MIC2178

Features:

• 4.5V to 16.5V input voltage range
• Dual-mode operation for high efficiency (up to 96%)
PWM mode for > 200mA load current
Skip mode for < 200mA load current
• 100mW internal power MOSFETs at 12V input
• 200kHz preset switching frequency
• Low quiescent current
1.0mA in PWM mode
600mA in skip mode
< 5mA 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
• Palmtop computers
• Laptop computers
• Cellular telephones
• Hand-held instruments
• Battery Chargers




Pinout






Specifications

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




Description

The Micrel MIC2178 is a 200kHz synchronous buck (stepdown) switching regulator designed for high-efficiency, battery- powered applications.

The MIC2178 operates from a 4.5V to 16.5V input and features internal power MOSFETs that can supply up to 2.5A output current. It can operate with a maximum duty cycle of 100% for use in low-dropout conditions. MIC2178 also features a shutdown mode that reduces quiescent current to less than 5A.

The MIC2178 achieves high efficiency over a wide output current range by operating in either PWM or skip mode. The operating mode 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, MIC2178 can be synchronized to an external clock signal of up to 300kHz.

The MIC2178 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 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 MIC2178 and is packaged in a 20-lead wide power SOIC package with an operating temperature range of 40°C to +85°C.