Linear Technology DC2270A Demo Manual

DESCRIPTION
Demonstration circuit 2270A is a dual-channel low noise
bias generator featuring LT3095. The LT3095 generates two
low noise bias supplies from a common input voltage range
from 3V to 20V. Each channel includes a fixed frequency,
peak current mode step-up switching regulator and a low
noise, single resistor programmable linear regulator. The
maximum load current is 50mA for each channel.
Each boost regulator adjusts its output voltage to 2V above
the corresponding linear regulator's output voltage, opti-
mizing power dissipation, PSRR and transient response.
The integrated boost regulator, frequency compensation
and Schottky diodes minimize the external component
count and simplify system design.
The switching frequency can be programmed either via
oscillator resistor or an external clock from 450kHz to
PERFORMANCE SUMMARY
SYMBOL PARAMETER
V Input Voltage Range
IN
V Channel1 Output Voltage
OUT1
V Channel2 Output Voltage
OUT2
I Channel1 Max Output Current
OUT1
I Channel2 Max Output Current
OUT2
f Switching Frequency
SW
V Output Voltage Peak-to-Peak Noise
OUT,P-P
DEMO MANUAL DC2270A
Dual-Channel Low Noise Bias
2MHz. The SYNC pin on the demo board is grounded by
default. To synchronize to an external clock, move JP1
to SYNC and apply the external clock to the SYNC turret.
The R resistor (R2) should be chosen to set the LT3095
T
internal switching frequency to the SYNC frequency.
The LT3095 is available in a thermally enhanced 24-Lead
3mm × 5mm QFN package.
The LT3095 data sheet gives a complete description of
the device, operation and application information. The
data sheet must be read in conjunction with this quick
start guide for demo circuit 2270.
Design files for this circuit board are available at
http://www.linear.com/demo/DC2270A
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
Specifications are at T = 25°C
A
CONDITIONS
R = 100kΩ
T
V = 5V, V = 15V, I = 50mA, f
IN OUT OUT
20MHz BW
Generators
MIN TYP
3
4.9 5
14.7 15
50
50
0.95 1
= 1MHz 65
SW
LT3095
MAX UNITS
20 V
5.1 V
15.3 V
mA
mA
1.05 MHz
µV
dc2270afa
1