Features: ` 16 A typical quiescent current
` 350 mA maximum load capability
` 3 MHz PWM fixed switching frequency (typ)
` Automatic PFM/PWM mode switching
` Available in 5-bump micro SMD package and UR package
` Internal synchronous rectification for high efficiency
` Internal soft start
` 0.01 A typical shutdown current
` Operates from a single Li-Ion cell battery
` Current overload and Thermal shutdown protection
` Three external components required for typical applications
` Low profile solution (0.55mm max height, includes four external components)Application· Mobile phones
· PDAs
· MP3 players
· W-LAN
· Portable Instruments
· Digital still cameras
· Portable Hard disk drivesSpecificationsIf Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications.
If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/Distributors
for availability and specifications.
VIN Pin: Voltage to GND −0.2V to 6.0V
FB, SW, EN Pin: (GND−0.2V) to
(VIN + 0.2V)
Continuous Power Dissipation
(Note 3)
Internally Limited
Junction Temperature (TJ-MAX) +125
Storage Temperature Range −65 to +150
Maximum Lead Temperature
(Soldering, 10 sec.)
260
ESD Rating (Note 4)
Human Body Model: All Pins 2.0 kV
Machine Model: All Pins 200V
DescriptionThe LM3679 step-down DC-DC converter is optimized for powering ultra-low voltage circuits from a single Li-Ion cell battery and input voltage rails from 2.5V to 5.5V. It provides up to 350mA load current, over the entire input voltage range.
The LM3679 output voltage can be configured to 1.2V, 1.5V, or 1.8V.
The device offers superior features and performance for mobile phones and similar portable applications with complex power management systems. Automatic intelligent switching between PWM low-noise and PFM low-current mode offers improved system control. During PWM mode operation, the device operates at a fixed-frequency of 3 MHz (typ). PWM mode drives loads from ~ 80mA to 350mA max. Hysteretic PFM mode extends the battery life by reducing the quiescent current to 16 A (typ) during light load and standby operation.
Internal synchronous rectification provides high efficiency. In shutdown mode (Enable pin pulled low), the device turns off and reduces battery consumption to 0.01 A (typ).
The LM3679 is available in a lead-free (No PB) 5-bump micro SMD package, 0.6mm height, and in an ultra thin 0.3mm height UR package. Using the UR package along with specific external components, allows for a low profile solution size with a max height of 0.55mm. A switching frequency of 3 MHz (typ) allows use of tiny surface-mount components. Only three external surface-mount components, an inductor and two ceramic capacitors, are required. .
LM3679 Data Sheet
