LM34919_14 Datasheet, PDF (4/21 Pages) Texas Instruments – Ultra-Small 40-V 600-mA Constant On-Time Buck Switching Regulator

LM34919
SNOSAY2D – MAY 2007 – REVISED JUNE 2008
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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 = 200kΩ. See ⁽¹⁾.
Symbol
Parameter
Test Conditions
Min Typ Max Unit
Start-Up Regulator, V_CC
V_CCReg V_CC regulated output
V_IN-V_CC dropout voltage
V_CC output impedance
V_CC current limit⁽²⁾
UVLO_VCC V_CC under-voltage lockout threshold
UVLO_VCC hysteresis
UVLO_VCC filter delay
I_Q
I_IN operating current
I_SD
I_IN shutdown current
Switch Characteristics
I_CC = 0 mA,
V_CC = UVLO_VCC + 250 mV
0 mA ≤ I_CC ≤ 5 mA, V_IN = 8V
V_CC = 0V
V_CC increasing
V_CC decreasing
100 mV overdrive
Non-switching, FB = 3V, SW = Open
RON/SD = 0V, SW = Open
6.6
7
7.4
V
1.2
V
175
Ω
9.5
mA
5.7
V
150
mV
3
µs
0.5
0.8
mA
75
150
µA
Rds(on) Buck Switch Rds(on)
UVLO_GD Gate Drive UVLO
UVLO_GD hysteresis
Softstart Pin
I_TEST = 200 mA
V_BST - V_SW Increasing
0.5
1.0
Ω
3.0
4.4
5.2
V
480
mV
V_SS
Pull-up voltage
Internal current source
Current Limit
V_SS = 1V
2.5
V
10.5
µA
I_LIM
Threshold
Resistance from ISEN to SGND
Current out of ISEN
0.52 0.64 0.76
A
140
mΩ
Response time
150
ns
On Timer
t_ON - 1
t_ON - 2
On-time
On-time
Shutdown threshold
V_IN = 10V, R_ON = 200 kΩ
V_IN = 40V, R_ON = 200 kΩ
Voltage at RON/SD rising
2.1 2.77 3.5
µs
700
ns
0.45 0.8
1.2
V
Threshold hysteresis
Voltage at RON/SD
25
mV
Off Timer
t_OFF
Minimum Off-time
Regulation and Over-Voltage Comparators (FB Pin)
155
ns
V_REF
FB regulation threshold
FB over-voltage threshold
SS pin = steady state
2.440 2.5 2.550 V
2.9
V
FB bias current
FB = 3V
1
nA
Thermal Shutdown
T_SD
Thermal shutdown temperature
Thermal shutdown hysteresis
175
°C
20
°C
Thermal Resistance
θ_JA
Junction to Ambient
0 LFPM Air Flow
61
°C/W
(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
4
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