MIC2182 Datasheet, PDF (3/28 Pages) Micrel Semiconductor – High-Efficiency Synchronous Buck Controller Final Information

MIC2182
Micrel
Pin Description
Pin Number
1
2
3
4
5
6
7 (fixed)
7 (adj)
8
9
10
11
12
13
14
15
16
Pin Name
SS
PWM
COMP
SGND
SYNC
EN/UVLO
VREF
FB
CSH
VOUT
VIN
VDD
PGND
LSD
BST
VSW
HSD
Pin Function
Soft-Start (External Component): Connect external capacitor to ground to
reduce inrush current by delaying and slowing the output voltage rise time.
Rise time is controlled by an internal 5µA current source that charges an
external capacitor to V_DD.
PWM/Skip-Mode Select (Input): Low sets PWM-mode operation. 1nF
capacitor to ground sets automatic PWM/skip-mode selection.
Compensation (Output): Internal error amplifier output. Connect to capacitor
or series RC network to compensate the regulator control loop.
Small Signal Ground (Return): Route separately from other ground traces to
the (–) terminal of C_OUT.
Frequency Synchronization (Input): Optional. Connect to external clock
signal to synchronize the oscillator. Leading edge of signal above the
threshold terminates the switching cycle. Connect to SGND if unused.
Enable/Undervoltage Lockout (Input): Low-level signal powers down the
controller. Input below the 2.5V threshold disables switching and functions
as an accurate undervoltage lockout (UVLO). Input below the threshold
forces complete micropower (< 0.1µA) shutdown.
Reference Voltage (Output): 1.245V output. Requires 0.1µf capacitor to
ground.
Feedback (Input): Regulates FB pin to 1.245V. See “Application Information”
for resistor divider calculations.
Current-Sense High (Input): Current-limit comparator noninverting input. A
built-in offset of 100mV between CSH and V_OUT pins in conjunction with the
current-sense resistor set the current-limit threshold level. This is also the
positive input to the current sense amplifier.
Current-Sense Low (Input): Output voltage feedback input and inverting
input for the current limit comparator and the current sense amplifier.
[Battery] Unregulated Input (Input): +4.5V to +32V supply input.
5V Internal Linear-Regulator (Output): V_DD is the external MOSFET gate
drive supply voltage and an internal supply bus for the IC. Bypass to SGND
with 4.7µF. V_DD can supply up to 5mA for external loads.
MOSFET Driver Power Ground (Return): Connects to source of synchro-
nous MOSFET and the (–) terminal of C_IN
Low-Side Drive (Output): High-current driver output for external synchronous
MOSFET. Voltage swing is between ground and V_DD.
Boost (Input): Provides drive voltage for the high-side MOSFET driver. The
drive voltage is higher than the input voltage by V_DD minus a diode drop.
Switch (Return): High side MOSFET driver return.
High-Side Drive (Output): High-current driver output for high-side MOSFET.
This node voltage swing is between ground and V_IN + 5V – V_{diode drop}.
June 2000
3
MIC2182