MIC45208 Datasheet, PDF (3/31 Pages) Micrel Semiconductor – 26V 10A DC-to-DC Power Module

Micrel, Inc.
MIC45208
Pin Description
MIC45208
Pin Number
Pin Name
1, 2
5VDD
3, 4
PVDD
5, 6, 7
PGND
8  11
30  36
12  19
20  29
37, 38
39
40, 41
42, 43, 44
45, 52
SW
PVIN
VOUT
RIA
RIB
ANODE
BST
GND
46
FB
47
PG
48
EN
49
VIN
50
FREQ
51
ILIM
Pin Function
Internal +5V linear regulator output. Powered by VIN, 5VDD is the internal supply bus for the
device. In the applications with VIN<+5.5V, 5VDD should be tied to VIN to bypass the linear
regulator.
PVDD: Supply input for the internal low-side power MOSFET driver.
Power Ground. PGND is the return path for the step-down power module power stage. The
PGND pin connects to the sources of internal low-side power MOSFET, the negative terminals of
input capacitors, and the negative terminals of output capacitors.
The SW pin connects directly to the switch node. Due to the high-speed switching on this pin, the
SW pin should be routed away from sensitive nodes. The SW pin also senses the current by
monitoring the voltage across the low-side MOSFET during OFF time.
Power Input Voltage: Connection to the drain of the internal high side power MOSFET. Connect
an input capacitor from PVIN to PGND.
Power Output Voltage: Connected to the internal inductor, the output capacitor should be
connected from this pin to PGND as close to the module as possible.
Ripple Injection Pin A. Leave floating, no connection.
Ripple Injection Pin B. Connect this pin to FB.
Anode Bootstrap Diode: Anode connection of internal bootstrap diode, this pin should be
connected to the PVDD pin.
Connection to the internal bootstrap circuitry and high side power MOSFET drive circuitry. Leave
floating, no connection.
Analog Ground. Connect bottom feedback resistor to GND. GND and PGND should be
connected together at a low impedance point.
Feedback: Input to the transconductance amplifier of the control loop. The FB pin is referenced to
0.8V. A resistor divider connecting the feedback to the output is used to set the desired output
voltage. Connect the bottom resistor from FB to GND.
Power Good: Open Drain Output. If used, connect to an external pull-up resistor of at least
10kohm between PG and the external bias voltage.
Enable: A logic signal to enable or disable the step-down regulator module operation. The EN pin
is TTL/CMOS compatible. Logic high = enable, logic low = disable or shutdown. Do not leave
floating
Internal 5V linear regulator input. A 1μF ceramic capacitor from VIN to GND is required for
decoupling.
Switching Frequency Adjust: Use a resistor divider from VIN to GND to program the switching
frequency. Connecting FREQ to VIN sets freq=600kHz.
Current Limit: Connect a resistor between ILIM and SW to program the current limit.
May 29, 2014
3
Revision 1.2