Datasheet
LM34910C
4
ON TIMER
280 ns
OFF TIMER
LEVEL
SHIFT
THERMAL
SHUTDOWN
7V SERIES
REGULATOR
V
CC
UVLO
8V-50V
Input
V
IN
C1
R
ON
C5
10
R
ON
/
SD
8
7
SS
6
FB
5
RTN
LOGIC
REGULATION
COMPARATOR
OVER-
VOLTAGE
COMPARATOR
+
-
+
-
+
-
D1
S
GND
I
SEN
3
SW
1
BST
2
V
CC
9
V
IN
COMPLETE
START
R
ON
START
COMPLETE
C3
C4
R1
R2
R3
C2
CURRENT LIMIT
COMPARATOR
R
SENSE
50 m:
V
OUT1
V
OUT2
2.875V
2.5V
11.5 PA
GATE DRIVE
UVLO
L1
+
-
+
-
0.7V
DRIVER
DRIVER
62.5 mV
C6
LM34910C
SNVS517B –MAY 2007–REVISED MARCH 2013
www.ti.com
Typical Application Circuit and Block Diagram
PIN DESCRIPTIONS
Pin Name Description Application Information
Internally connected to the buck switch source. Connect to
1 SW Switching Node
the external inductor, diode, and boost capacitor.
Connect a 0.022 µF capacitor from SW to this pin. An
2 BST Boost pin for boot-strap capacitor
internal diode charges the capacitor during the off-time.
Internally the current sense resistor connects from this pin to
3 I
SEN
Current sense input S
GND
. Re-circulating current flows out of this pin to the free-
wheeling diode. Current limit is set at 1.25A.
Re-circulating current flows into this pin to the current sense
4 S
GND
Sense Ground
resistor.
Ground for all internal circuitry other than the current limit
5 RTN Circuit Ground
detection.
Internally connected to the regulation and over-voltage
6 FB Feedback
comparators. The regulation level is 2.5V.
An internal 11.5 µA current source charges an external
7 SS Softstart
capacitor to 2.5V to provide the softstart function.
An external resistor from V
IN
to this pin sets the buck switch
8 R
ON
/SD On-time Control and Shutdown
on-time. Grounding this pin shuts down the regulator.
Nominally regulated to 7.0V. An external voltage (8V-14V)
9 V
CC
Output from the start-up regulator can be connected to this pin to reduce internal dissipation.
An internal diode connects V
CC
to V
IN
.
10 V
IN
Input supply voltage Nominal input range is 8.0V to 50V.
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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