1 Features
• Designed for rugged industrial applications:
– Junction temperature range –40°C to +150°C
– Input transient protection up to 70 V
– Wide input voltage range: 3.0 V (falling
threshold) to 65 V
– Low EMI and minimized switch node ringing
– Adjustable, 5-V fixed output voltage options
available
• Suited for scalable industrial power supplies:
– Pin compatible with LMR36506 (65 V, 600 mA)
– Adjustable switching frequency: 200 kHz to 2.2
MHz with RT pin variant
• Minimized solution size and cost:
– Highest power density with internal
compensation and reduced external component
count
– Ultra-small, 2-mm × 2-mm HotRod™ package
with wettable flanks available
• High efficiency across load range with low power
dissipation:
– > 90% peak efficiency at 1 MHz (5 VOUT
adjustable)
• Ultra-low operating quiescent current at no load
– 4 μA at 24 VIN to 3.3 VOUT (fixed output option)

2 Applications
• Factory automation: field transmitters and process
sensors
• Building automation: HVAC and fire safety
• Appliances: garden and power tools

3 Description
The LMR36503 is the industry smallest 65 V, 0.3
A synchronous step-down DC/DC converter in 2-
mm × 2-mm HotRod package. This easy-to-use
converter can handle input voltage transients up to
70 V, provide excellent EMI performance and support
fixed 5 V and other adjustable output voltages. The
transient tolerance reduces the necessary design
effort to protect against input overvoltage and meets
the surge immunity requirements of IEC 61000-4-5.
The LMR36503 uses the peak current mode control
architecture with internal compensation to maintain
stable operation with minimal output capacitance. The
LMR36503 with the right resistor selection from the
RT pin to ground can be externally programmed
to any desired switching frequency of operation
over a wide range from 200 kHz to 2.2 MHz. The
precision EN/UVLO feature allows precise control of
the device during the start-up and shutdown. The
power-good flag, with built-in glitch filter and delayed
release, offers a true indication of the system status,
eliminating the requirement for an external supervisor.
The compact solution size and rich feature set of
LMR36503 simplifies implementation for a wide range
of industrial applications.