Datasheet
VDD
NIN n
PIN n
VPP
VPF
VDN
Input
Buffer
VNN
HVGND
AGND
Level
Shifter
VLL
EN
OTP
Temp
Sensor
Buffer
Buffer
Level
Shifter
Down
Vout n
MOD
VSUB
VNF
Active
Damper
Level
Shifter
Up
Regulates
LM96551
www.ti.com
SNAS511B –OCTOBER 2011–REVISED MAY 2013
DC Characteristics
Unless otherwise stated, the following conditions apply.
VLL = +3.3V, VDD = −VDN = 10V, VSUB = −55V, VPP = −VNN = 50V, T
A
= 25°C,
Symbol Parameter Conditions Min Typ Max Unit
V
IL
Low Input “LO” threshold 1 V
V
IH
High Input “HI” threshold 2.3 V
I
IN
input current 1 µA
Overview
The LM96551 pulser provides an 8-channel transmit side solution for medical ultrasound applications suitable for
integration 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 Texas Instrument’s
companion LM965XX chipset.
Figure 3. Block Diagram of High-Voltage Pulser Channel
A functional block diagram of the LM96551 is shown in Figure 3. 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 (V
OUT
n), respectively. The output pins V
OUT
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.
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