Datasheet

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TPS51120
SLUS670B – JULY 2005 – REVISED FEBRUARY 2007
ELECTRICAL CHARACTERISTICS (continued)
over operating free-air temperature range, V
VIN
= 12 V, V
VREG5
= V
V5FILT
= 5 V (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
ON-TIME TIMER, INTERNAL SOFT-START and HOUSEKEEPING CLOCK
T
ON1a
On time, 5V, 180 kHz V
LL1
=12V, V
OUT1
=5V, TONSEL=5V, T
A
= 25 ° C 2150 2340 2530
T
ON1b
On time, 5V, 220 kHz V
LL1
=12V, V
OUT1
=5V, TONSEL=FLOAT, T
A
= 25 ° C 1790 1950 2110
T
ON1c
On time, 5V, 280 kHz V
LL1
=12V, V
OUT1
=5V, TONSEL=2V, T
A
= 25 ° C 1370 1490 1610
T
ON1d
On time, 5V, 380 kHz V
LL1
=12V, V
OUT1
=5V, TONSEL=GND, T
A
= 25 ° C 1020 1110 1200
T
ON2a
On time, 3.3V, 270 kHz V
LL2
=12V, V
OUT2
=3.3V, TONSEL=5V, T
A
= 25 ° C 940 1030 1120
V
LL2
==12V, V
OUT1
=3.3V, TONSEL=FLOAT, T
A
=
T
ON2b
On time, 3.3V, 330 kHz 780 850 920 ns
25 ° C
T
ON2c
On time, 3.3V, 430 kHz V
LL2
==12V, V
OUT1
=3.3V, TONSEL=2V, T
A
= 25 ° C 580 650 720
T
ON2d
On time, 3.3V, 580 kHz V
LL2
==12V, V
OUT1
=3.3V, TONSEL=GND, T
A
= 25 ° C 430 480 530
T
ON(MIN)1
Minimum on time, 5V T
A
= 25 ° C, TONSEL=GND, V
LL1
=28V, VO1=1V 70
T
ON(MIN)2
Minimum on time, 3.3V T
A
= 25 ° C, TONSEL=GND, V
LL2
=28V, VO2=1V 45
T
OFF(MIN)
Minimum off time T
A
= 25 ° C, VFB=0.9V, LL=0.5V 480
T
SS
Internal Soft Start Timer T
A
= 25 ° C, ENx>3V 772 clks
SL
SS
Internal Soft Start Slope T
A
= 25 ° C, ENx>3V, Slope wrt. VFB
(2)
0.3 V/ms
F
CLK
HK clock frequency 230 290 350 kHz
UVLO/LOGIC THRESHOLD
EN3, EN5, low to high 0.3 0.6 0.8
V
ENLDOH
LDO enable threshold
Hysteresis 0.2
V
V
ENLDOFL3
EN3 pullup voltage EN3 = FLOAT (OPEN)
(2)
1.7
V
ENLDOFL5
EN5 pullup voltage EN5= FLOAT (OPEN)
(2)
3.3
I
ENLDOFL
EN3, EN5 pullup current VENx < 0.5V 1.5 4.0 µ A
Wake up 3.8 4.0 4.2 V
V
UV(VREG5)
VREG5 UVLO threshold
Hysteresis 100 200 300 mV
Auto-SKIP Mode Enabled 0 0.7
V
SKIPSEL
SKIPSEL threshold Auto-SKIP Mode Enabled, Faults Off 1.3 2.2
PWM-Only Mode Enabled 2.7 5.5
Fast Switching Frequency 0 0.7 V
Medium Switching Frequency #2 1.3 2.2
V
TONSEL
TONSEL threshold
Medium Switching Frequency #1 2.7 3.0
Slow Switching Frequency 4.5 5.5
SKIPSEL, TONSEL=0V 1 3
I
SEL
SKIPSEL/TONSEL input current µ A
SKIPSEL, TONSEL=5V 1 2
V
ENSWSTAT
EN1, EN2 SS Start Voltage BJT Base input, Switcher begins to Track ENx 0.5 0.9 1.2
V
‘Logic High’ Level for Switcher Enable when using
V
ENSWEND
EN1, EN2 SS End Voltage 2.75 2.90
Internal Softstart, 0 ° C ≤ T
A
≤ 85 ° C
I
ENSW1,2
EN1, EN2 Pullup Current EN1, EN2=0.6V 1 2 3 µ A
V
THVFB1
VFB1 threshold 5.0V preset output V5FILT -0.3
V
V
THVFB2
VFB2 threshold 3.3V preset output V5FILT -0.3
CURRENT SENSE
Resistor sense scheme , V
PGND - VCS
voltage,
V
OCL
Current limit threshold 67 80 93 mV
PGOOD=Hi
I
TRIP
CS Sink Current R
DS(ON)
sense scheme, PGOOD=Hi, T
A
= 25 ° C 9 10 11 µ A
ppm/ °
TC
ITRIP
I
TRIP
temperature Coefficient R
DS(ON)
sense scheme, On the basis of 25 ° C 4500
C
(2) Ensured by design. Not production tested.
6
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