LM34927SD Datasheet, PDF (4/26 Pages) Texas Instruments – LM34927 Integrated Secondary Side Bias Regulator for Isolated DC-DC Converters

LM34927
SNVS799F – APRIL 2012 – REVISED DECEMBER 2013
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Electrical Characteristics
Specifications with standard typeface are for T_J = 25°C, and those with boldface type apply over full Operating Junction
Temperature range. V_IN = 48 V, unless otherwise stated. See ⁽¹⁾.
Symbol
Parameter
Conditions
Min
Typ
Max
Unit
V_CC Supply
V_CC Reg V_CC Regulator Output
V_CC Current Limit
V_CC UVLO Threshold (V_CC
increasing)
V_IN = 48 V, I_CC = 20 mA
V_IN = 48 V ⁽²⁾
6.25
7.6
8.55
V
26
mA
4.15
4.5
4.9
V
V_CC UVLO Hysteresis
V_CC Drop Out Voltage
I_IN Operating Current
I_IN Shutdown Current
Under-Voltage Sensing Function
V_IN = 8 V, I_CC = 20 mA
Non-Switching, FB = 3 V
UVLO = 0 V
300
mV
2.3
V
1.75
mA
50
225
µA
UV Threshold
UV Rising
1.19
1.225
1.26
V
UV Hysteresis Input Current
UV = 2.5 V
-10
-20
-29
µA
Remote Shutdown Threshold
Voltage at UVLO Falling
0.32
0.66
V
Remote Shutdown Hysteresis
110
mV
Regulation and Over-Voltage Comparators
FB Regulation Level
Internal Reference Trip Point for
Switch ON
1.2
1.225
1.25
V
FB Overvoltage Threshold
Trip Point for Switch OFF
1.62
V
FB Bias Current
60
nA
Switch Characteristics
Buck Switch R_DS(ON)
Synchronous R_DS(ON)
Gate Drive UVLO
Gate Drive UVLO Hysteresis
I_TEST = 200 mA, BST-SW = 7 V
I_TEST = 200 mA
V_BST − V_SW Rising
0.8
1.8
Ω
0.45
1
Ω
2.4
3
3.6
V
260
mV
Minimum Off-Time
Minimum Off-Timer
FB = 0 V
144
ns
On Time Generator
T_ON Test 1
T_ON Test 2
T_ON Test 3
T_ON Test 4
Current Limit
V_IN = 32 V, R_ON = 100 k
V_IN = 48 V, R_ON = 100 k
V_IN = 75 V, R_ON = 250 k
V_IN = 10 V, R_ON = 250 k
270
350
460
ns
188
250
336
ns
250
370
500
ns
1880
3200
4425
ns
Current Limit Threshold
0.7
1.02
1.3
A
Current Limit Response Time
Time to Switch Off
150
ns
OFF-Time Generator (Test 1)
OFF-Time Generator (Test 2)
Thermal Shutdown
FB = 0.1 V, V_IN = 48 V
FB = 1.0 V, V_IN = 48 V
12
µs
2.5
µs
Tsd
Thermal Shutdown Temperature
165
°C
Thermal Shutdown Hysteresis
20
°C
Thermal Resistance
Junction to Ambient
θ_JA
SO PowerPAD-8
WSON-8
40
°C/W
40
°C/W
(1) All limits are specified by design. All electrical characteristics having room temperature limits are tested during production at T_A = 25°C.
All hot and cold limits are specified by correlating the electrical characteristics to process and temperature variations and applying
statistical process control.
(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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