PB50
Power Booster Amplifier
RoHS
COMPLIANT
FEATURES
•
•
•
•
•
•
•
Wide Supply Range — ±30V to ±100V
High Output Current — Up to 2A Continuous
Voltage and Current Gain
High Slew Rate —50V/µs Minimum
Programmable Output Current Limit
High Power Bandwidth — 160 kHz Minimum
Low Quiescent Current — 12mA Typical
APPLICATIONS
•
•
•
High Voltage Instrumentation
Electrostatic Transducers & Deflection
Programmable Power Supplies up to 180VP-P
DESCRIPTION
The PB50 is a high voltage, high current amplifier designed to provide voltage and current gain for a small
signal, general purpose op amp. Including the power booster within the feedback loop of the driver amplifier
results in a composite amplifier with the accuracy of the driver and the extended output voltage range and
current capability of the booster. The PB50 can also be used without a driver in some applications, requiring
only an external current limit resistor to function properly.
The output stage utilizes complementary MOSFETs, providing symmetrical output impedance and eliminating secondary breakdown limitations imposed by Bipolar Junction Transistors. Internal feedback and gainset resistors are provided for a pin-strappable gain of 3. Additional gain can be achieved with a single external
resistor. Compensation is not required for most driver/gain configurations, but can be accomplished with a
single external capacitor. Although the booster can be configured quite simply, enormous flexibility is provided through the choice of driver amplifier, current limit, supply voltage, voltage gain, and compensation.
This hybrid circuit utilizes a beryllia (BeO) substrate, thick film resistors, ceramic capacitors and semiconductor chips to maximize reliability, minimize size and give top performance. Ultrasonically bonded aluminum wires provide reliable interconnections at all operating temperatures. The 8-pin TO-3 package is
electrically isolated and hermetically sealed using one-shot resistance welding. The use of compressible isolation washers voids the warranty.
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© Apex Microtechnology Inc.
All rights reserved
Aug 2015
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TYPICAL CONNECTIONS
Figure 1: Typical Connections
2
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PINOUT AND DESCRIPTION TABLE
Figure 2: External Connections
Pin Number
Name
1
OUT
The output. Connect this pin to load and to the feedback resistors.
2
CL
Connect to the current limit resistor. Output current flows into/out of this pin
through RCL. The output pin and the load are connected to the other side of RCL.
3
+Vs
The positive supply rail.
4
IN
The input.
5
GND
Ground. Connect to same ground as referenced by input amplifier.
6
-Vs
The negative supply rail.
7
GAIN
Gain resistor pin. Connect RGAIN between GAIN and OUT. This will specify the gain
for the power booster itself, not the composite amplifier. See applicable section.
8
CC
Compensation capacitor connection. Select value based on Phase Compensation.
See applicable section.
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Description
3
PB50
SPECIFICATIONS
The power supply voltage specified under typical (TYP) applies, TC = 25°C unless otherwise noted.
ABSOLUTE MAXIMUM RATINGS
Parameter
Symbol
Supply Voltage, total
Output Current, within SOA
Power Dissipation, internal @ Tc
= 25°C1
Max
Units
+Vs to -Vs
200
V
IO
2
A
PD
35
W
+15
V
350
°C
150
°C
-65
+150
°C
-55
+125
°C
Vcm
Input Voltage, referred to common
Min
-15
Temperature, pin solder, 10s max.
Temperature, junction
1
TJ
Temperature, storage
TC
Operating Temperature Range, case
1. Long term operation at the maximum junction temperature will result in reduced product life. Derate internal power dissipation to achieve high MTTF (Mean Time to Failure).
CAUTION
The PB50 is constructed from MOSFET transistors. ESD handling procedures must be observed.
The internal substrate contains beryllia (BeO). Do not break the seal. If accidentally broken, do
not crush, machine, or subject to temperatures in excess of 850°C to avoid generating toxic
fumes.
INPUT
Parameter
Test Conditions
Min
Offset Voltage, initial
Offset Voltage vs. temperature
Full temp range
Input Impedance, DC
25
Input Capacitance
Closed Loop Gain Range
3
Typ
Max
Units
±.75
±1.75
V
-4.5
-7
mV/°C
50
kΩ
3
pF
10
25
V/V
Gain Accuracy, internal Rg, Rf
AV = 3
±10
±15
%
Gain Accuracy, external Rf
AV = 10
±15
±25
%
F = 10 kHz, AVCL= 10, CC= 22pF
10
°
F =200 kHz, AVCL=10, CC=
22pF
60
°
Phase Shift
4
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OUTPUT
Parameter
Test Conditions
Min
Typ
Max
Units
Voltage Swing
Io = 2A
±VS – 11
±VS – 9
V
Voltage Swing
Io = 1A
±VS – 10
±VS – 7
V
Voltage Swing
Io = 0.1A
±VS – 8
±VS – 5
V
Current, continuous
2
Slew Rate
Full temp range
Capacitive Load
Full temp range
Settling Time to 0.1%
RL = 100 Ω, 2V step
Power Bandwidth
VC = 100Vpp
Small Signal Bandwidth
CC = 22pF, AV = 25, ±VS =
±100V
Small Signal Bandwidth
CC = 22pF, AV = 3, ±VS = ±30V
50
160
A
100
V/µs
2200
pF
2
µs
320
kHz
100
kHz
1
MHz
POWER SUPPLY
Parameter
Min
Typ
Max
Units
±30 2
±60
±100
V
VS = ±30
9
12
mA
VS = ±60
12
18
mA
VS = ±100
17
25
mA
Typ
Max
Units
Full temp range, F > 60 Hz
1.8
2
°C/W
Resistance, DC junction to case
Full temp range, F < 60 Hz
3.2
3.5
°C/W
Resistance, junction to air
Full temp range
30
Temperature Range, case
Meets full range specifications
Voltage, ±VS 1
Current, quiescent
Test Conditions
Full temp range
1. +VS and –VS denote the positive and negative supply rail respectively.
2. +VS must be at least 15V above COM, –VS must be at least 30V below COM.
THERMAL
Parameter
Resistance, AC junction to case 1
Test Conditions
Min
-25
25
°C/W
85
°C
1. Rating applies if the output current alternates between both output transistors at a rate faster than 60 Hz.
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TYPICAL PERFORMANCE GRAPHS
Figure 3: Power Derating
Figure 4: Current Limit
2
RC с
L
Ϭ͘ϯϯɏ
30
Current Limit, ILIM (A)
20
10
0
-25
0
25
50
75
100
1.5
RCLсϬ͘Ϯϳɏ
RC с
Ϭ͘ϲ
L
1
ϴɏ
RCL сϭ͘ϱɏ
0.5
0
-25
125
0
Case Temperature, TC (°C)
75
100
125
Figure 6: Small Signal Response
(Open Loop Gain and Phase)
Open Loop Gain, A (dB)
10
Voltage Drop From Supply, VS - VO (V)
50
Case Temperature, TC (°C)
Figure 5: Output Voltage Swing
8
6
VO –
4
80
0
60
-45
40
-90
Phase
Gain
20
-135
VO +
2
0.01 0.02
0.1
0.2
Output Current, IO (A)
6
25
Open Loop Phase, ˇ;ΣͿ
/ŶƚĞƌŶĂůWŽǁĞƌŝƐƐŝƉĂƟŽŶ͕W;t)
40
1
2
0
100
1k
10k
100k
1M
-180
10M
Frequency, F (Hz)
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PB50
Figure 7: Small Signal Response
(Closed Loop Gain)
Figure 8: Small Signal Response
(Closed Loop Phase)
30
0
AVCL = 3
Closed Loop Phase, ˇ;ΣͿ
Closed Loop Gain, A (dB)
AVCL = 25
20
AVCL = 10
10
AVCL = 3
0
-45
AVCL = 10
AVCL = 25
-90
-135
CC = 22pF
-10
1k
10k
CC = 22pF
1M
100k
-180
1k
10M
10k
Frequency, F (Hz)
Figure 10: Input Offset Voltage
0.5
Vs = ±100V
/ŶƉƵƚKīƐĞƚsŽůƚĂŐĞ͕sOS (sͿ
Quiescent Current, IO (mA)
20
15
Vs = ±60V
Vs = ±30V
10
5
0
25
50
75
100
Case Temperature, TC (°C)
PB50U Rev N
10M
Frequency, F (Hz)
Figure 9: Quiescent Current
0
-25
1M
100k
125
0
d DW͘
-0.5
-1
-1.5
-25
^hWW>z
0
25
50
75
100
125
ĂƐĞdĞŵƉĞƌĂƚƵƌĞ͕dC (°Ϳ
7
PB50
Figure 11: Slew Rate vs. Temperature
Figure 12: Power Response
400
360
+SLEW
VQ (V), P-P
Slew Rate, SR (V/μs)
180
300
200
90
45
–SLEW
100
22
0
-25
0
25
50
75
100
11
1k
125
3k
10k
Case Temperature, TC (°C)
1M
0.1
NO DRIVER
VS = ±60V
VO = 80VP-P
ŝƐƚŽƌƟŽŶ͕d,;йͿ
ŝƐƚŽƌƟŽŶ͕d,;йͿ
300k
Figure 14: Harmonic Distortion
1
RLсϮϱɏ
0.1
0.03
0.01
300
RLсϭŬɏ
1k
0.03
Z/s Zсd>ϬϳϬ
VS = ±60V
VO = 95VP-P
RLсϮϱɏ
0.01
0.003
RLсϭŬɏ
3k
10k
Frequency, F (Hz)
8
100k
Frequency, F (Hz)
Figure 13: Harmonic Distortion (No Driver)
0.3
30k
30k
0.001
300
1k
3k
10k
30k
Frequency, F (Hz)
PB50U Rev N
PB50
SAFE OPERATING AREA (SOA)
Note: The output stage is protected against transient flyback. However, for protection against sustained,
high energy flyback, external fast-recovery diodes should be used.
Figure 15: SOA
Output Current From +VS or - VS (A)
3
2
ST
E
1
ST
E
AD
Y
ST
E
AD
Y
t=
ST
AT
E
AD
Y
m
s
s
s
ST
AT
E
ST
AT
E
C
20
50
m
10
0
0m
T
=
C
T
C
T
t=
t=
=
25
85
°C
°C
=
12
5
°C
0.1
10
20
30 40 50
100
200 300
^ƵƉƉůLJƚŽKƵƚƉƵƚŝīĞƌĞŶƟĂů
sŽůƚĂŐĞVS - VO (V)
PB50U Rev N
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PB50
GENERAL
Please read Application Note 1 “General Operating Considerations” which covers stability, supplies, heat
sinking, mounting, current limit, SOA interpretation, and specification interpretation. Visit www.apexanalog.com for Apex Microtechnology’s complete Application Notes library, Technical Seminar Workbook, and
Evaluation Kits.
TYPICAL APPLICATIONS
Figure 16: Typical Applications
CURRENT LIMIT
For proper operation, the current limit resistor (RCL) must be connected as shown in the typical connection diagram. The minimum value is 0.27Ω with a maximum practical value of 47Ω. For optimum reliability
the resistor value should be set as high as possible. The value is calculated as follows: +IL=
0.65V
I CL = -------------- + 0.01A
R CL
0.65V
– I CL = -------------R CL
COMPOSITE AMPLIFIER CONSIDERATIONS
Cascading two amplifiers within a feedback loop has many advantages, but also requires careful consideration of several amplifier and system parameters. The most important of these are gain, stability, slew rate,
and output swing of the driver. Operating the booster amplifier in higher gains results in a higher slew rate
and lower output swing requirement for the driver, but makes stability more difficult to achieve.
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GAIN SET
R G = Av – 1 3.1k – 6.2k
R G + 6.2k
Av = ------------------------ + 1
3.1k
The booster’s closed-loop gain is given by the equation above. The composite amplifier’s closed loop gain
is determined by the feedback network, that is: –Rf/Ri (inverting) or 1+Rf/Ri (non-inverting). The driver amplifier’s “effective gain” is equal to the composite gain divided by the booster gain.
Example: Inverting configuration (figure 1) with
R i = 2 k, R f = 60 k, R gain = 0:
Av (booster) = (6.2 k/3.1 k) + 1 = 3
Av (composite) = 60 k /2 k = - 30
Av (driver) = - 30/3 = -10
STABILITY
1.
2.
3.
4.
Stability can be maximized by observing the following guidelines:
Operate the booster in the lowest practical gain.
Operate the driver amplifier in the highest practical effective gain.
Keep gain-bandwidth product of the driver lower than the closed loop bandwidth of the booster.
Minimize phase shift within the loop.
A good compromise for (1) and (2) is to set booster gain from 3 to 10 with total (composite) gain at least
a factor of 3 times booster gain. Guideline (3) implies compensating the driver as required in low composite
gain configurations. Phase shift within the loop (4) is minimized through use of booster and loop compensation capacitors Cc and Cf when required. Typical values are 5pF to 33pF.
Stability is the most difficult to achieve in a configuration where driver effective gain is unity (ie; total gain
= booster gain). For this situation, Table 1 gives compensation values for optimum square wave response
with the op amp drivers listed.
TABLE 1: TYPICAL VALUES FOR CASE WHERE OP AMP EFFECTIVE GAIN = 1.
DRIVER
CCH
CF
CC
FPBW
SR
OP07
-
22p
22p
4kHz
1.5
741
-
18p
10p
20kHz
7
LF155
-
4.7p
10p
60kHz
>60
LF156
-
4.7p
10p
80kHz
>60
TL070
22p
15p
10p
80kHz
>60
For: RF = 33 k, RI = 3.3 k, RG = 22 k
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PB50
Figure 17: Non-inverting Composite Amplifier
SLEW RATE
The slew rate of the composite amplifier is equal to the slew rate of the driver times the booster gain,
with a maximum value equal to the booster slew rate.
OUTPUT SWING
The maximum output voltage swing required from the driver op amp is equal to the maximum output
swing from the booster divided by the booster gain. The Vos of the booster must also be supplied by the
driver, and should be subtracted from the available swing range of the driver. Note also that effects of Vos
drift and booster gain accuracy should be considered when calculating maximum available driver swing.
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PACKAGE OPTIONS
PACKAGE STYLE CE
NEED TECHNICAL HELP? CONTACT APEX SUPPORT!
For all Apex Microtechnology product questions and inquiries, call toll free 800-546-2739 in North America. For
inquiries via email, please contact apex.support@apexanalog.com. International customers can also request
support by contacting their local Apex Microtechnology Sales Representative. To find the one nearest to you,
go to www.apexanalog.com
IMPORTANT NOTICE
Apex Microtechnology, Inc. has made every effort to insure the accuracy of the content contained in this document. However, the information is
subject to change without notice and is provided "AS IS" without warranty of any kind (expressed or implied). Apex Microtechnology reserves the right
to make changes without further notice to any specifications or products mentioned herein to improve reliability. This document is the property of
Apex Microtechnology and by furnishing this information, Apex Microtechnology grants no license, expressed or implied under any patents, mask
work rights, copyrights, trademarks, trade secrets or other intellectual property rights. Apex Microtechnology owns the copyrights associated with the
information contained herein and gives consent for copies to be made of the information only for use within your organization with respect to Apex
Microtechnology integrated circuits or other products of Apex Microtechnology. This consent does not extend to other copying such as copying for
general distribution, advertising or promotional purposes, or for creating any work for resale.
APEX MICROTECHNOLOGY PRODUCTS ARE NOT DESIGNED, AUTHORIZED OR WARRANTED TO BE SUITABLE FOR USE IN PRODUCTS USED FOR LIFE
SUPPORT, AUTOMOTIVE SAFETY, SECURITY DEVICES, OR OTHER CRITICAL APPLICATIONS. PRODUCTS IN SUCH APPLICATIONS ARE UNDERSTOOD TO BE
FULLY AT THE CUSTOMER OR THE CUSTOMER’S RISK.
Apex Microtechnology, Apex and Apex Precision Power are trademarks of Apex Microtechnology, Inc. All other corporate names noted herein may be
trademarks of their respective holders.
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