Datasheet

Control
Logic
Over
temp
OSC RAMP
INT
SS
VREF
+
-
AVIN
EN
ILIM
SS/TRK
FB
COMP
AGND
PGND
PGOOD
SW
PVIN
PWM
comparator
UVLO
Precision
enable
UVP
SD
Ilimit low
Ilimit high
Zero-cross
Driver
OVP
Powerbad
PWM
0.68V
0.54V
CURRENT
LIMIT
AVIN
AVIN
PVIN
PVIN
OR
OR
OR
+
-
+
-
+
-
+
-
+
-
EA
+
-
+
-
Driver
2.7V
1.35V
0.6V
LM21215
SNVS625E –FEBRUARY 2011–REVISED MARCH 2013 www.ti.com
Block Diagram
Operation Description
GENERAL
The LM21215 switching regulator features all of the functions necessary to implement an efficient low voltage
buck regulator using a minimum number of external components. This easy to use regulator features two
integrated switches and is capable of supplying up to 15A of continuous output current. The regulator utilizes
voltage mode control with trailing edge modulation to optimize stability and transient response over the entire
output voltage range. The device can operate at high switching frequency allowing use of a small inductor while
still achieving high efficiency. The precision internal voltage reference allows the output to be set as low as 0.6V.
Fault protection features include: current limiting, thermal shutdown, over voltage protection, and shutdown
capability. The device is available in the HTSSOP-20 package featuring an exposed pad to aid thermal
dissipation. The LM21215 can be used in numerous applications to efficiently step-down from a 5V or 3.3V bus.
PRECISION ENABLE
The enable (EN) pin allows the output of the device to be enabled or disabled with an external control signal.
This pin is a precision analog input that enables the device when the voltage exceeds 1.35V (typical). The EN pin
has 110 mV of hysteresis and will disable the output when the enable voltage falls below 1.24V (typical). If the
EN pin is not used, it can be left open, and will be pulled high by an internal 2 µA current source. Since the
enable pin has a precise turn-on threshold it can be used along with an external resistor divider network from VIN
to configure the device to turn-on at a precise input voltage.
10 Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated
Product Folder Links: LM21215