Medical Electronics ICs
Volume 8, Issue 4 YOUR SEMICONDUCTOR SOLUTIONS RESOURCE

Optimize Power Distribution in High Performance Imaging Systems

High performance CT, MRI, and ultrasound systems require clean, low noise power along the entire signal acquisition path. Digital image data is processed in a DSP or other proprietary algorithm processor to enhance image quality and combine various image slices. The power requirements for these digital circuits include the application of many supply voltages with very tight regulation accuracy on the processor core voltage. Proper voltage monitoring of the processor is essential in case disruptive events cause a watchdog output to cease operation.

The ADP1707 and ADP1720 low noise, low dropout linear regulators are compact devices with as little as 20 µV rms in the 100 Hz to 100 kHz frequency range, and ripple rejection up to 60 dB at 1 kHz. Enable pins allow for power domain optimization and voltage tracking inputs to optimize system supply sequencing. The ADP2105 and ADP2107 are high efficiency switching regulators and controllers optimized for load step response and precise core voltage generation. The ADM13305 is a dual processor supervisor with an on-chip watchdog reset timer that monitors and controls system voltages. The watchdog timer will reset the microprocessor if it fails to strobe within the preset timeout period.

High Performance Imaging

Switching Controllers

Part
Number
Power
Input
(V)
VOUT Adj Range Supply Current
(Max)
Switching
Frequency
VIN/VOUT
Change
Package
ADP1621 Low as 1 VIN to 30 V 3 mA 100 kHz to 1.5 MHz Step-up, invert 8-lead MSOP
ADP1864 3.15 to 14 0.8 V to VIN 350 µA 580 kHz Step-down 6-lead TSOT

Linear Regulators

Part
Number
VOUT Preset (V) IOUT (Max) VIN Range
(VMIN to VMax)
VDROPOUT @
Rated IOUT (mV)
IOUT Setpoint ACC
(mA)
Package
ADP1706 16 V, 0.75
to 3.3
1 A 2.5 to 5.5 600 to 630 1% @ IOUT = 10 8-lead LFCSP,
8-lead SOIC
ADP1720 3.3, 5.0, adj 1.225 to 5.0 50 mA 4.0 to 28 55 to 480 0.5% @ IOUT = 0.1 8-lead MSOP

Switching Regulators

Part
Number
VIN
Range (V)
VOUT
Preset Options (V)
VOUT Adj
Options
IOUT Max (A) Switching
Frequency (MHz)
Package
ADP2105 2.7 to 5.5 1.21, 0.5, 1.8, 3.3 0.8 V to VIN 1 1.2 16-lead LFCSP
ADP2107 2.7 to 5.5 1.2, 1.5, 1.8, 3.3 0.8 V to VIN 2 1.2 16-lead LFCSP

Multivoltage Supervisor

Part
Number
Number of
Monitored Voltages
Reset Threshold (V) Reset Output
Stage
Manual Reset
Capability
Watchdog
Timeout (ms)
Package
ADM13305 2 0.6 (adj),1.68, 2.25, 2.93, 4.55; RS, RS/push-pull Yes 1.6 8-lead
SOIC

The ADIsimPower voltage regulator design tool supports buck converter designs optimized for efficiency, PCB space, cost, or part count. Simply enter design parameters and select a design goal. The tool then calculates optimal values to produce a complete schematic, BOM, efficiency plot, and performance summary. To begin, visit www.analog.com/ADIsimPower.

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