driver current source and collector, and
output switch collector and emitter are pinned out
separately. This allows the designer the option of driving the
output switch into saturation with a selected force gain or
driving it near saturation when connected as a Darlington.
The output switch has a typical current gain of 70 at 2.5 A
and is designed to switch a maximum of 40 V collector to
emitter, with up to 3.4 A peak collector current. The
minimum value for R SC is:
0.25 V
3.4 A
When configured for step ? down or voltage ? inverting
applications, as in Figures 21 and 25, the inductor will
forward bias the output rectifier when the switch turns off.
Rectifiers with a high forward voltage drop or long turn ? on
delay time should not be used. If the emitter is allowed to go
additional device heating and reduced conversion
efficiency.
Figure 10 shows that by clamping the emitter to 0.5 V, the
collector current will be in the range 10 m A over
temperature. A 1N5822 or equivalent Schottky barrier
rectifier is recommended to fulfill these requirements.
A bootstrap input is provided to reduce the output switch
saturation voltage in step ? down and voltage ? inverting
converter applications. This input is connected through a
series resistor and capacitor to the switch emitter and is used
to raise the internal 2.0 mA bias current source above V CC .
An internal zener limits the bootstrap input voltage to V CC
+7.0 V. The capacitor ’s equivalent series resistance must
limit the zener current to less than 100 mA. An additional
series resistor may be required when using tantalum or other
low ESR capacitors. The equation below is used to calculate
a minimum value bootstrap capacitor based on a minimum
zener voltage and an upper limit current source.
D V 4.0 V
Parametric operation of the MC34163 is guaranteed over
a supply voltage range of 2.5 V to 40 V. When operating
below 3.0 V, the Bootstrap Input should be connected to
V CC . Figure 16 shows that functional operation down to
1.7 V at room temperature is possible.
Package
The MC34163 is contained in a heatsinkable 16 ? lead
plastic dual ? in ? line package in which the die is mounted on
a special heat tab copper alloy lead frame. This tab consists
of the four center ground pins that are specifically designed
to improve thermal conduction from the die to the circuit
board. Figures 17 and 18 show a simple and effective
method of utilizing the printed circuit board medium as a
heat dissipater by soldering these pins to an adequate area of
copper foil. This permits the use of standard layout and
mounting practices while having the ability to halve the
junction ? to ? air thermal resistance. These examples are for
a symmetrical layout on a single ? sided board with two
ounce per square foot of copper.
APPLICATIONS
The following converter applications show the simplicity
and flexibility of this circuit architecture. Three main
converter topologies are demonstrated with actual test data
shown below each of the circuit diagrams.
sufficiently negative, collector current will flow, causing
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