MIC2128 Datasheet, PDF (14/32 Pages) Microchip Technology – 75V, Synchronous Buck Controller Featuring Adaptive On-Time Control with External Soft Start

MIC2128
3.0 PIN DESCRIPTION
The descriptions of the pins are listed in Table 3-1.
TABLE 3-1:
MIC2128
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
PIN FUNCTION TABLE
Symbol
PG
I_LIM
SW
BST
DH
P_GND
DL
P_VDD
EXTVDD
EN
FREQ
SS
FB
A_GND
V_DD
V_IN
EP
Pin Function
Open-drain Power Good Output pin
Current Limit setting resistor connection pin
Switch Pin and Current Sense Input for negative current limit
Bootstrap Capacitor Connection Pin
High-side N-MOSFET gate driver Output
Power Ground
Low-side N-MOSFET gate driver output.
Internal high voltage LDO Output of the MIC2128
Supply to the internal low voltage LDO
Enable Input
Switching Frequency Programming Input
Soft-Start time setting capacitor connection pin
Feedback Input
Analog ground
Supply for the MIC2128 internal analog circuits
Supply Input for the internal high voltage LDO
Exposed Pad
3.1 Power Good Output Pin (PG)
Connect PG to V_DD through a pull up resistor. PG is low
when the FB voltage is 10% below the 0.6V reference
voltage.
3.2 Current Limit Pin (I_LIM)
Connect a resistor from I_LIM to SW to set current limit.
Refer to Section 4.3 “Current Limit (ILIM)” for more
details.
3.3 Switch Pin (SW)
SW pin provides return path for the high-side
N-MOSFET gate driver when DH is low and is also
used to sense low-side MOSFET current by monitoring
the SW node voltage for negative current limit function.
Connect SW to the pin where high-side MOSFET
source and the low-side MOSFET drain terminal are
connected together.
3.4 Bootstrap Capacitor Pin (BST)
BST capacitor acts as supply for the high-side
N-MOSFET driver. Connect a minimum of 0.1 µF low
ESR ceramic capacitor between BST and SW. Refer to
Section 4.5 “High-Side MOSFET Gate Drive (DH)”
section for more details.
3.5 High-Side N-MOSFET Gate Driver
Output Pin (DH)
High-side N-MOSFET gate driver Output. Connect DH
to the gate of external high-side N-MOSFET.
3.6 Power Ground Pin (P_GND)
P_GND provides return path for the internal low-side
N-MOSFET gate driver output and also acts as
reference for current limit comparator. Connect P_GND to
the external low-side N-MOSFET source terminal and
to the return terminal of P_VDD bypass capacitor.
3.7 Low-Side N-MOSFET Gate Driver
Output Pin (DL)
Low-side N-MOSFET gate driver output. Connect to
the gate terminal of the external low-side N-MOSFET.
DS20005620A-page 14
 2016 Microchip Technology Inc.