Analog Devices Linear Technology DC2329A Demo Manual

17V , Dual 3.5A Synchronous Step-Down Regulator
IN
Description
Demonstration circuit DC2329A features the
LTC 7124IUDD: a wide input and output voltage range,
®
high efficiency and power density, dual 3.5A DC/DC step-
down monolithic regulator. The input voltage range of the
DC2329A is 3.1V to 17V. The default setting of V
user selectable from 1.2V, 1.5V and 1.8V at 3.5A max.
The default setting of V
OUT2
3.3V and 5.0V at 3.5A max. The default switching fre-
quency of DC2329A is set at 1MHz typical. Programmable
peak current limit of either 2.6A or 5A can be achieved
by changing the setting of ILIM pin. Selectable internal
or external loop compensation allows users more options
to optimize the loop bandwidth and output load transient
response. A user-selectable mode input is provided to
allow users to trade off ripple noise for light load effi-
ciency: pulse skipping mode (PS) or Burst Mode
of operation delivers higher efficiency at light load while
forced continuous conduction mode (FCM) is preferred
performance summary
SYMBOL PARAMETER
V Input Voltage Range
IN
V , Default Output Voltages
OUT1
V
OUT2
Default Switching Frequency
I , Maximum Continuous Output
OUT1
I Current I per Channel
OUT2 OUT
Efficiency
Thermal Performance
(Peak Temperature)
V Dynamic Load Transient Response f
OUT1(P-P)
V
OUT2(P-P)
V Output Voltage Ripples
OUT1(P-P)
V (Peak-to-Peak)
OUT2(P-P)
with Ultra-Low Quiescent Current
OUT1
is user selectable from 2.5V,
(BM)
®
Specifications are at T
CONDITIONS
f = 1MHz, V = 3.1V to 17V,
SW IN
I = 0A to 3.5A
LOAD
Programmed frequency with an external resistor from RT to GND
f = 1MHz, V = 3.1V to 17V (V
SW IN
V = 1.2V, 1.5V, 1.8V, 2.5V, 3.3V, 5V
OUT
f = 1MHz, V = 12V
SW IN
V = 1.8V at I
OUT1 OUT1
f = 1MHz, V = 12V
SW IN
V = 1.8V, V
OUT1 OUT2
T = 25°C, No Heat Sink, No Forced Airflow
A
= 1MHz, V = 12V, Mode = FCM
SW IN
V = 1.8V, I
OUT1 OUT1_STEP
V = 2.5V, I
OUT2 OUT2_STEP
C = 1x100µF + 1x47µF per Channel
OUT
f = 1MHz, V = 12V
SW IN
V = 1.8V at I
OUT1 OUT1
C = 1x100µF + 1x47µF per Channel
OUT
DEMO MANUAL DC2329A
for noise sensitive applications. The Mode pin can also
be used to synchronize the switching frequency to an
external clock. Programmable switching frequency ranges
from 500kHz to 4MHz with a ±25% synchronization cap-
is ture range. The constant frequency, peak current mode
control architecture and integrated internal or optional
external control loop compensation network, allows very
fast transient response to line and load changes while
maintaining loop stability.
The LTC7124 is available in a thermally enhanced, low
profile 24-lead 3mm x 5mm QFN package.
It is recommended to read the data sheet and demo man-
ual of the LTC7124 prior to using or making any changes
to the DC2329A.
Design files for this circuit board are available at
http://www.linear.com/demo/DC2329A
L, LT, LTC, LTM, Linear Technology, Burst Mode and the Linear logo are registered trademarks
of Analog Devices, Inc. All other trademarks are the property of their respective owners.
= 25°C
A
< V )
OUT IN
= 3.5A, V = 2.5V at I = 3.5A
OUT2 OUT2
= 2.5V, I = 3.5A per Channel
OUT
= 1.75A to 3.5A,
= 1.75A to 3.5A
= 3.5A, V = 2.5V at I = 3.5A
OUT2 OUT2
LTC7124
VALUE
3.1V to 17V
1.8V ±2%
2.5V ±2%
1MHz ±10%
3.5A
Channel 1: 83.7% (Figure 3)
Channel 2: 87.1% (Figure 3)
LTC7124: 71.1°C
L1: 54.8°C
L2: 57°C
(Figure 5)
V = 150mV (Figure 7a)
OUT1(P-P)
V = 181mV (Figure 7b)
OUT2(P-P)
V = 6.6mV (Figure 8a)
OUT1(P-P)
V = 5.3mV (Figure 8b)
OUT2(P-P)
dc2329af
1