Specifications

2
BAT OUT
HSD OUT(MAX)
2
V V
1
E L I
2
R

u u
BAT OUT
OUT(MAX) OUT
OUT(MAX) OUT
HSD
2
OUT
V V
R I V
( / 5 , ± 9 OQ
V
R
ª º

§ ·
u 
« »
u u u
¨ ¸
¨ ¸
« »
© ¹
¬ ¼
OUT(MAX) OUT
DECAY
OUT
R I V
L
T ln
R
V
§ ·
u 
¨ ¸
u
¨ ¸
© ¹
DECAY
T
HSD DS,clamp OUT
0
E V I (t)dt u
³
HSD BAT LOAD BAT L R
( ( ( ( ( ± (  
DS,clamp BAT OUT
9 9 ± 9
CL,th CL,th CL
out
CL CL
CL CL out
V V K
I
I R
R K I
u
o
TPS1H100-Q1
www.ti.com SLVSCM2A –OCTOBER 2014–REVISED JANUARY 2014
Feature Description (continued)
current applications, the CL pin should be tied directly to the device GND.
Both internal current limit (I
lim,nom
) and external programmable current limit are always active when V
S
is powered
and IN is high level. The smaller one (of I
lim,nom
and external programmable current limit) is applied as the actual
current limit.
Note that if a GND network is used (which leads to the level shift between the device GND and board GND), the
CL pin must be connected with device GND. Calculate the R
CL
with Equation 2.
(2)
For better protection from the hard short to GND condition (when V
S
and input are high and a short to GND
happens suddenly), an open loop fast-response behavior is set to turn off the channel, before the current limit
closed loop is set-up. The open loop response time is around 1 µs. With this fast response, the device can
achieve better inrush suppression performance.
8.3.3 Inductive Load Switching-Off Clamp
When inductive load is switching off, output voltage is pulled down to negative, due to the inductance
characteristics. The power FET may break down if the voltage is not clamped during the demagnetization. To
protect the power FET in this situation, internally clamp the drain-to-source voltage, namely V
DS,clamp
, the clamp
diode between the drain and gate.
(3)
During the duty of demagnetization (T
DECAY
), the power FET is turned on for inductance energy dissipation. Both
the energy of the power supply (E
BAT
) and the load (E
LOAD
) are dissipated on the high-side power switch itself,
which is called E
HSD
. If resistance is in series with inductance, some of the load energy will be dissipated on the
resistance.
(4)
From the high-side power switch’s view, E
HSD
equals the integration value during the demagnetization duty.
(5)
(6)
(7)
When R approximately equals 0, E
HSD
can be given simply as:
(8)
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