TI UC1823A

UC1823A, UC2823A, UC2823B,
UC3823A, UC3823B, UC1825A,
UC2825A, UC2825B, UC3825A, UC3825B
www.ti.com
SLUS334E − AUGUST 1995 − REVISED SEPTEMBER 2010
HIGH-SPEED PWM CONTROLLER
FEATURES
D Improved Versions of the UC3823/UC3825
D
D
D
D
DESCRIPTION
The UC3823A and UC3823B and the UC3825A and
UC3825B family of PWM controllers are improved
versions of the standard UC3823 and UC3825 family.
Performance enhancements have been made to several
of the circuit blocks. Error amplifier gain bandwidth product
is 12 MHz, while input offset voltage is 2 mV. Current limit
threshold is assured to a tolerance of 5%. Oscillator
discharge current is specified at 10 mA for accurate dead
time control. Frequency accuracy is improved to 6%.
Startup supply current, typically 100 μA, is ideal for off-line
applications. The output drivers are redesigned to actively
sink current during UVLO at no expense to the startup
current specification. In addition each output is capable of
2-A peak currents during transitions.
PWMs
Compatible with Voltage-Mode or
Current-Mode Control Methods
Practical Operation at Switching Frequencies
to 1 MHz
50-ns Propagation Delay to Output
High-Current Dual Totem Pole Outputs
(2-A Peak)
Trimmed Oscillator Discharge Current
D
D Low 100-μA Startup Current
D Pulse-by-Pulse Current Limiting Comparator
D Latched Overcurrent Comparator With Full
Cycle Restart
BLOCK DIAGRAM
CLK/LEB 4
13 VC
(60%)
RT 5
CT 6
R
RAMP 7
EAOUT 3
NI
11 OUTA
*
OSC
T
SD
PWM
LATCH
1.25 V
PWM COMPARATOR
14 OUTB
12 PGND
2
E/A
9 mA
INV 1
SOFT−START COMPLETE
SS 8
CURRENT
LIMIT
1.0 V
OVER CURRENT
ILIM 9
1.2 V
RESTART
DELAY
0.2 V
VCC 15
GND 10
RESTART
DELAY
LATCH
5V
”B” 16V/10V
”A” 9.2V/8.4V
SD
S
R
R
250 mA
FAULT LATCH
UVLO
VREF
5.1 V
ON/OFF
* On the UC1823A version, toggles Q and Q are always low.
4V
VREF GOOD
INTERNAL
BIAS
16 5.1 VREF
UDG−02091
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments
semiconductor products and disclaimers thereto appears at the end of this data sheet.
PRODUCTION DATA information is current as of publication date. Products
conform to specifications per the terms of Texas Instruments standard warranty.
Production processing does not necessarily include testing of all parameters.
Copyright © 2004 −2008, Texas Instruments Incorporated
UC1823A, UC2823A, UC2823B,
UC3823A, UC3823B, UC1825A,
UC2825A, UC2825B, UC3825A, UC3825B
www.ti.com
SLUS334E − AUGUST 1995 − REVISED SEPTEMBER 2010
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during
storage or handling to prevent electrostatic damage to the MOS gates.
DESCRIPTION (CONTINUED)
Functional improvements have also been implemented in this family. The UC3825 shutdown comparator is now a
high-speed overcurrent comparator with a threshold of 1.2 V. The overcurrent comparator sets a latch that ensures full
discharge of the soft-start capacitor before allowing a restart. While the fault latch is set, the outputs are in the low state.
In the event of continuous faults, the soft-start capacitor is fully charged before discharge to insure that the fault frequency
does not exceed the designed soft start period. The UC3825 CLOCK pin has become CLK/LEB. This pin combines the
functions of clock output and leading edge blanking adjustment and has been buffered for easier interfacing.
The UC3825A and UC3825B have dual alternating outputs and the same pin configuration of the UC3825. The UC3823A
and UC3823B outputs operate in phase with duty cycles from zero to less than 100%. The pin configuration of the UC3823A
and UC3823B is the same as the UC3823 except pin 11 is now an output pin instead of the reference pin to the current
limit comparator. “A” version parts have UVLO thresholds identical to the original UC3823 and UC3825. The “B” versions
have UVLO thresholds of 16 V and 10 V, intended for ease of use in off-line applications.
Consult the application note, The UC3823A,B and UC3825A,B Enhanced Generation of PWM Controllers, (SLUA125) for
detailed technical and applications information.
ORDERING INFORMATION
UVLO
MAXIMUM
DUTY CYCLE
TA
−40°C
40°C to 85°C
−0°C
0°C to 70°C
(1)
9.2 V / 8.4 V
16 V / 10 V
SOIC−16(1)
(DW)
PDIP−16
(N)
PLCC−20(1)
(Q)
SOIC−16
(DW)
PDIP−16
(N)
PLCC−20(1)
(Q)
< 100%
UC2823ADW
UC2823AN
UC2823AQ
UC2823BDW
UC2823BN
−
< 50%
UC2825ADW
UC2825AN
UC2825AQ
UC2825BDW
UC2825BN
−
< 100%
UC3823ADW
UC3823AN
UC3823AQ
UC3823BDW
UC3823BN
−
< 50%
UC3825ADW
UC3825AN
UC3825AQ
UC3825BDW
UC3825BN
UC3825BQ
The DW and Q packages are also available taped and reeled. Add TR suffix to the device type (i.e., UC2823ADWR). To order quantities of 1000
devices per reel for the Q package and 2000 devices per reel for the DW package.
UVLO
9.2 V / 8.4 V
MAXIMUM
DUTY CYCLE
TA
−55°C
55°C to 125°C
CDIP−16
(J)
LCCC−20
(L)
< 100%
UC1823AJ, UC1823AJ883B, UC1823AJQMLV
UC1823AL, UC1823AL883B
< 50%
UC1825AJ, UC1825AJ883B, UC1825AJQMLV
UC1825AL, UC1825AL883B, UC1825ALQMLV
PIN ASSIGNMENTS
Q OR L PACKAGES
(TOP VIEW)
1
16
2
15
3
14
4
13
5
12
6
11
7
10
8
9
VREF
VCC
OUTB
VC
PGND
OUTA
GND
ILIM
EAOUT
CLK/LEB
NC
RT
CT
4
3 2 1 20 19
18
5
6
17
16
7
8
15
14
9 10 11 12 13
RAMP
SS
NC
ILIM
GND
INV
NI
EAOUT
CLK/LEB
RT
CT
RAMP
SS
NI
INV
NC
VREF
VCC
DW, J, OR N PACKAGES
(TOP VIEW)
NC = no connection
2
OUTB
VC
NC
PGND
OUTA
UC1823A, UC2823A, UC2823B,
UC3823A, UC3823B, UC1825A,
UC2825A, UC2825B, UC3825A, UC3825B
www.ti.com
SLUS334E − AUGUST 1995 − REVISED SEPTEMBER 2010
TERMINAL FUNCTIONS
NAME
CLK/LEB
TERMINAL
NO.
J or DW
Q or L
4
5
I/O
DESCRIPTION
O
Output of the internal oscillator
Timing capacitor connection pin for oscillator frequency programming. The timing capacitor should
be connected to the device ground using minimal trace length.
Output of the error amplifier for compensation
Analog ground return pin
Input to the current limit comparator
Inverting input to the error amplifier
Non-inverting input to the error amplifier
High current totem pole output A of the on-chip drive stage.
High current totem pole output B of the on-chip drive stage.
Ground return pin for the output driver stage
Non-inverting input to the PWM comparator with 1.25-V internal input offset. In voltage mode
operation, this serves as the input voltage feed-forward function by using the CT ramp. In peak
current mode operation, this serves as the slope compensation input.
Timing resistor connection pin for oscillator frequency programming
Soft-start input pin which also doubles as the maximum duty cycle clamp.
Power supply pin for the output stage. This pin should be bypassed with a 0.1-μF monolithic ceramic
low ESL capacitor with minimal trace lengths.
CT
6
8
I
EAOUT
GND
ILIM
INV
NI
OUTA
OUTB
PGND
3
10
9
1
2
11
14
12
4
13
12
2
3
14
18
15
O
−
I
I
I
O
O
−
RAMP
7
9
I
RT
SS
5
8
7
10
I
I
VC
13
17
−
VCC
15
19
−
Power supply pin for the device. This pin should be bypassed with a 0.1-μF monolithic ceramic low
ESL capacitor with minimal trace lengths
VREF
16
20
O
5.1-V reference. For stability, the reference should be bypassed with a 0.1-μF monolithic ceramic
low ESL capacitor and minimal trace length to the ground plane.
ABSOLUTE MAXIMUM RATINGS
over operating free-air temperature range unless otherwise noted(1)
UNIT
VIN
Supply voltage,
VC, VCC
22 V
IO
Source or sink current, DC
OUTA, OUTB
0.5 A
IO
Source or sink current, pulse (0.5 μs)
OUTA, OUTB
2.2 A
INV, NI, RAMP
−0.3 V to 7 V
ILIM, SS
−0.3 V to 6 V
Analog inputs
Power ground
PGND
±0.2 V
Outputs
OUTA, OUTB limits
ICLK
Clock output current
CLK/LEB
IO(EA)
Error amplifier output current
EAOUT
5 mA
ISS
Soft-start sink current
SS
20 mA
IOSC
Oscillator charging current
RT
−5 mA
TJ
Operating virtual junction temperature range
−55°C to 150°C
Tstg
Storage temperature
−65°C to 150°C
Lead temperature 1,6 mm (1/16 inch) from case for 10 seconds
tSTG
Storage temperature
Lead temperature 1,6 mm (1/16 inch) from cases for 10 seconds
(1)
PGND −0.3 V to VC +0.3 V
−5 mA
−55C°C to 150°C
−65°C to 150°C
300°C
Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, and
functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not
implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
3
UC1823A, UC2823A, UC2823B,
UC3823A, UC3823B, UC1825A,
UC2825A, UC2825B, UC3825A, UC3825B
www.ti.com
SLUS334E − AUGUST 1995 − REVISED SEPTEMBER 2010
ELECTRICAL CHARACTERISTICS
TA = −55°C to 125°C for the UC1823A/UC1825A, TA = −40°C to 85°C for the UC2823x/UC2825x, TA = 0°C to 70°C for the UC3823x/UC3825x,
RT = 3.65 kΩ, CT = 1 nF, VCC = 12 V, TA = TJ (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
5.05
5.1
5.15
V
REFERENCE, VREF
VO
Ouput voltage range
TJ = 25°C,
Line regulation
12 V ≤ VCC ≤ 20 V
2
15
Load regulation
1 mA ≤ IO ≤ 10 mA
5
20
Total output variation
Line, load, temperature
Temperature stability(1)
T(min) < TA < T(max)
0.2
Output noise voltage(1)
10 Hz < f < 10 kHz
50
Long term
stability(1)
Short circuit current
IO = 1 mA
TJ = 125°C,
5.03
1000 hours
mV
5.17
V
0.4
mV/°C
μVRMS
5
25
mV
30
60
90
mA
TJ = 25°C
375
400
425
kHz
RT = 6.6 kΩ, CT = 220 pF, TA = 25°C
0.9
1
1.1
MHz
VREF = 0 V
OSCILLATOR
fOSC
Initial accuracy(1)
Total variation(1)
Voltage stability
Temperature
stability(1)
Line, temperature
350
450
kHz
RT = 6.6 kΩ, CT = 220 pF,
0.85
1.15
MHz
12 V < VCC < 20 V
T(min) < TA < T(max)
High-level output voltage, clock
1%
+/−
5%
3.7
4
Low-level output voltage, clock
IOSC
0
0.2
Ramp peak
2.6
2.8
3
Ramp valley
0.7
1
1.25
Ramp valley-to-peak
1.6
1.8
2
9
10
11
mA
mV
Oscillator discharge current
RT = OPEN,
VCT = 2 V
V
ERROR AMPLIFIER
Input offset voltage
2
10
Input bias current
0.6
3
Input offset current
0.1
1
Open loop gain
1 V < VO < 4 V
60
CMRR
Common mode rejection ratio
1.5 V < VCM < 5.5 V
75
95
PSRR
Power supply rejection ratio
12 V < VCC < 20 V
85
110
IO(sink)
Output sink current
VEAOUT = 1 V
IO(src)
Output source current
VEAOUT = 4 V
High-level output voltage
IEAOUT = −0.5 mA
Low-level output voltage
IEAOUT = −1 mA
Gain bandwidth product
f = 200 kHz
Slew
(1)
4
rate(1)
Ensured by design. Not production tested.
1
μA
A
95
dB
2.5
mA
−1.3
−0.5
4.5
4.7
5
0
0.5
1
6
12
Mhz
6
9
V/μs
V
UC1823A, UC2823A, UC2823B,
UC3823A, UC3823B, UC1825A,
UC2825A, UC2825B, UC3825A, UC3825B
www.ti.com
SLUS334E − AUGUST 1995 − REVISED SEPTEMBER 2010
ELECTRICAL CHARACTERISTICS
TA = −55°C to 125°C for the UC1823A/UC1825A, TA = −40°C to 85°C for the UC2823x/UC2825x, TA = 0°C to 70°C for the UC3823x/UC3825x,
RT = 3.65 kΩ, CT = 1 nF, VCC = 12 V, TA = TJ (unless otherwise noted)
PWM COMPARATOR
IBIAS
Bias current, RAMP
VRAMP = 0 V
−1
Minimum duty cycle
−8
μA
0%
Maximum duty cycle
85%
tLEB
Leading edge blanking time
RLEB = 2 kΩ, CLEB = 470 pF
RLEB
Leading edge blanking resistance
VCLK/LEB = 3 V
VZDC
Zero dc threshold voltage, EAOUT
VRAMP = 0 V
tDELAY
Delay-to-output time(1)
VEAOUT = 2.1 V, VILIM = 0 V to 2 V step
300
375
450
ns
8.5
10.0
11.5
kΩ
1.10
1.25
1.4
V
50
80
ns
20
μA
CURRENT LIMIT / START SEQUENCE / FAULT
ISS
Soft-start charge current
VSS
Full soft-start threshold voltage
IDSCH
Restart discharge current
ISS
Restart threshold voltage
IBIAS
ILIM bias current
ICL
Current limit threshold voltage
Overcurrent threshold voltage
Delay-to-output time, ILIM(1)
td
VSS= 2.5 V
8
14
4.3
5
100
250
350
μA
0.3
0.5
V
15
μA
0.95
1
1.05
1.14
1.2
1.26
50
80
IOUT = 20 mA
0.25
0.4
IOUT = 200 mA
1.2
2.2
IOUT = 20 mA
1.9
2.9
2
3
CL = 1 nF
20
45
UC2823B, UC2825B, UC3825B, UC3825B
16
17
9.6
VSS= 2.5 V
VILIM = 0 V to 2 V step
VILIM = 0 V to 2 V step
V
V
ns
OUTPUT
Low level output saturation voltage
Low-level
High level output saturation voltage
High-level
tr,
tf
Rise/fall time(1)
IOUT = 200 mA
V
ns
UNDERVOLTAGE LOCKOUT (UVLO)
Start threshold voltage
UC1823A, UC1825A, UC2823A, UC2825A
UC3825A, UC3825A
8.4
9.2
Stop threshold voltage
UC2823B, UC2825B, UC3825B, UC3825B
9
10
OVLO hysteresis
UC1823A, UC1825A, UC2823A, UC2825A
UC3825A, UC3825A
0.4
0.8
1.2
UC2823B, UC2825B, UC3825B, UC3825B
5
6
7
100
300
μA
28
36
mA
V
SUPPLY CURRENT
Isu
Startup current
ICC
Input current
(1)
VC = VCC = VTH(start) − 0.5 V
Ensured by design. Not production tested.
5
UC1823A, UC2823A, UC2823B,
UC3823A, UC3823B, UC1825A,
UC2825A, UC2825B, UC3825A, UC3825B
www.ti.com
SLUS334E − AUGUST 1995 − REVISED SEPTEMBER 2010
APPLICATION INFORMATION
The oscillator of the UC3823A, UC3823B, UC3825A, and UC3825B is a saw tooth. The rising edge is governed by a current
controlled by the RT pin and value of capacitance at the CT pin (CCT). The falling edge of the sawtooth sets dead time for
the outputs. Selection of RT should be done first, based on desired maximum duty cycle. CT can then be chosen based
on the desired frequency (RT) and DMAX. The design equations are:
RT +
3V
(10 mA) ǒ1 * DMAXǓ
CT +
ǒ1.6
ǒR T
D MAXǓ
fǓ
(1)
Recommended values for RT range from 1 kΩ to 100 kΩ. Control of DMAX less than 70% is not recommended.
UDG−95102
Figure 1. Oscillator
OSCILLATOR FREQUENCY
vs
TIMING RESISTANCE
10 M
MAXIMUM DUTY CYCLE
vs
TIMING RESISTANCE
100
DMAX − Maximum Duty Cycle − %
f − Frequency − Hz
95
1M
100 k
10 k
1k
10 k
RT − Timing Resistance − W
Figure 2
6
90
85
80
75
70
100 k
1k
10 k
RT − Timing Resistance − W
Figure 3
100 k
UC1823A, UC2823A, UC2823B,
UC3823A, UC3823B, UC1825A,
UC2825A, UC2825B, UC3825A, UC3825B
www.ti.com
SLUS334E − AUGUST 1995 − REVISED SEPTEMBER 2010
LEADING EDGE BLANKING
The UC3823A, UC2823B, UC3825A, and UC3825B perform fixed frequency pulse width modulation control. The
UC3823A, and UC3823B outputs operate together at the switching frequency and can vary from zero to some value less
than 100%. The UC3825A and UC3825B outputs are alternately controlled. During every other cycle, one output is off.
Each output then switches at one-half the oscillator frequency, varying in duty cycle from 0 to less than 50%.
To limit maximum duty cycle, the internal clock pulse blanks both outputs low during the discharge time of the oscillator.
On the falling edge of the clock, the appropriate output(s) is driven high. The end of the pulse is controlled by the PWM
comparator, current limit comparator, or the overcurrent comparator.
Normally the PWM comparator senses a ramp crossing a control voltage (error amplifier output) and terminates the pulse.
Leading edge blanking (LEB) causes the PWM comparator to be ignored for a fixed amount of time after the start of the
pulse. This allows noise inherent with switched mode power conversion to be rejected. The PWM ramp input may not
require any filtering as result of leading edge blanking.
To program a leading edge blanking (LEB) period, connect a capacitor, C, to CLK/LEB. The discharge time set by C and
the internal 10-kΩ resistor determines the blanked interval. The 10-kΩ resistor has a 10% tolerance. For more accuracy,
an external 2-kΩ 1% resistor (R) can be added, resulting in an equivalent resistance of 1.66 kΩ with a tolerance of 2.4%.
The design equation is:
t LEB + 0.5
ǒR ø 10 kWǓ
C
(2)
Values of R less than 2 kΩ should not be used.
Leading edge blanking is also applied to the current limit comparator. After LEB, if the ILIM pin exceeds the 1-V threshold,
the pulse is terminated. The overcurrent comparator, however, is not blanked. It catches catastrophic overcurrent faults
without a blanking delay. Any time the ILIM pin exceeds 1.2 V, the fault latch is set and the outputs driven low. For this
reason, some noise filtering may be required on the ILIM pin.
UDG−95105
Figure 4. Leading Edge Blanking Operational Waveforms
7
UC1823A, UC2823A, UC2823B,
UC3823A, UC3823B, UC1825A,
UC2825A, UC2825B, UC3825A, UC3825B
www.ti.com
SLUS334E − AUGUST 1995 − REVISED SEPTEMBER 2010
UVLO, SOFT-START AND FAULT MANAGEMENT
Soft-start is programmed by a capacitor on the SS pin. At power up, SS is discharged. When SS is low, the error amplifier
output is also forced low. While the internal 9-μA source charges the SS pin, the error amplifier output follows until closed
loop regulation takes over.
Anytime ILIM exceeds 1.2 V, the fault latch is set and the output pins are driven low. The soft-start cap is then discharged
by a 250-μA current sink. No more output pulses are allowed until soft-start is fully discharged and ILIM is below 1.2 V. At
this point the fault latch resets and the chip executes a soft-start.
Should the fault latch get set during soft-start, the outputs are immediately terminated, but the soft-start capacitor does not
discharge until it has been fully charged first. This results in a controlled hiccup interval for continuous fault conditions.
UDG−95106
Figure 5. Soft-Start and Fault Waveforms
ACTIVE LOW OUTPUTS DURING UVLO
The UVLO function forces the outputs to be low and considers both VCC and VREF before allowing the chip to operate.
UDG−95108
Figure 6. Output Voltage vs Output Current
8
UDG−95106
Figure 7. Output V and I During UVLO
UC1823A, UC2823A, UC2823B,
UC3823A, UC3823B, UC1825A,
UC2825A, UC2825B, UC3825A, UC3825B
www.ti.com
SLUS334E − AUGUST 1995 − REVISED SEPTEMBER 2010
CONTROL METHODS
Current Mode
Voltage Mode
UDG−95110
UDG−95109
.
Figure 8. Control Methods
SYNCHRONIZATION
The oscillator can be synchronized by an external pulse inserted in series with the timing capacitor. Program the free
running frequency of the oscillator to be 10% to 15% slower than the desired synchronous frequency. The pulse width
should be greater than 10 ns and less than half the discharge time of the oscillator. The rising edge of the CLK/LEB pin
can be used to generate a synchronizing pulse for other chips. Note that the CLK/LEB pin no longer accepts an incoming
synchronizing signal.
UDG−95111
Figure 9. General Oscillator Synchronization
UDG−95113
Figure 10. Two Unit Interface
UDG−95112
Figure 11. Operational Waveforms
9
UC1823A, UC2823A, UC2823B,
UC3823A, UC3823B, UC1825A,
UC2825A, UC2825B, UC3825A, UC3825B
www.ti.com
SLUS334E − AUGUST 1995 − REVISED SEPTEMBER 2010
HIGH CURRENT OUTPUTS
Each totem pole output of the UC3823A and UC3823AB, UC3825A, and UC3825B can deliver a 2-A peak current into a
capacitive load. The output can slew a 1000-pF capacitor by 15 V in approximately 20 ns. Separate collector supply (VC)
and power ground (PGND) pins help decouple the device’s analog circuitry from the high-power gate drive noise. The use
of 3-A Schottky diodes (1N5120, USD245, or equivalent) as shown in the Figure 13 from each output to both VC and PGND
are recommended. The diodes clamp the output swing to the supply rails, necessary with any type of inductive/capacitive
load, typical of a MOSFET gate. Schottky diodes must be used because a low forward voltage drop is required. DO NOT
USE standard silicon diodes.
Although they are single-ended devices, two output drivers are available on the UC3823A and UC3823B devices. These
can be paralleled by the use of a 0.5 Ω (noninductive) resistor connected in series with each output for a combined peak
current of 4 A.
UDG−95114
Figure 12. Power MOSFET Drive Circuit
GROUND PLANES
Each output driver of these devices is capable of 2-A peak currents. Careful layout is essential for correct operation of the
chip. A ground plane must be employed. A unique section of the ground plane must be designated for high di/dt currents
associated with the output stages. This point is the power ground to which the PGND pin is connected. Power ground can
be separated from the rest of the ground plane and connected at a single point, although this is not necessary if the high
di/dt paths are well understood and accounted for. VCC should be bypassed directly to power ground with a good high
frequency capacitor. The sources of the power MOSFET should connect to power ground as should the return connection
for input power to the system and the bulk input capacitor. The output should be clamped with a high current Schottky diode
to both VCC and PGND. Nothing else should be connected to power ground.
VREF should be bypassed directly to the signal portion of the ground plane with a good high frequency capacitor. Low
ESR/ESL ceramic 1-mF capacitors are recommended for both VCC and VREF. All analog circuitry should likewise be
bypassed to the signal ground plane.
10
UC1823A, UC2823A, UC2823B,
UC3823A, UC3823B, UC1825A,
UC2825A, UC2825B, UC3825A, UC3825B
www.ti.com
SLUS334E − AUGUST 1995 − REVISED SEPTEMBER 2010
UDG−95115
Figure 13. Ground Planes Diagram
OPEN LOOP TEST CIRCUIT
This test fixture is useful for exercising many functions of this device family and measuring their specifications. As with any
wideband circuit, careful grounding and bypass procedures should be followed. The use of a ground plane is highly
recommended.
UDG−95116
Figure 14. Open Loop Test Circuit Schematic
11
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