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参数资料
| 型号： | AMC78L05DMF |
| 厂商： | Electronic Theatre Controls, Inc. |
| 英文描述： | 100mA / 3-TERMINAL 5V REGULATOR |
| 中文描述： | 百毫安/三端5V稳压器 |
| 文件页数： | 20/28页 |
| 文件大小： | 468K |
| 代理商： | AMC78L05DMF |
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AMC7820
SBAS231B
www.ti.com
20
inverting input of TEC integrator, OPA7. The noninverting
input of OPA7 connects to the thermostat DAC(DAC0),
which sets the desired temperature of the pump laser diode
module. The temperature that a certain voltage represents
depends upon the value of the thermistor used and the drive
current provided to that thermistor.
Pin 1 (SW2_OUT) controls the external TEC Power Current
Driver (DRV591, a PWM power driver) which can be re-
placed with a linear driver (OPA5xx) if configured properly. In
the application of Figure 7, 2.5V on pin 1 sets the TEC
current to zero.
In normal operation, SW2 is enabled and OPA7 connects to
the DRV591. The voltage across the thermistor controls the
TEC current. When SW2 is disabled, the DRV591 is con-
nected to SW3, which connects to 2.5V in the bipolar mode
(which is the default mode). This results in zero TEC current,
and shuts down the TEC. Meanwhile, TEC SOFT_START
CONTROLLER drives the output of OPA7 to become equal
to the reference voltage of 2.5V. This action provides a soft
start when SW2 is enabled.
The TEC current is sensed across an external sense resistor
(0.1
) by the amplifier OPA6, and is fed to analog channel
7 of the ADC. OPA6 is connected as a difference amplifier
and is offset (by 2.5V) to provide the measurement of the
bidirectional TEC current. The host processor monitors the
current and takes proper action when necessary.
TEC CONTROL LOOP COMPENSATION
The AMC7820 has a dedicated amplifier (OPA7) to control
the temperature of a Laser Diode Module. The amplifier can
be configured in several ways to implement the control loop
function, but it is commonly configured as a PID (Propor-
tional-Integral-Derivative) controller. In this mode, the control
loop consists of a low-frequency pole, a zero that cancels this
pole below the dominant pole frequency of the TEC and, at
higher frequencies, linear gain that promotes fast settling of
the TEC.
Usually, the component values of the control loop are se-
lected based upon the characteristics of the TEC (thermal
gain and time constant), the gain of the TEC power driver,
and the desired loop response. Frequently, the characteris-
tics of the TEC are not known, which can lead to difficulty in
designing the compensator analytically. An empirical design
procedure using the actual loop components (TEC, power
driver, and AMC7820) can be used to determine the com-
pensator component values.
With this method, the loop response is monitored while
making step changes to the control loop. A step change can
be provided by writing data values to DAC0. An oscilloscope
is used to monitor the temperature of the thermistor at the
T_Sensor _Voltage pin.
The suggested manual tuning procedure is based upon the
components shown in Figure 8.
1) Establish the setpoint of the control loop at the lowest
anticipated temperature setting of the laser module. At this
operating point, the gain of the temperature control loop is at
it
’
s highest. The loop is best compensated at this point.
2) Initially select R
1
= 2M, C
1
= 1uF, C
2
= 2uF. To improve
the response, decrease the value of C
2
. This increases the
gain of the compensator near the dominant pole frequency
of the TEC, resulting in faster settling times of the loop.
However, at some value of C
2
the loop will start to oscillate.
At this point, fix C
2
at 3x to 4x this value.
3) Verify the settling behavior of the control loop at the
highest anticipated laser module setpoint temperature. The
loop response may be somewhat different at this operating
point. A compromise value of C
2
may be needed to balance
the loop response at these operating point extremes.
Typical values of the loop compensation components are:
R
1
= 2M, C
1
= 1uF, C
2
= 0.1uF. See Figures 9 through 12
for typical loop responses.
FIGURE 8. Compensation Loop.
OPA9
OPA7
100
μ
A
C
1
R
1
Monitor
Pin 2
Ref Out
+2.5V
2.5V Ref
61.9k
61.9k
143.3k
OPA548
143.3k
R
T
10k
TEC+
TEC
–
C
2
DAC0
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| AMC78L05LPF | 100mA / 3-TERMINAL 5V REGULATOR |
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相关代理商/技术参数 |
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|---|---|
| AMC78L05LP | 制造商:ADDTEK 制造商全称:ADDTEK 功能描述:100mA / 3-TERMINAL 5V REGULATOR |
| AMC78L05LPF | 制造商:ADDTEK 制造商全称:ADDTEK 功能描述:100mA / 3-TERMINAL 5V REGULATOR |
| AMC78L05PK | 制造商:ADDTEK 制造商全称:ADDTEK 功能描述:100mA / 3-TERMINAL 5V REGULATOR |
| AMC78L05PKF | 制造商:ADDTEK 制造商全称:ADDTEK 功能描述:100mA / 3-TERMINAL 5V REGULATOR |
| AMC78N-V00 | 制造商:Panasonic Industrial Company 功能描述:HOLDER |
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