Datasheet

LM2745, LM2748
SNOSAL2E –APRIL 2005–REVISED APRIL 2013 www.ti.com
Electrical Characteristics (continued)
V
CC
= 3.3V unless otherwise indicated. Typicals and limits appearing in plain type apply for T
A
= T
J
= 25°C. Limits appearing in
boldface type apply over full Operating Temperature Range. Datasheet min/max specification limits are specified by design,
test, or statistical analysis.
Symbol Parameter Conditions Min Typ Max Units
V
EAO
Error Amplifier Output Voltage Minimum 1 V
Maximum 2.2 V
GATE DRIVE
I
Q-BOOT
BOOT Pin Quiescent Current V
BOOT
= 12V, V
SD
= 0 18 90 µA
R
HG_UP
High-Side MOSFET Driver Pull-Up
V
BOOT
= 5V @ 350 mA Sourcing 2.7 Ω
ON resistance
R
HG_DN
High-Side MOSFET Driver Pull-Down
350 mA Sinking 0.8 Ω
ON resistance
R
LG_UP
Low-Side MOSFET Driver Pull-Up
V
BOOT
= 5V @ 350 mA Sourcing 2.7 Ω
ON resistance
R
LG_DN
Low-Side MOSFET Driver Pull-Down
350 mA Sinking 0.8 Ω
ON resistance
OSCILLATOR
R
FADJ
= 750 kΩ 50
R
FADJ
= 100 kΩ 300
PWM Frequency
R
FADJ
= 42.2 kΩ 475 600 725
f
SW
kHz
R
FADJ
= 18.7 kΩ 1000
LM2745 External Synchronizing
Voltage Swing = 0V to V
CC
250 1000
Signal Frequency
LM2745 Synchronization Signal Low
SYNC
L
f
SW
= 250 kHz to 1 MHz 1 V
Threshold
LM2745 Synchronization Signal High
SYNC
H
f
SW
= 250 kHz to 1 MHz 2 V
Threshold
D
MAX
Max High-Side Duty Cycle f
SW
= 300 kHz 86
f
SW
= 600 kHz 78 %
f
SW
= 1 MHz 67
LOGIC INPUTS AND OUTPUTS
V
STBY-IH
Standby High Trip Point V
FB
= 0.575V, V
BOOT
= 3.3V 1.1
V
V
SD
Rising
V
STBY-IL
Standby Low Trip Point V
FB
= 0.575V, V
BOOT
= 3.3V 0.232
V
V
SD
Falling
V
SD-IH
SD Pin Logic High Trip Point V
SD
Rising 1.3 V
V
SD-IL
SD Pin Logic Low Trip Point V
SD
Falling 0.8 V
V
PWGD-TH-LO
PWGD Pin Trip Points V
FB
Falling 0.408 0.434 0.457 V
V
PWGD-TH-HI
PWGD Pin Trip Points V
FB
Rising 0.677 0.710 0.742 V
V
PWGD-HYS
PWGD Hysteresis V
FB
Falling 60
mV
V
FB
Rising 90
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