参数资料
型号: ICL7663SCBA
厂商: Intersil
文件页数: 7/8页
文件大小: 0K
描述: IC REG LDO ADJ 40MA 8-SOIC
标准包装: 980
稳压器拓扑结构: 正,可调式
输出电压: 1.3 V ~ 16 V
输入电压: 1.5 V ~ 16 V
稳压器数量: 2
电流 - 输出: 40mA(最小)
工作温度: 0°C ~ 70°C
安装类型: 表面贴装
封装/外壳: 8-SOIC(0.154",3.90mm 宽)
供应商设备封装: 8-SOIC
包装: 管件
ICL7663S
High output currents can be obtained only as far as package
dissipation allows. It is strongly recommended that output
the regulated output voltage reaches 90% of its final value in
20ms. From:
current-limit sensing be used in such cases.
Current-Limit Sensing - The on-chip comparator (C in the
? V
I = C ,C
? t
(20 x 10 -3 )
=
I OUT 0.9V OUT
= 0.022
I OUT
V OUT
Functional Diagram) permits shutdown of the regulator
output in the event of excessive current drain. As Figure 8
shows, a current-limiting resistor, R CL , is placed in series
with V OUT2 and the SENSE terminal is connected to the
load side of R CL . When the current through R CL is high
enough to produce a voltage drop equal to V CL (0.5V) the
voltage feedback is by-passed and the regulator output will
be limited to this current. Therefore, when the maximum load
current (I LOAD ) is determined, simply divide V CL by I LOAD to
obtain the value for R CL .
In addition, where such a capacitor is used, a current-limiting
resistor is also suggested (see “Current-Limit Sensing”).
Producing Output Voltages with Negative Temperature
Coefficients -The ICL7663S has an additional output which
is 0.9V relative to GND and has a tempco of +2.5mV/°C. By
applying this voltage to the inverting input of amplifier A (i.e.,
the V SET pin), output voltages having negative TC may be
produced. The TC of the output voltage is controlled by the
R 2 /R 3 ratio (see Figure 9 and its design equations).
R 1
R 2
C L
- TC
- REF
V IN
0.047 μ F
V+ IN SENSE
V OUT2
V OUT1
V TC
V SET
20 ?
R CL
604k ?
R 2
10 μ F V OUT
+5V
+
V
R 3
V SET
+
V
V OUT
GND SHDN
210k ?
R 1
EQ. 1: V OUT = V SET
(
1+
R 2 )
R 1
+
R 2
R 3
(V SET - V TC )
R 2 + R 1
EQ. 2:
TC V OUT =
-
R 2
R 3
(TC V TC ) in mV/°C
V OUT =
I CL =
R 1
V CL
R CL
V SET = 5V
= 25mA
Where:V SET = 1.3V
V TC = 0.9V
TCV TC = +2.5mV/°C
FIGURE 9. GENERATING NEGATIVE TEMPERATURE
FIGURE 8. POSITIVE REGULATOR WITH CURRENT LIMIT
Logic-Controllable Shutdown - When equipment is not
needed continuously (e.g., in remote data-acquisition
systems), it is desirable to eliminate its drain on the system
until it is required. This usually means switches, with their
unreliable contacts. Instead, the ICL7663S can be shut
down by a logic signal, leaving only I Q (under 4 μ A) as a
drain on the power source. Since this pin must not be left
COEFFICIENTS
Applications
Boosting Output Current with External Transistor
The maximum available output current from the ICL7663S is
40mA. To obtain output currents greater than 40mA, an
external NPN transistor is used connected as shown in
Figure 10.
open, it should be tied to ground if not needed. A voltage of
less than 0.3V for the ICL7663S will keep the regulator ON,
and a voltage level of more than 1.4V but less than V+ IN will
turn the outputs OFF. If there is a possibility that the control
V+ IN V OUT1
V OUT2
100 ?
EXTERNAL PIN
POWER
TRANSISTOR
signal could exceed the regulator input (V+ IN ) the current
from this signal should be limited to 100 μ A maximum by a
high value (1M ? ) series resistor. This situation may occur
when the logic signal originates from a system powered
separately from that of the regulator.
Additional Circuit Precautions - This regulator has poor
V IN
10 μ F
SENSE
V SET
GND SHDN
0.47 ?
604k ?
V OUT
+5V
210k ?
rejection of voltage fluctuations from AC sources above
10Hz or so. To prevent the output from responding (where
this might be a problem), a reservoir capacitor across the
load is advised. The value of this capacitor is chosen so that
7
FIGURE 10. BOOSTING OUTPUT CURRENT WITH EXTERNAL
TRANSISTOR
FN3180.5
July 21, 2005
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