Datasheet

LM5021
SNVS359D –MAY 2005–REVISED MARCH 2013 www.ti.com
Electrical Characteristics
(1)
(continued)
Specifications in standard type face are for T
J
= +25°C and those in boldface type apply over the full Operating Junction
Temperature Range. Unless otherwise specified: V
IN
= 15V, R
T
= 44.2KΩ.
Symbol Parameter Conditions Min Typ Max Unit
SOFT-START
V
SS-OCV
SS pin open-circuit voltage 4.3 5.2 6.1 V
Soft-start Current Source 15 22 30 µA
Soft-start to COMP Offset 0.35 0.55 0.75 V
COMP sinking impedance During SS ramp 60 Ω
OSCILLATOR
Frequency1 (RT = 44.2K) 135 150 165 kHz
Frequency2 (RT = 13.3K) 440 500 560 kHz
Sync threshold 2.4 3.2 3.8 V
PWM COMPARATOR
COMP to OUT delay COMP set to 2V 20 ns
CS stepped 0 to 0.4V,
time to OUT transition
low, C
load
= 0.
Min Duty Cycle COMP = 0V 0 %
Max Duty Cycle (-1 Device) 75 80 85 %
Max Duty Cycle (-2 Device) 50 %
COMP to PWM comparator gain 0.33
COMP Open Circuit Voltage 4.2 5.1 6 V
COMP at Max Duty Cycle 2.75 V
COMP Short Circuit Current COMP = 0V 0.6 1.1 1.5 mA
SLOPE COMPENSATION
Slope Comp Amplitude (LM5021-1 CS pin to PWM 70 90 110 mV
only) Comparator offset at
maximum duty cycle
OUTPUT SECTION
OUT High Saturation IOUT = 50mA, VCC - 0.6 1.1 V
OUT
OUT Low Saturation IOUT = 100mA 0.3 1 V
Peak Source Current OUT = VCC/2. 0.3 A
Peak Sink Current OUT = VCC/2. 0.7 A
Rise time C
load
= 1nF 25 ns
Fall time C
load
= 1nF 10 ns
HICCUP MODE
V
OVLD
Over load detection threshold COMP pin V
SS-OCV
– 0.8 V
SS-OCV
– 0.6 V
SS-OCV
– 0.4 V
V
HIC
Hiccup mode threshold SS pin V
SS-OCV
– 0.8 V
SS-OCV
– 0.6 V
SS-OCV
– 0.4 V
V
RST
Hiccup mode Restart threshold SS pin 0.1 0.3 0.5 V
I
DTCS
Dead-time current source 0.1 0.25 0.4 µA
I
OVCS
Overload detection timer current 6 10 14 µA
source
THERMAL RESISTANCE
θ
JA
VSSOP-8 Junction to Ambient 0 LFM 200 °C/W
θ
JA
PDIP-8 Junction to Ambient 0 LFM 107 °C/W
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