MIC2179

Features:

• 4.5V to 16.5V input voltage range
• Dual-mode operation for high efficiency (up to 96%)
PWM mode for > 150mA load current
Skip mode for <150mA load current
• 150mW internal power MOSFETs at 12V input
• 200kHz preset switching frequency
• Low quiescent current
1.0mA in PWM mode
600mA in skip mode
< 5A in shutdown mode
• Current-mode control
Simplified loop compensation
Superior line regulation
• 100% duty cycle for low dropout operation
• Current limit
• Thermal shutdown
• Undervoltage lockout




Application

• High-efficiency, battery-powered supplies
• Buck (step-down) dc-to-dc converters
• Cellular telephones
• Laptop computers
• Hand-held instruments
• Battery Charger




Pinout






Specifications

Supply Voltage [100ms transient] (V_IN) ..................... 18V
Output Switch Voltage (V_SW) ..................................... 18V
Output Switch Current (I_SW) ..................................... 6.0A
Enable, PWM Control Voltage (V_EN, V_PWM) .................18V
Sync Voltage (V_SYNC) ....................................................6V




Description

The Micrel MIC2179 is a 200kHz synchronous buck (stepdown) switching regulator designed for high-efficiency, battery- powered applications.

The MIC2179 operates from a 4.5V to 16.5V input and features internal power MOSFETs that can supply up to 1.5A
output current. MIC2179 can operate with a maximum duty cycle of 100% for use in low-dropout conditions. It also features a shutdown mode that reduces quiescent current to less than 5mA.

The MIC2179 achieves high efficiency over a wide output current range by operating in either PWM or skip mode. The operating mode of MIC2179 is externally selected, typically by an intelligent system, which chooses the appropriate mode according to operating conditions, efficiency, and noise requirements. The switching frequency is preset to 200kHz and can be synchronized to an external clock signal of up to 300kHz.

The MIC2179 uses current-mode control with internal current sensing. Current-mode control provides superior line regulation and makes the regulator control loop easy to compensate. The output of MIC2179 is protected with pulse-by-pulse current limiting and thermal shutdown. Undervoltage lockout turns the output off when the input voltage is less than 4.5V.

The MIC2179 and is packaged in a 20-lead SSOP package with an operating temperature range of 40°C to +85°C.