Datasheet

LM3100
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
11
12
SW
SW
N/C
VIN
VIN
BST
GND
SS
N/C
N/C
N/C
N/C
PGND
PGND
VCC
RON
EN
FB
N/C
TST
EP
LM3100
SNVS421G –JANUARY 2006–REVISED APRIL 2013 www.ti.com
Connection Diagram
Figure 1. 20-lead Plastic
HTSSOP (PWP0020A)
PIN DESCRIPTIONS
Pin Name Description Application Information
1,9,10,12,19,20 N/C No Connection These pins must be left unconnected.
2, 3 SW Switching Node Internally connected to the buck switch source. Connect to
output inductor.
4, 5 VIN Input supply voltage Supply pin to the device. Nominal input range is 4.5V to
36V.
6 BST Connection for bootstrap capacitor Connect a 0.033µF capacitor from SW pin to this pin. An
internal diode charges the capacitor during the high-side
switch off-time.
7 GND Analog Ground Ground for all internal circuitry other than the synchronous
switches.
8 SS Soft-start An internal 8µA current source charges an external
capacitor to provide the soft- start function.
11 TST Test mode enable pin Force the device into test mode. Must be connected to
ground for normal operation.
13 FB Feedback Internally connected to the regulation and over-voltage
comparators. The regulation setting is 0.8V at this pin.
Connect to feedback divider.
14 EN Enable pin Connect a voltage higher than 1.26V to enable the
regulator.
15 RON On-time Control An external resistor from VIN to this pin sets the high-side
switch on-time.
16 VCC Start-up regulator Output Nominally regulated to 6V. Connect a capacitor of not less
than 680nF between VCC and GND for stable operation.
17, 18 PGND Power Ground Synchronous rectifier MOSFET source connection. Tie to
power ground plane.
DAP EP Exposed Pad Thermal connection pad, connect to GND.
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
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