LM96550
Ultrasound Transmit Pulser
General Description
Features
The LM96550 is an eight-channel monolithic high-voltage,
high-speed pulse generator for multi-channel medical ultrasound applications. It is well-suited for use with National’s
LM965XX series chipset which offers a complete medical ultrasound solution targeted towards low-power, portable systems.
The LM96550 contains eight high-voltage pulsers with integrated diodes generating ±50V bipolar pulses with peak currents of up to 2A and pulse rates of up to 15 MHz. Advanced
features include low-jitter and low-phase-noise output pulses
ideal for continuous-wave (CW) modes of operation. Active
clamp circuitry is integrated for ensuring low harmonic distortion of the output signal waveform.
The LM96550 also featuers a low-power operation mode and
over-temperature protection (OTP) which are enabled by onchip temperature sensing and power-down logic.
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Applications
Key Specifications
■ Ultrasound Imaging
© 2011 National Semiconductor Corporation
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8-channel high-voltage CMOS pulse generator
Output pulses with ±50V and 2A peak current
Active damper with built-in blocking diodes
Up to 15 MHz operating frequency
Matched delays for rising and falling edges
Low second harmonic distortion allows and improves
harmonic imaging
Continuous-wave (CW) operation down to ±3.3V
Low Phase noise enables Doppler measurements
Output state over-temperature protection
Blocking diodes for direct interface to transducer
2.5V to 5.0V CMOS logic interface
Low-power consumption per channel
Over Temperature Protection
Output voltage
Output peak current
Output pulse rate
Rise/fall delay
matching (max)
Phase Noise
(Fin=5MHz, 1KHz
offset)
Pulser HD2 (5 MHz)
Operating Temp.
301296
±50
±2.0
Up to 15
125°C
0 = Over-temperature
1 = Normal temperature
This pin is open-drain.
4, 5, 6, 7, 54, 55, 56, 57
VPP
Power
Positive high voltage power supply (+3.3V to +50V)
11, 12, 13, 14, 47, 48, 49,
50
VNN
Power
Negative high voltage power supply (-3.3V to -50V)
8, 53
VPF
Power
Positive floating power supply (VPP -10V)
10, 51
VNF
Power
Negative floating power supply (VNN +10V)
18, 43
VDD
Power
Positive level-shifter supply voltage (+10V)
16, 45
VDN
Power
Negative level-shifter supply voltage (-10V)
20, 41
VLL
Power
Logic supply voltage. Hi voltage reference input (+2.5 to +5V)
VSUB
Power
All VSUB pins must be connected to most negative potential of
the IC.
NOTE: The exposed thermal pad is connected to VSUB.
HVGND
Ground
High voltage reference potential (0V)
AGND
Ground
Analog and Logic voltage reference input, logic ground (0V)
0, 15, 46
3, 9, 52, 58, 61, 64, 67, 70,
71, 74, 77, 80
17, 19, 32, 42, 44
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4
Operating Ratings
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Operation Junction Temperature
VPP, −VNN; High-voltage supply
VPF, −VNF; Floating supply
VDD, −VDN; Level-shift supply
VLL, Logic Supply
VSUB, Substrate bias supply
Maximum Junction Temperature (TJMAX)
Storage Temperature Range
Supply Voltage (VDD)
Supply Voltage (VDN)
Supply Voltage (VPP)
Supply Voltage (VPF)
Supply Voltage (VNN)
Supply Voltage (VNF)
Supply Voltage (VSUB)
IO Supply Voltage (VLL)
Voltage at Logic Inputs
+150°C
−40°C to +125°C
–0.3V to +12V
+0.3V and −12V
–0.3V and +55V
VPP −14V
+0.3V and −55V
VNN +14V
−65V
−0.3V to +5.5V
−0.3V to VLL
+0.3V
0°C to + 70°C
+3.3V to +50V
VPP −10V
+9V to 11V
+2.4V to +5.3V
must be most
negative supply
Package Thermal Resistance (θJA)
ESD Tolerance
Human Body Model
Machine Model
Charge Device Model
19.7°C/W
2kV
150V
750V
Analog Characteristics
Unless otherwise stated, the following conditions apply
VLL = +3.3V, VPP = −VNN = 50V, VPF = −VNF = VPP-10V, VDD = −VDN = 10V, VSUB = −55V, RL = 2 KΩ, TA = 25°C, Mode =
LO, EN = HI, Fin=5MHz
Symbol
FOUT
Parameter
Conditions
Min
Output Frequency Range RL = 100Ω
Typ
1
Output Voltage Range
-48.5
Output Current
2% Duty Cycle
Output Current
100% Duty Cycle,
Mode=HI
0.6
HD2
Second harmonic
distortion
RL = 100Ω || CL = 330pF See (Note 2)
-40
RON
Output ON Resistance
100 mA
Output Phase Noise
5MHz carrier, 1kHz offset, Mode=HI,
VPP=-VNN=5V, RL = 100Ω || CL = 330pF
Output clamp
Positive or Negative pulse
Units
15
MHz
+48.5
V
2
7
Pin = Nin = 0
Power Supply Current
En = 0
OPT
Max
Over Temperature
Protection
dBc
11
−114
Ω
dBc/Hz
2
A
VPP
0.7
3
VNN
0.5
4.5
VDD
8
13
VDN
4
7
VLL
25
50
VSUB
1.2
6
VPF
0.1
1.5
VNF
0.1
1.5
VPP
0.7
3
VNN
0.5
4.5
VDD
0.4
2.7
VDN
0.1
2.2
VLL
25
50
VSUB
1.2
6
VPF
0.1
1.5
VNF
0.1
1.5
125
5
A
mA
µA
mA
mA
µA
mA
°C
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LM96550
Absolute Maximum Ratings (Note 1)
LM96550
Symbol
Parameter
Conditions
Min
Typ
Max
Units
σOTP
OTP sigma
3.0
°C
HsysOTP
OTP hysteresis
5.5
°C
AC and Timing Characteristics
Unless otherwise stated, the following conditions apply.
VLL = +3.3V, VDD = −VDN = 10V, VSUB = −55V, VPP = −VNN = 50V, VPF = −VNF = 40V, CL = 330pF, RL = 100 Ω, TA = 25°C,
Fin=5MHz, Mode=LO, EN=HI
Symbol
Parameter
Conditions
Min
Typ
Max
18
26
18
26
tr
Output rise time
tf
Output fall time
tE
Enable time
1
tdr
Delay time on inputs rise
32
39
tdf
Delay time on inputs fall
32
39
| tdr - tdr |
Delay time mismatch
tdm
Delay on mode change
See (Note 2)
See (Note 2)
P-to-N See (Note 2) & 3
Unit
ns
µs
ns
3
µs
1
DC Characteristics
Unless otherwise stated, the following conditions apply.
VLL = +3.3V, VDD = −VDN = 10V, VSUB = −55V, VPP = −VNN = 50V, VPF = −VNF = 40V, TA = 25°C,
Symbol
Parameter
VIL
Low Input “LO” threshold
VIH
High Input “HI” threshold
IIN
input current
Conditions
Min
Typ
2.3
Max
Unit
1
V
V
1
µA
Note 1: Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Ratings are conditions under which operation of the
device is guaranteed to be functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical
Characteristics.
Note 2: VNF = -42V, VPF = 38V
Note 3: The delay time mismatch can be adjust to be less than 0.8ns with the LM96570 duty cycle control function.
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The LM96550 pulser provides an 8-channel transmit side solution for medical ultrasound applications suitable for integra-
30129602
FIGURE 2. Block Diagram of High-Voltage
Pulser Channel
A functional block diagram of the LM96550 is shown in . It has
an input buffer at its CMOS logic interface, which is powered
by VLL (2.5 to 5.0V). When EN=HI, driving a channel’s inputs
(PIN n or NIN n) HI will result in a positive or negative pulse
at the channel’s output pin (VOUT n), respectively. The output
pins VOUT are pulled to either the positive or negative supplies, VPP or VNN by power MOSFETs.
When PIN and NIN are both LO, Vout is actively clamped to
GNDHI at 0V. This clamping reduces harmonic distortions
compared to competing architectures that use bleeding resistors for implementing the return to zero of the output. The
user must avoid the condition in which PIN and NIN are
both HI simultaneously, as this will damage the output
stage!
The impedance of the output stage can be controlled via the
Mode-pin. When the Mode = HI as shown, only one output
transistor pair drives the output resulting in a peak current of
600 mA at VPP = -VNN = 50V. When Mode=LO, a peak-current of 2A is achievable resulting in faster transients at the
output. However, faster output transients can lead to significant overshoot of the output signal. This can be avoided using
the lower drive current option.
Continuous-wave (CW) applications are supported for low
power consumption down to VPP = -VNN = 3.3V with Mode
=HI.
Internally, the CMOS logic input signals are level shifted to
VDD = 10V and VDN = -10V for pulse transmission. The outputs of the level shifter drive the high-voltage P and N drivers
that control the output power MOSFETs, which are supplied
from the positive and negative rails VPP and VNN, respectively. The high-voltage rails are designed for a maximum of
50V; however, they can be operated down to 3.3V. The necessary gate-overdrive voltage levels for the output drivers are
internally generated from the high-voltage rails.
Over-Temperature Protection (OTP) is implemented by continuously monitoring the on-chip temperature. The OTP output (open drain) pin goes LO when the chip temperature
exceeds a critical level. Prior to this event, the user must ensure that the chip is powered down before fatal damage
occurs. In addition to a primary software controlled safety
shutdown, the OTP pin can be also be hard-wired to the EN
pin as a secondary safety measure.
7
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LM96550
tion into multi-channel (128/256 channel) systems. Its flexible,
integrated ±50V pulser architecture enables low-power designs targeting portable systems. A complete system can be
designed using National’s companion LM965XX chipset.
Overview
LM96550
Timing Diagrams
RISE AND FALL TIME
The timing diagram shown in Figure 3 defines the rise and fall
times tr and tf.
30129604
FIGURE 3. Timing Diagram Defining Rise and Fall Times
tr and tf, respectively
INPUT TO OUTPUT DELAY
The timing diagram shown in Figure 4 defines the delays between the input and output signals.
30129605
FIGURE 4. Timing Diagram Defining Input-to-Output Delays Times
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Unless otherwise stated, the following conditions apply.
VLL = +3.3V, VDD = −VDN = 10V, VSUB = −55V, VPP = −VNN = 50V, VPF = VPP-12V, VNF = VNN+8V, CL = 330pF, RL =
100Ω, TA = 25°C, Fin=5MHz, Mode=LO, EN=HI
Return-to-Zero Rise Time (RL = 2KΩ)
Return-to-Zero Fall Time (RL = 2KΩ)
30129609
30129614
Harmonic Distortion (8 pulses)
CW Phase Noise (Mode=HI, VPP=-VNN=5V)
30129611
30129610
Constant 5W Total Power (RL = 300Ω)
100% CW mode, Mode=HI, VSUB=-10V, VPF=-VNF=VPP-10V
Over Temperature Protection
120
15
12
9
CL=150pF
6
CL=330pF
# of Samples
CW Frequency (MHz)
100
80
60
40
20
3
CL=470pF
0
114
0
3
4
5
6
7
8
VPP=-VNN (V)
9
134
OTP Trip Point (°C)
10
30129613
30129612
9
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LM96550
Typical Performance Characteristics
LM96550
Functional Description
Note that the case, PINn = NNn = HI is not allowed as it will damage the output transistors.
Logic inputs
Output
EN
PINn
NINn
Voutn
1
0
0
0V
1
1
0
VPP - 0.7V
1
0
1
VNN + 0.7V
1
1
1
not allowed
0
X
X
0V
Applications
POWER-UP AND POWER-DOWN SEQUENCES
VSUB must always be the most negative supply, i.e., it must be equal to or more negative than the most negative supply, VNN or
VDN. VPF ≥ VPP −14V AND VNF = ≤ VNN +14V at all times.
Power UP Sequence:
1.
2.
3.
Turn ON VSUB, hold EN pin LO
Turn ON VLL
Turn ON VDD, VDN, VPP, VPF, VNN and VNF
Power DOWN Sequence:
1.
2.
3.
Turn OFF VDD, VDN, VPP, VPF, VNN and VNF
Turn OFF VLL
Turn OFF VSUB
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LM96550
Physical Dimensions inches (millimeters) unless otherwise noted
80-Lead LLP Package
NS Package Number SQA80A
11
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LM96550 Ultrasound Transmit Pulser
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