DEMO MANUAL DC2359A
LTC3624
High Efficiency Synchronous
Step-Down Regulator with
Description
Demonstration circuit 2359A is a synchronous step-down
®
regulator using LT C
The DC2359A operates from an input voltage range of 2.7V
to 17V and provides and adjustable output voltage range
from 1.2V to 5V (V
current. A user-selectable mode input is provided with
the following options: Burst Mode
the highest efficiency at light loads, while Pulse-Skipping
mode (PS) provides the lowest output voltage ripples.
Forced Continuous mode (FC) is also available for low
EMI and noise interference.
The MODE/SYNC pin can also be used to synchronize
the switching frequency to an external clock signal. The
switching frequency is fixed at 1MHz with a ±40% sync
capture range.
The regulator features ultralow quiescent current and high
efficiencies over a wide V
3624HMSE monolithic buck regulator.
< VIN) at 2A of continuous output
OUT
®
operation provides
and V
IN
range. DC2359A
OUT
Ultralow Quiescent Current
uses very low profile surface mount components and all
ceramic output capacitor solutions. The compact 12-lead
MSE (5mm × 4mm × 1mm) thermally enhanced package
makes LTC3624HMSE an excellent choice for battery
powered equipment, emergency radio and general pur
pose step
specified over an
of –40°C to 150°C, typically required for automotive, in
dustrial and military applications that are subject to high
ambient temperatures.
It is recommended to read the data sheet and demo manual
of LTC3624 prior using or making any changes to DC2359A.
Design files for this circuit board are available at
http://www.
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.
-down power supplies. The H-Grade version is
operating junction temperature range
linear.com/demo/DC2359A
-
-
performance summary
PARAMETER CONDITIONS VALUE
Input Voltage Range 2.7V to 17V
On Board User Selectable Output Voltages V
Default Mode Setting JP2 Burst Mode (“BM” on Circuit Board)
Fixed Switching Frequency Internally Programmed Frequency 1MHz ±20%
Default Output Voltage V
Maximum Continuous Output Current I
Output Voltage Ripples (Peak to Peak) V
Load Transient Response V
Thermal Performance V
Efficiency V
OUT
OUT
Specifications are at TA = 25°C
= 2.7V to 17V, I
IN
(V
< VIN)
OUT
VIN = 12V, V
= 12V, V
IN
= 12V, V
IN
C
OUT
= 12V, V
IN
f
SW
= 12V, V
IN
f
SW
OUT
OUT
OUT
= 1 × 47µF
OUT
= 1MHz, TA = 25°C
OUT
= 1MHz, TA = 25°C
OUT
= 5V, I
= 5V, I
= 5V, I
= 5V, I
= 5V, I
= 2A
= 0A to 2A 5V ±2%
OUT
= 2A 8.8mV (Figure 7)
OUT
= 1A to 2A,
OUT_STEP
= 2A,
OUT
= 2A, BM,
OUT
1.2V, 1.8V, 2.5V, 3.3V and 5V
2A
219mV (Figure 8)
Figure 9
89.7% (Figure 3)
dc2359afb
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DEMO MANUAL DC2359A
Quick start proceDure
Demonstration circuit 2359A is easy to set up to evaluate
the performance of the LTC3624HMSE. Please refer to
Figure 1 for proper measurement equipment setup and
follow the procedure below:
1. Place jumpers in the following positions for a typical
5V output application:
Table 1. Typical 5V Output Voltage Jumper Selection
JP1 JP2 JP7
RUN MODE/SYNC V
ON BM 5.0V
OUT
2. With power off, connect the input power supply at
(E1) and GND (E2)
V
IN
3. Connect the Load between V
(E8) and GND (E9).
OUT
Preset the load to 0A.
4. Connect the DMMs to the input and output to monitor
the input voltage and output voltage.
5. Turn on the power supply at the input. The RUN pin
jumper should be at “ON” position. Measure and make
sure the input supply voltage is 12V. The output voltage
should be 5V ±2%.
7. To select other output voltages, use the on board user
selectable output voltage jumpers. Shutting down
LTC3624HMSE by placing RUN pin jumper (JP1) to the
OFF position or turn off the input power supply. Refer
to the following table (Table 2) for the output voltage
selection and repeat step 2 to 6.
Table 2. Output Voltage Jumper Selection
JP3 JP4 JP5 JP6 JP7 JP8*
1.2V 1.8V 2.5V 3.3V 5V User Select
*If JP8 is selected, R6 needs to be calculated and inserted to obtain the
desired output voltage.
NOTE 1: To measure the input/output voltage ripple properly, do not use the long ground lead on the oscilloscope
probe. See Figure
2 for the proper scope probe technique.
Short, stiff leads need to be soldered to the (+) and (–)
terminals of an output capacitor. The probe’s ground ring
needs to touch the (–) lead and the probe tip needs to
touch the (+) lead.
NOTE 2: The DC2359A can also be used to evaluate the
LTC3624HMSE-2 (2.25MHz) by simply replacing U1 with
the LTC3624HMSE-2 and changing inductor L1 to 1.5µH
(Coilcraft XAL4020-152ME).
6. Once the input and output voltages are properly es
tablished, adjust the loads within the operating range
(0Ato 2A Max) and observe the output voltage regulation, output
other parameters. Refer
voltage ripple, switch node waveform and
to Figure 2 for proper output
voltage ripple measurement.
-
dc2359afb
2
Quick start proceDure
DEMO MANUAL DC2359A
Figure 1. Proper Measurement Equipment Setup
+ –
Figure 2. Scope Probe Placement for Measuring Output Voltage Ripple
C
OUT
V
OUT
GND
dc2359afb
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