Datasheet

UCC28250
SLUSA29C –APRIL 2010– REVISED JULY 2011 www.ti.com
ELECTRICAL CHARACTERISTICS
(1)
(continued)
VDD = 12 V, 1-µF capacitor from VDD and VREF to GND, T
A
= T
J
= -40°C to 125°C, RT = 75 kΩ connected to ground to set
F
SW
= 200 kHz (unless otherwise noted).
PARAMETER TEST CONDITION MIN TYP MAX UNITS
Oscillator
Nominal switching frequency
F
SW(nom)
at OUTA or OUTB set by RT RT/SYNC = 75 kΩ, R
SP
= 20 kΩ 185 200 215
resistor
kHz
Minimum switching frequency
F
SW(min_sync)
at OUTA or OUTB set by f
RT/SYNC
= 100 kHz 85
external sync frequency
Maximum switching
frequency at OUTA or OUTB
F
SW(max_sync)
f
RT/SYNC
= 2.5 MHz 1.15 MHz
set by external sync
frequency
External synchronization
1
signal high
V
External synchronization
0.2
signal low
Voltage Reference
V
DD
= from 7 V to 17 V, I
VREF
= 2 mA 3.22 3.30 3.38
V
VREF
Output voltage V
0 < I
REF
< 10 mA 3.22 3.30 3.38
Short circuit current V
REF
= 3 V, T
J
= 25°C 12 25 40 mA
Current Sense, Cycle-by-Cycle Current Limit With Hiccup
V
ILIM
ILIM cycle-by-cycle threshold 0.495 0.502 0.509 V
Propagation delay from ILIM
T
PDILIM
Exclude leading edge blanking 15 25 36 ns
to OUTA and OUTB outputs
T
BLANK
leading edge blanking 40 60 90 ns
Current limit shutdown delay
Measured at HICC pin 55 75 95
timing program current
µA
Hiccup timing program
Measured at HICC pin 2 2.7 3.5
current
Current limit shutdown delay
V
HICC_SD
0.55 0.60 0.65
timer threshold at HICC
V
HICC_PU
HICC pull-up threshold 2.3 2.4 2.5
V
V
HICC_RST
Hiccup restart threshold 0.25 0.30 0.35
10-V ramp charging voltage source with 40-kΩ
V
CS(max)
RAMP/CS clamp voltage 3.5 4.0 4.5
current limiting resistor
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