Datasheet

TPS51218
SLUS935B –MAY 2009–REVISED FEBRUARY 2012 www.ti.com
ELECTRICAL CHARACTERISTICS
over recommended free-air temperature range, V5IN=5V. (Unless otherwise noted)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
SUPPLY CURRENT
V5IN current, T
A
= 25°C, No Load,
I
V5IN
V5IN supply current 320 500 μA
V
EN
= 5 V, V
VFB
= 0.735 V
I
V5INSDN
V5IN shutdown current V5IN current, T
A
= 25°C, No Load, V
EN
= 0 V 1 μA
INTERNAL REFERENCE VOLTAGE
VFB voltage, CCM condition
(1)
0.7000 V
T
A
= 25°C, skip mode 0.7005 0.7040 0.7075
V
VFB
VFB regulation voltage
T
A
= 0°C to 85°C, skip mode 0.6984 0.7040 0.7096 V
T
A
= –40°C to 85°C, skip mode 0.6970 0.7040 0.7110
I
VFB
VFB input current V
VFB
= 0.735 V, T
A
= 25°C, skip mode 0.01 0.2 μA
OUTPUT DISCHARGE
Output discharge current from
I
Dischg
V
EN
= 0 V, V
SW
= 0.5 V 5 13 mA
SW pin
OUTPUT DRIVERS
Source, I
DRVH
= –50 mA 1.5 3
R
DRVH
DRVH resistance
Sink, I
DRVH
= 50 mA 0.7 1.8
Ω
Source, I
DRVL
= –50 mA 1.0 2.2
R
DRVL
DRVL resistance
Sink, I
DRVL
= 50 mA 0.5 1.2
DRVH-off to DRVL-on 7 17 30
t
D
Dead time ns
DRVL-off to DRVH-on 10 22 35
BOOT STRAP SWITCH
V
FBST
Forward voltage V
V5IN-VBST
, I
F
= 10 mA, T
A
= 25°C 0.1 0.2 V
I
VBSTLK
VBST leakage current V
VBST
= 34.5 V, V
SW
= 28 V, T
A
= 25°C 0.01 1.5 μA
DUTY AND FREQUENCY CONTROL
t
OFF(min)
Minimum off-time T
A
= 25°C 150 260 400
ns
V
IN
= 28 V, V
OUT
= 0.7 V, R
RF
= 39kΩ,
t
ON(min)
Minimum on-time 79
T
A
= 25°C
(1)
SOFTSTART
t
ss
Internal SS time From V
EN
= high to V
OUT
= 95% 1 ms
POWERGOOD
PG in from lower 92.5% 95% 97.5%
V
THPG
PG threshold PG in from higher 107.5% 110% 112.5%
PG hysteresis 2.5% 5% 7.5%
I
PGMAX
PG sink current V
PGOOD
= 0.5 V 3 6 mA
t
PGDEL
PG delay Delay for PG in 0.8 1 1.2 ms
LOGIC THRESHOLD AND SETTING CONDITIONS
Enable 1.8
V
EN
EN voltage threshold V
Disable 0.5
I
EN
EN input current V
EN
= 5V 1.0 μA
R
RF
= 470 kΩ, T
A
= 25°C
(2)
266 290 314
R
RF
= 200 kΩ, T
A
= 25°C
(2)
312 340 368
f
SW
Switching frequency kHz
R
RF
= 100 kΩ, T
A
= 25°C
(2)
349 380 411
R
RF
= 39 kΩ, T
A
= 25°C
(2)
395 430 465
CCM 1.8
V
RF
CCM setting voltage V
Auto-skip 0.5
(1) Ensured by design. Not production tested.
(2) Not production tested. Test condition is V
IN
= 8 V, V
OUT
= 1.1 V, I
OUT
= 10 A using application circuit shown in Figure 21.
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