DC916A - Demo Manual

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 916
LOW NOISE REGULATED CHARGE PUMP IN 2X2 DFN
LTC3204B-5 and LTC3204B-3.3
DESCRIPTION
Demonstration circuit 916 is a low noise regulated
charge pump in 2X2 DFN. There are two assembly
versions, DC916A-A and DC916A-B for featuring
LTC3204B-5 and LTC3204B-3.3 respectively. The
DC916A-A produces a regulated 5V output from a
2.7V to 5.5V input. The guaranteed output load current is 150mA for VIN between 3.1V and 5.5V, and
65mA for VIN less than 3.1V. The DC916A-B produces
a regulated 3.3V output from a 1.8V to 4.5V input.
The guaranteed output current is 50mA from VIN between 1.9V and 4.5V, and 40mA for VIN less than
1.9V. The circuit requires only three tiny 0603 surface
mount capacitors and consumes minimal board
space. No inductor and diode are needed. The circuit
features constant frequency operation at any load.
Built-in soft-start circuitry prevents excessive inrush
current during start-up. Thermal shutdown and current-limit circuitry allow the parts to survive a continuous output short circuit from VOUT to GND. These
circuits are particularly useful in applications that require low VOUT ripple and extremely small size.
Design files for this circuit board are available. Call
the LTC factory.
, LTC and LT are registered trademarks of Linear Technology Corporation.
PERFORMANCE SUMMARY
PARAMETER
CONDITION
MIN
TYP
MAX
DC916A-A (LTC3204B-5)
2.7V
5.5V
DC916A-B (LTC3204B-3.3)
1.8V
4.5V
Input Voltage Range
DC916A-A (LTC3204B-5)
Output Voltage VOUT
3.1V< VIN <5.5V, IOUT<150mA
4.8V
5V
5.2V
3.168V
3.3V
3.432V
VIN = 3.6V, IOUT = 150mA (DC916A-A)
20mVP–P
50mVP–P
VIN = 2.4V, IOUT = 50mA (DC916A-B)
10mVP–P
20mVP–P
2.7V< VIN <5.5V, IOUT<65mA
DC916A-B (LTC3204B-3.3)
1.9V< VIN <4.5V, IOUT<50mA
1.8V< VIN <4.5V, IOUT<40mA
Output Ripple VOUT
Nominal Switching Frequency
Efficiency
1.2MHz
VIN = 3.0V, IOUT = 100mA (DC916A-A)
81.2%
VIN = 1.8V, IOUT = 20mA (DC916A-B)
90.2%
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QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 916
LOW NOISE REGULATED CHARGE PUMP IN 2X2 DFN
QUICK START PROCEDURE
3.
Connect the load between VOUT and GND terminals.
4.
Turn on the power at the input.
NOTE: Make
sure that the input voltage does not exceed 5.5V for DC916A-A or 4.5V for DC916A-B. To
prevent input voltage overshoot when the circuit is
connected to a live supply, an aluminum electrolytic capacitor can be added to bypass the VIN at
the input terminals. See Linear Technology Application Note 88 for a complete discussion.
Demonstration circuit 916 is easy to set up to evaluate the performance of the LTC3204B-5 and
LTC3204B-3.3. Refer to Figure 1 for proper measurement equipment setup and follow the procedure
below:
NOTE: When
measuring the input or output voltage
ripple, care must be taken to avoid a long ground lead
on the oscilloscope probe. Measure the input or output voltage ripple by touching the probe tip directly
across the VIN or VOUT and GND terminals. See
Figure 2 for proper scope probe technique.
1.
ON
6.
With power off, connect the input power supply to
VIN and GND terminals.
Check for the proper output voltages. VOUT = 4.8V
to 5.2V for DC916A-A, VOUT = 3.168V to 3.432V for
DC916A-B
NOTE: If there is no output, temporarily disconnect
the load to make sure that the load is not set too
high.
Place jumpers in the following positions:
JP1
2.
5.
Once the proper output voltages are established,
adjust the loads within the operating range and observe the output voltage regulation, ripple voltage,
efficiency and other parameters.
Figure 1. Proper Measurement Equipment Setup
GND
VIN
Figure 2. Measuring Input or Output Ripple
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QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 916
LOW NOISE REGULATED CHARGE PUMP IN 2X2 DFN
OPERATING PRINCIPLES
The LTC3204B-5/LTC3204B-3.3 use switched capacitor charge pump to boost VIN to a regulated voltage.
Regulation is achieved by sensing the output voltage
through an internal resistor divider and by modulating
the charge pump output current based on the error
signal. A 2-phase non-overlapping clock activates the
charge pump switches. The flying capacitor is
charged from VIN on the first phase of the clock. On
the second phase of the clock, it is stacked in series
with VIN and connected to VOUT. This sequence of
charging and discharging the flying capacitor continues at a free running frequency of 1.2MHz.
The LTC3204B datasheet gives complete description
of the part, operation and application information. The
datasheet must be read in conjunction with this quick
start guide for demo circuit 916.
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QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 916
LOW NOISE REGULATED CHARGE PUMP IN 2X2 DFN
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