ADP2121-2.3-EVALZ Analog Devices, ADP2121-2.3-EVALZ Datasheet - Page 16

• Manufacturer Part Number: ADP2121-2.3-EVALZ
• Description: Power Management IC Development Tools 6MHz Volt Mode Buck 500mA Bumped Die
• Manufacturer: Analog Devices
• Type: DC/DC Converters, Regulators & Controllersr
• Series: ADP2121r

Specifications of ADP2121-2.3-EVALZ

• Rohs: yes
• Tool Is For Evaluation Of: ADP2121
• Input Voltage: 2.3 V to 5.5 V
• Output Current: 500 mA
• Factory Pack Quantity: 1

ADP2121
delays in the current-limit comparator allow a slight increase and
variation in this specification.
Soft Start
To prevent excessive input inrush current at startup, the ADP2121
operates with an internal soft start. When EN goes high, or when
the part recovers from a fault (UVLO, TSD, or short-circuit
protection), a soft start timer begins. The soft start timer cor-
responds to the maximum soft start period for the given fixed
output voltage. During this time, the peak current limit is gradually
increased to its maximum. As seen in Figure 40 through Figure 45,
the output voltage passes through several stages to ensure that the
converter is able to start up effectively and in proper sequence.
After the soft start period has expired, the peak current limit
remains at 1 A (typical), and the part enters the operating mode
determined by the MODE pin.
Synchronous Rectification
In addition to the P-channel MOSFET switch, the ADP2121
includes an N-channel MOSFET switch to build the synchronous
rectifier. The synchronous rectifier improves efficiency, especially
for small load currents, and reduces cost and board space by
eliminating the need for an external rectifier.
Compensation
The control loop is internally compensated to deliver maxi-
mum performance with no additional external components.
The ADP2121 is designed to work with 0.47 μH chip inductors
and 4.7 μF capacitors (see Table 6, Table 7, and Table 8.) Other
values may reduce performance and/or stability.
Undervoltage Lockout (UVLO)
If the input voltage is below the UVLO threshold, the ADP2121
automatically turns off the power switches and places the part
into a low power consumption mode. This prevents potentially
erratic operation at low input voltages. The UVLO levels have
approximately 100 mV of hysteresis to ensure glitch-free startup.
Rev. B | Page 16 of 20
Output Short-Circuit Protection
If the output voltage is inadvertently shorted to GND, a standard
dc-to-dc controller delivers maximum power into that short.
This may result in a potentially catastrophic failure. To prevent
this, the ADP2121 senses when the output voltage is below the
short-circuit protection threshold (typically 1.24 V).
At this point, the controller turns off for approximately 1.8 ms
(V
(V
sequence. This cycle repeats until the short is removed or the
part is disabled. This dramatically reduces the power delivered
into the short circuit, yet still allows the converter to recover if
the fault is removed.
Thermal Shutdown (TSD) Protection
The ADP2121 also includes TSD protection. If the die
temperature exceeds 150°C (typical), the TSD protection
activates and turns off the power devices. They remain off
until the die temperature falls below 135°C (typical), at
which point the converter restarts.
OUT
OUT
= 1.82 V), 0.44 ms (V
= 2.3 V), and then automatically initiates a soft start
Figure 55. Output Short-Circuit Protection, V
INDUCTOR CURRENT (500mA/DIV)
OUTPUT VOLTAGE (200mV/DIV)
TIME (1ms/DIV)
OUT
= 1.8 V and 1.85 V), or 0.48 ms
OUT
= 1.82 V