Datasheet

LM34919B
LM34919B-Q1
SNVS623A –MAY 2010–REVISED FEBRUARY 2013 www.ti.com
Electrical Characteristics
Specifications with standard type are for T
J
= 25°C only; limits in boldface type apply over the full Operating Junction
Temperature (T
J
) range. Minimum and Maximum limits are specified through test, design, or statistical correlation. Typical
values represent the most likely parametric norm at T
J
= 25°C, and are provided for reference purposes only. Unless
otherwise stated the following conditions apply: V
IN
= 12V, R
ON
= 20kΩ. See
(1)
.
Symbol Parameter Conditions Min Typ Max Units
Start-Up Regulator, V
CC
V
CC
Reg V
CC
regulated output V
IN
= 12V 6.6 7 7.4
V
V
IN
=6V, I
CC
= 3 mA, 5.3 5.91
V
IN
-V
CC
dropout voltage I
CC
= 0 mA, non-switching 20 mV
V
CC
= UVLO
VCC
+ 250 mV
V
CC
Output Impedance 0 mA ≤ I
CC
≤ 5 mA, V
IN
= 6V 24
Ω
0 mA ≤ I
CC
≤ 5 mA, V
IN
= 8V 12
V
CC
current limit
(2)
V
CC
= 0V 15 mA
UVLO
VCC
V
CC
under-voltage lockout threshold V
CC
increasing 5.25 V
measured at V
CC
V
CC
decreasing 5.1 5.25 V
UVLO
VCC
hysteresis, at V
CC
150 mV
V
CC
under-voltage lock-out threshold V
IN
increasing, I
CC
= 3 mA 5.25 5.6 V
measured at V
IN
V
IN
decreasing, I
CC
= 3 mA 5.1 5.4 V
UVLO
VCC
filter delay 100 mV overdrive 3 µs
I
Q
I
IN
operating current Non-switching, FB = 3V, SW = Open 0.78 1.0 mA
I
SD
I
IN
shutdown current RON/SD = 0V, SW = Open 215 330 µA
Switch Characteristics
Rds(on) Buck Switch Rds(on) I
TEST
= 200 mA 0.5 1.0 Ω
UVLO
GD
Gate Drive UVLO V
BST
- V
SW
Increasing 2.65 3.6 4.40
V
V
BST
- V
SW
Decreasing 3.2
UVLO
GD
hysteresis 400 mV
Softstart Pin
V
SS
Pull-up voltage 2.5 V
Internal current source V
SS
= 1V 10.5 µA
Current Limit
I
LIM
Threshold Current out of ISEN 0.52 0.64 0.76 A
Resistance from ISEN to SGND 135 mΩ
Response time 50 ns
On Timer
t
ON
- 1 On-time V
IN
= 12V, R
ON
= 20kΩ 127 170 213 ns
t
ON
- 2 On-time V
IN
= 24V, R
ON
= 20 kΩ 110 ns
t
ON
- 3 On-time V
IN
= 6V, R
ON
= 20 kΩ 335 ns
Shutdown threshold Voltage at RON/SD rising 0.4 0.74 1.2 V
Threshold hysteresis Voltage at RON/SD 40 mV
Off Timer
t
OFF
Minimum Off-time V
IN
= 6V, I
CC
= 3mA 60 88 120
ns
V
IN
= 8V, I
CC
= 3mA 58 82 118
Regulation and Over-Voltage Comparators (FB Pin)
V
REF
FB regulation threshold SS pin = steady state 2.440 2.5 2.550 V
FB over-voltage threshold 2.9 V
FB bias current FB = 3V 1 nA
(1) Typical specifications represent the most likely parametric norm at 25°C operation.
(2) V
CC
provides self bias for the internal gate drive and control circuits. Device thermal limitations limit external loading
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