Linear Technology DC2169A Demo Manual

Dual 42V Synchronous Monolithic Step-Down
Description
Demonstration circuit 2169A is a dual monolithic step-down
DC/DC switching regulator featuring the
LT8616 is a high efficiency, high speed, dual synchronous
monolithic step-down switching regulator that consumes
only 6.5μA of quiescent current with both channels enabled.
The demo circuit is designed for 5V, 1.5A and 3.3V, 2.5A
outputs. Both channels contain all switches and neces-
sary circuitry to minimize the external components and
solution size. Fast minimum ON time of 35ns enables high
V to low V conversion at high switching frequency.
IN OUT
Independent input voltage, feedback, soft-start and power
good pins for each channel simplify complex power supply
tracking/sequencing requirements.
The inputs of the two channels are connected on the demo
board by default. They can also be separated by removing
the 0Ω resistor (R13) from the board. Each output can
be independently disabled using its own EN/UV pin, while
V must be connected to 3.4V or above even if only
IN1
channel 2 is in use. The demo board has an EMI filter
installed between V and V
IN2
inputs should be tied to V
The switching frequency of both channels can be pro-
grammed either via an oscillator resistor or a common
external clock up to 3MHz.The SYNC pin on the demo
board is grounded by default for Burst Mode
performance summary
SYMBOL PARAMETER
V Channel 1 Input Supply Range
IN1
V Channel 2 Input Supply Range
IN2
V Channel 1 Output Voltage
OUT1
V Channel 2 Output Voltage
OUT2
f Switching Frequency
SW
I Channel 1 Max Output Current
OUT1
I Channel 2 Max Output Current
OUT2
EFE Efficiency at DC
Regulator with 6.5µA Quiescent Current
LT 8616. The
®
. To use the EMI filter, the
EMI
.
EMI
operation.
®
Specifications are at T
CONDITIONS
R = 14.7kΩ
T
V = V = 12V, I
IN1 IN2
DEMO MANUAL DC2169A
To synchronize to an external clock, move JP1 to SYNC/
MODE and apply the external clock to the SYNC/MODE
turret. The R resistor (R5) should be chosen to set the
T
LT8616 internal switching frequency at least 20% below
the lowest synchronization input.
Low ripple Burst Mode operation increases the efficiency
at the light load while keeping the output ripple low.
Figure 1 and Figure 2 show the demo board efficiency for
each channel at 12V input voltage in Burst Mode opera-
tion. Figure 3 shows the temperature rising on DC2169A
demo board with different input voltages under full load
conditions on both channels.
The LT8616 data sheet gives a complete description of the
part, operation and application information. The data sheet
must be read in conjunction with this demo manual for
DC2169A. The LT8616 is assembled in a 28-lead plastic
TSSOP package. Proper board layout is essential for both
low EMI operation and maximum thermal performance.
See the data sheet sections for details.
Design files for this circuit board are available at
http://www.linear.com/demo/DC2169A
L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks
of Linear Technology Corporation. All other trademarks are the property of their respective
owners.
= 25°C
A
= 1.5A, I = 2.5A
OUT1 OUT2
LT8616
MIN TYP MAX
5.8 42
4.1 42
4.88 5.02 5.15
3.21 3.29 3.37
1.85 2.05 2.25
1.5
2.5
85.1
UNITS
V
V
V
V
MHz
A
A
%
dc2169af
1