PB50
PB50U 1
PB50
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 180V P-P
DESCRIPTION
The PB50 is a high voltage, high current amplier designed
to provide voltage and current gain for a small signal, general
purpose op amp. Including the power booster within the feed-
back loop of the driver amplier results in a composite amplier
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, provid-
ing symmetrical output impedance and eliminating secondary
breakdown limitations imposed by Bipolar Junction Transis-
tors. 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 congurations, but can be accomplished
with a single external capacitor. Although the booster can
be congured quite simply, enormous exibility is provided
through the choice of driver amplier, current limit, supply
voltage, voltage gain, and compensation.
This hybrid circuit utilizes a beryllia (BeO) substrate, thick
lm resistors, ceramic capacitors and semiconductor chips to
maximize reliability, minimize size and give top performance.
Ultrasonically bonded aluminum wires provide reliable inter-
connections 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.
TYPICAL APPLICATION
Figure 1. Inverting composite amplier.
OP
AMP
PB50
CF
RF
VIN RI
+15V
–15V
IN
COM
+Vs
–Vs
RCL
OUT
CC
RG
RL
EQUIVALENT SCHEMATIC
EXTERNAL CONNECTIONS
3
1
2
6
8
5
4
7
IN
GAIN
COM
COMP
Q1
Q4
Q2
Q3
Q5
Q6
Q7
Q8
Q10
Q9
+Vs
OUT
CL
–Vs
6.2K
50K 3.1K
CL +V
S
IN
COM
–V
S
GAIN
COMP
OUT
TOP VIEW
R
G
R
CL
1
23
4
5
6
7
8
C
C
8-PIN TO-3
PACKAGE STYLE CE
Power Booster Amplifier
PB50
Copyright © Cirrus Logic, Inc. 2012
(All Rights Reserved)
www.cirrus.com
MAR 2012
APEX − PB50UREVL
PB50
2 PB50U
ABSOLUTE MAXIMUM RATINGS SUPPLY VOLTAGE, +VS to –VS 200V
OUTPUT CURRENT, within SOA 2A
POWER DISSIPATION, internal at TC = 25°C1 35W
INPUT VOLTAGE, referred to common ±15V
TEMPERATURE, pin solder—10 sec max 350°C
TEMPERATURE, junction1 150°C
TEMPERATURE, storage –65 to +150°C
OPERATING TEMPERATURE RANGE, case –55 to +125°C
SPECIFICATIONS
PARAMETER TEST CONDITIONS2 MIN TYP MAX UNITS
INPUT
OFFSET VOLTAGE, initial ±.75 ±1.75 V
OFFSET VOLTAGE, vs. temperature Full temperature range –4.5 –7 mV/°C
INPUT IMPEDANCE, DC 25 50 kΩ
INPUT CAPACITANCE 3 pF
CLOSED LOOP GAIN RANGE 3 10 25 V/V
GAIN ACCURACY, internal Rg, Rf AV = 3 ±10 ±15 %
GAIN ACCURACY, external Rf AV = 10 ±15 ±25 %
PHASE SHIFT F = 10kHz, AVCL = 10, CC = 22pF 10 °
F = 200kHz, AVCL = 10, CC = 22pF 60 °
OUTPUT
VOLTAGE SWING Io = 2A VS–11 VS –9 V
VOLTAGE SWING Io = 1A VS–10 VS –7 V
VOLTAGE SWING Io = .1A VS–8 VS –5 V
CURRENT, continuous 2 A
SLEW RATE Full temperature range 50 100 V/µs
CAPACITIVE LOAD Full temperature range 2200 pF
SETTLING TIME to .1% RL = 100Ω, 2V step 2 µs
POWER BANDWIDTH VC = 100Vpp 160 320 kHz
SMALL SIGNAL BANDWIDTH CC = 22pF, AV = 25, Vcc = ±100 100 kHz
SMALL SIGNAL BANDWIDTH CC = 22pF, AV = 3, Vcc = ±30 1 MHz
POWER SUPPLY
VOLTAGE, ±VS3 Full temperature range ±305 ±60 ±100 V
CURRENT, quiescent VS = ±30 9 12 mA
VS = ±60 12 18 mA
VS = ±100 17 25 mA
THERMAL
RESISTANCE, AC junction to case4 Full temp. range, F > 60Hz 1.8 2.0 °C/W
RESISTANCE, DC junction to case Full temp. range, F < 60Hz 3.2 3.5 °C/W
RESISTANCE, junction to air Full temperature range 30 °C/W
TEMPERATURE RANGE, case Meets full range specications –25 25 85 °C
NOTES: 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).
2. The power supply voltage specied under typical (TYP) applies, TC = 25°C unless otherwise noted.
3. +VS and –VS denote the positive and negative supply rail respectively.
4. Rating applies if the output current alternates between both output transistors at a rate faster than 60Hz.
5. +VS must be at least 15V above COM, –VS must be at least 30V below COM.
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.
CAUTION
PB50
PB50U 3
–25 0 25 50 75 100
0
10
POWER DERATING
INTERNAL POWER DISSIPATION, P(W)
–25 25 125
0
1.5
2
CURRENT LIMIT
1
.5
SLEW RATE, SR (V/µs)
100 10M
FREQUENCY, F (Hz)
0
60
SMALL SIGNAL RESPONSE
OPEN LOOP GAIN, A (dB)
20
40
80
1K 10K 10M
–10
20
30
SMALL SIGNAL RESPONSE
10
1K 10K 10M
FREQUENCY, F (Hz)
–180
1K 10K 30K 1M
FREQUENCY, F (Hz)
11
360
POWER RESPONSE
VQ (V), P-P
22
90
180
300 30K
FREQUENCY, F (Hz)
.01
.03
1
HARMONIC DISTORTION
DISTORTION, THD (%)
.3
300 3K 30K
FREQUENCY, F (Hz)
.001
.1
HARMONIC DISTORTION
DISTORTION, THD (%)
.01
.03
–25 75
CASE TEMPERATURE, TC (°C)
0
QUIESCENT CURRENT
20
1000 25
INPUT OFFSET VOLTAGE
INPUT OFFSET VOLTAGE, VOS (V)
.01 .02 2
OUTPUT CURRENT, IO (A)
2
10
OUTPUT VOLTAGE SWING
VOLTAGE DROP FROM SUPPLY, V
S
- V
O
(V)
8
3K 100K 300K 1K
.003
SLEW RATE VS. TEMP.
0
300
400
100
200
0 50 75 100
40
SMALL SIGNAL RESPONSE
100K
1K 3K 10K
.1 .2 1
6
-1.5
1K 10K 100K 1M
125
20
30
100K 1M
FREQUENCY, F (Hz)
CLOSED LOOP GAIN, A (dB) CURRENT LIMIT, ILIM (A)
4
50 125
5
10
15
-1
–.5
0
.5
1M
–135
–90
–45
0
45
10K
.1
CASE TEMPERATURE, TC (°C) CASE TEMPERATURE, TC (°C)
R
CL
= .68Ω
RCL = 1.5Ω
OPEN LOOP PHASE, Ф (°)
–180
–135
–90
–45
0
R
CL
= .33Ω
CLOSED LOOP PHASE, Ф (°)
0
RCL = .27Ω
AVCL = 10
AVCL = 3
AVCL = 25
AVCL = 25
AVCL = 10
AVCL = 3
VO +
VO –
QUIESCENT CURRENT, IO (mA)
Vs = ±60V
Vs = ±30V
CASE TEMPERATURE, TC ( C) OR VS (V)
–25 75 1000 25 50 125
Vs = ±100V
TEMP.
–25 75
CASE TEMPERATURE, TC (°C)
1000 25 50 125
+SLEW
–SLEW
SUPPLY
CC = 22pF
RL = 25Ω
RL = 25Ω
RL = 1KΩ RL = 1KΩ
NO DRIVER
VS = ±60V
VO = 80VP-P
DRIVER = TL070
VS = ±60V
VO = 95VP-P
CC = 22pF
PB50
4 PB50U
GENERAL
Please read Application Note 1 "General Operating Con-
siderations" which covers stability, supplies, heat sinking,
mounting, current limit, SOA interpretation, and specication
interpretation. Visit www.Cirrus.com for design tools that help
automate tasks such as calculations for stability, internal power
dissipation, current limit; heat sink selection; Apex Precision
Power’s complete Application Notes library; Technical Seminar
Workbook; and Evaluation Kits.
CURRENT LIMIT
For proper operation, the current limit resistor (RCL) must be
con nected as shown in the external 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=
.65/RCL + .010, –IL = .65/RCL.
SAFE OPERATING AREA (SOA)
NOTE: The output stage is protected against transient yback.
However, for protection against sustained, high energy yback,
external fast-recovery diodes should be used.
COMPOSITE AMPLIFIER CONSIDERATIONS
Cascading two ampliers within a feedback loop has many
advantages, but also requires careful consideration of several
amplier and system parameters. The most important of these
are gain, stability, slew rate, and output swing of the driver.
Operating the booster amplier in higher gains results in a
higher slew rate and lower output swing requirement for the
driver, but makes stability more difficult to achieve.
GAIN SET
RG = [ (Av-1) • 3.1K] – 6.2K
RG + 6.2K
Av = +1
3.1K
The booster’s closed-loop gain is given by the equation
above. The composite amplier’s closed loop gain is determined
by the feedback network, that is: –Rf/Ri (inverting) or 1+Rf/Ri
(non-inverting). The driver amplier’s “effective gain” is equal
to the composite gain divided by the booster gain.
Example: Inverting conguration (gure 1) with
R i = 2K, R f = 60K, R g = 0 :
Av (booster) = (6.2K/3.1K) + 1 = 3
Av (composite) = 60K/2K = - 30
Av (driver) = - 30/3 = -10
STABILITY
Stability can be maximized by observing the following
guidelines:
1. Operate the booster in the lowest practical gain.
2. Operate the driver amplier in the highest practical effective
gain.
3. Keep gain-bandwidth product of the driver lower than the
closed loop bandwidth of the booster.
4. 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 congurations. 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 conguration 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.
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 = 33K, RI = 3.3K, RG = 22K
Table 1:
Typical values for case where op amp effective gain = 1.
Figure 2. Non-inverting composite amplier.
SLEW RATE
The slew rate of the composite amplier 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.
10 20 30 40 50 100 200 300
SUPPLY TO OUTPUT DIFFERENTIAL VOLTAGE V
S
— V
O
(V)
OUTPUT CURRENT FROM +V
S
OR –V
S
(A)
1
2
3
.1
STEADY STATE T = 85°C
C
t = 50ms
t = 100ms
STEADY STATE T = 25°C
C
STEADY STATE T = 125°C
C
t = 200ms
SOA
OP
AMP
PB50
C
F
R
F
R
I
+15V
–15V
IN
COM
+Vs
–Vs
R
CL
OUT
C
C
R
G
R
L
V
IN
GAIN
COMP
C
CH
PB50
PB50U 5
CONTACTING CIRRUS LOGIC SUPPORT
For all Apex Precision Power product questions and inquiries, call toll free 800-546-2739 in North America.
For inquiries via email, please contact apex.support@cirrus.com.
International customers can also request support by contacting their local Cirrus Logic Sales Representative.
To nd the one nearest to you, go to www.cirrus.com
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