Datasheet

LM5045
SNVS699G –FEBRUARY 2011–REVISED MARCH 2013 www.ti.com
Electrical Characteristics (continued)
Limits in standard typeface are for T
J
= 25°C only; limits in boldface type apply the junction temperature range of -40°C to
+125°C. Unless otherwise specified, the following conditions apply: VIN = 48V, RT = 25kΩ, RD1=RD2=20kΩ. No load on
HO1, HO2, LO1, LO2, SR1, SR2, COMP=0V, UVLO=2.5V, OVP=0V, SSOFF=0V.
Symbol Parameter Conditions Min Typ Max Units
V
REF
REF Voltage I
REF
= 0mA 4.85 5 5.15 V
REF voltage regulation I
REF
= 0 to 10mA 25 50 mV
I
REF(Lim)
REF current limit V
REF
= 4.5V 15 20 mA
V
REFUV
V
REF
under-voltage threshold Positive going V
REF
4.3 4.5 4.7 V
Hysteresis 0.25 V
Under-Voltage Lock Out and shutdown (UVLO pin)
V
UVLO
Under-voltage threshold 1.18 1.25 1.32 V
I
UVLO
Hysteresis current UVLO pin sinking current when 16 20 24 µA
V
UVLO
<1.25V
Under-voltage standby enable UVLO voltage rising 0.32 0.4 0.48 V
threshold
Hysteresis 0.05 V
V
OVP
OVP shutdown threshold OVP rising 1.18 1.25 1.32 V
OVP hysteresis current OVP sources current when OVP>1.25V 16 20 24 µA
Soft-Start (SS Pin)
I
SS
SS charge current V
SS
= 0V 16 20 24 µA
SS threshold for SSSR charge current I
COMP
<800µA 1.93 2.0 2.20 V
enable
SS output low voltage Sinking 100µA 40 mV
SS threshold to disable switching 200 mV
I
SSSR
SSSR charge current V
SS
>2V, I
COMP
<800µA 16 20 24 µA
I
SSSR-DIS1
SSSR discharge current 1 V
UVLO
<1.25V 54 65 75 µA
I
SSSR-DIS2
SSSR discharge current 2 V
RES
>1V 109 125 147 µA
SSSR output low voltage Sinking 100µA 50 mV
SSSR threshold to enable SR1/SR2 1.2 V
Current Sense Input (CS Pin)
V
CS
Current limit threshold 0.710 0.750 0.785 V
CS delay to output 65 ns
CS leading edge blanking 50 ns
R
CS
CS sink impedance (clocked) Internal FET sink impedance 18 45 Ω
Soft-Stop Disable (SS OFF Pin)
V
IH(min)
SSOFF Input-threshold 2.8 V
SSOFF pull down resistance 200 kΩ
Current Limit Restart (RES Pin)
R
RES
RES pull-down resistance Termination of hiccup timer 37 Ω
V
RES
RES hiccup threshold 1 V
RES upper counter threshold 4 V
RES lower counter threshold 2 V
I
RES-SRC1
Charge current source 1 V
RES
<1V,V
CS
>750mV 30 µA
I
RES-SRC2
Charge current source 2 1V<V
RES
<4V 10 µA
I
RES-DIS2
Discharge current source 1 V
CS
<750mV 5 µA
I
RES-DIS2
Discharge current source 2 2V<V
RES
<4V 5 µA
Ratio of time in hiccup mode to time V
RES
>1V, Hiccup counter 147
in current limit
Voltage Feed-Forward (RAMP Pin)
RAMP sink impedance (Clocked) 5.5 20 Ω
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