LM34917A Datasheet, PDF (4/16 Pages) National Semiconductor (TI) – Ultra Small 33V, 1.25A Constant On-Time Buck Switching Regulator with Intelligent Current Limit

Symbol
Parameter
Conditions
On Timer
t_ON - 1
t_ON - 2
t_ON - 3
On-time (normal operation)
On-time (normal operation)
On-time (current limit)
Shutdown threshold at RON/
SD
V_IN = 10V, R_ON = 200 kΩ
V_IN = 32V, R_ON = 200 kΩ
V_IN = 10V, R_ON = 200 kΩ
Voltage at RON/SD rising
Shutdown Threshold
hysteresis
Voltage at RON/SD falling
Off Timer
t_OFF
Minimum Off-time
Regulation and Over-Voltage Comparators (FB Pin)
V_REF
FB regulation threshold
FB over-voltage threshold
SS pin = steady state
FB bias current
FB = 3V
Input Over-Voltage Shutdown
V_IN(OV)
Shutdown voltage threshold at V_IN increasing
VIN
Thermal Shutdown
T_SD
Thermal shutdown temperature Junction temperature rising
Thermal shutdown hysteresis
Thermal Resistance
θ_JA
Junction to Ambient
0 LFPM Air Flow
Min
2.1
0.3
2.445
33.0
Typ
2.8
860
1.13
0.65
40
90
2.50
2.9
10
34.8
175
20
58
Max
3.5
1.0
2.550
36.9
Units
µs
ns
µs
V
mV
ns
V
V
nA
V
°C
°C
°C/W
Note 1: Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Ratings are conditions under which operation of the
device is intended to be functional. For guaranteed specifications and test conditions, see the Electrical Characteristics.
Note 2: The human body model is a 100pF capacitor discharged through a 1.5kΩ resistor into each pin.
Note 3: V_CC provides self bias for the internal gate drive and control circuits. Device thermal limitations limit external loading
Note 4: For detailed information on soldering micro SMD packages, refer to AN-1112 available from National Semiconductor Corporation.
Note 5: Typical specifications represent the most likely parametric norm at 25°C operation.
www.national.com
4