March 2009 Rev 8 1/20
20
ST890
1.2 A current limited high side power switch
with thermal shutdown
Features
■2.7 V to 5.5 V input range
■Programmable current limit up to 1.2 A
■Low quiescent current
■Thermal shutdown
■Active low FAULT indicator output
■90 mΩ (typ.) ON resistance
■SO-8 and DFN8L (3 x 3 mm) packages
Applications
■PCMCIA slots
■Access bus slots
■Portable equipment
Description
The ST890 is a low voltage, P-channel MOSFET
power switch intended for high side load switching
applications.
The switch operates with inputs from 2.7 V to
5.5 V, making it ideal for both 3 V and 5 V
systems.
The internal current limiting circuitry protects the
input supply against overload. The thermal
overload protection limits power dissipation and
junction temperatures.
The maximum current limit is 1.2 A. The current
limit through the switch is programmed with a
resistor from SET to ground. The devices are
available in SO-8 and DFN8L (3 x 3 mm)
packages.
DFN8L
(3x3mm)
SO-8
Table 1. Device summary
Order code Package Packaging
ST890BDR SO-8 2500 parts per reel
ST890CDR SO-8 2500 parts per reel
ST890DTR DFN8L (3 x 3 mm) 3000 parts per reel
www.st.com
Contents ST890
2/20
Contents
1 Device summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 Maximum rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.1 Functional description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.1.1 Output current limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.1.2 Output short circuit protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.1.3 Programming ILIM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.1.4 Fault pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.1.5 Thermal protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.2 Typical performance characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
ST890 Device summary
3/20
1 Device summary
Figure 1. SO-8 pin connection (top view)
Table 2. SO-8 pin description
Pin N. Symbol Name and function
1, 2 IN Input P-channel MOSFET source. Bypass IN with a 1 μF
capacitor to ground
3ON
Active low switch ON input. A logic low turns the switch ON
4 GND Ground
5 SET
Set current limit input. A resistor from SET to GND sets the
current limit for the switch. RSET = 1.24x1110/ ILIM, where
ILIM is the desired current limit in Amperes
6,7 OUT Switch output. P-channel MOSFET drain. Bypass OUT with
a 0.1 μF capacitor to ground
8FAULT
Fault indicator output. This open drain output goes low
when in current limit or when the die temperature exceeds
135°C
1
2
3
4
8
7
6
5
IN
IN
ON
GND
FAULT
OUT
OUT
SET
CS07570
Device summary ST890
4/20
Figure 2. DFN8L (3 x 3 mm) pin connection (top view)
Table 3. DFN8L (3 x 3 mm) pin description
Pin N. Symbol Name and function
1, 2 IN Input P-channel MOSFET source. Bypass IN with a 1 μF
capacitor to ground
3ON
Active low switch ON input. A logic low turns the switch ON
4 GND Ground
5 SET Set current limit input. A resistor from SET to GND sets the
current limit for the switch.
6,7 OUT
Switch output. P-channel MOSFET drain. Bypass OUT with
a 0.1 μF capacitor to ground.
RSET = 1.24x1110/ILIM, where ILIM is the desired current
limit in Amperes
8FAULT
Fault indicator output. This open drain output goes low
when in current limit or when the die temperature exceeds
135 °C
1
2
3
4
8
7
6
5
IN
IN
ON
GND
FAULT
OUT
OUT
SET
CS00025
ST890 Device summary
5/20
Figure 3. Schematic diagram
Table 5. Truth table for FAULT
Table 4. Truth table for ON/OFF switch
ON/OFF OUT
LON
HOFF
FAULT FLAG
H Normal operation
L Fault condition
OUT
/FAULT
IN
/ON
+
-
ON
ON
-
+
Control
circuitry
SET
1.24V
Current limit
amplifier
Replica
amplifier
GND
CS00026
Maximum rating ST890
6/20
2 Maximum rating
Stressing the device above the rating listed in the “Absolute maximum ratings” table may
cause permanent damage to the device. These are stress ratings only and operation of the
device at these or any other conditions above those indicated in the operating sections of
this specification is not implied. Exposure to Absolute maximum rating conditions for
extended periods may affect device reliability. Refer also to the STMicroelectronics SURE
Program and other relevant quality documents.
Table 7. Thermal data
Table 6. Absolute maximum ratings
Symbol Parameter Value Unit
VISupply voltage -0.5 to +6 V
VON Input voltage at ON pin -0.5 to +6 V
VFAULT_N Input voltage at FAULT_N pin -0.5 to +6 V
VSET Voltage at SET pin -0.5 to (VIN +0.5) V
IDS Maximum continuous switching current 1.5 A
Tstg Storage temperature -65 to +150 °C
Top Operating ambient temperature range -40 to +85 °C
Symbol Parameter SO-8 DFN8L Unit
Rthj-amb
Thermal
resistance
junction-ambient
160(1)
1. This value depends from thermal design of PCB on which the device is mounted.
37.6(2)
2. This value depends from the 4-layer PCB, JEDEC standard test board.
°C/W
Table 8. Electrical characteristics
Symbol Parameter Test condition(1)
Value
Unit
TA = 25°C
Min Typ Max
VIOperating voltage ID=1mA 2.7 5.5 V
ICC
ON quiescent
supply current
VI=5V,
ON = GND
IO = 0
13 25 μA
I(CCOFF)
OFF quiescent
supply current
ON =IN
VI=V
OUT =5.5V 1
μA
ON =IN
VI=5.5V
VO=0
5
ST890 Maximum rating
7/20
VULO Undervoltage
lockout
Rising edge 2.0 2.4 2.6 V
VHYST Undervoltage
lockout hysteresis
100 mV
RON ON resistance VI = 4.5 V 75 120 mΩ
VI = 3 V 90 130 mΩ
VSET Reference voltage
to turn the switch
OFF
IO = 100 mA
VSET rise until VI-V
O>
0.8V
1.178 1.24 1.302
V
IMAX Maximum
programmable
output over
current limit
1.2
A
ISC Short circuit
current limit
VI = 5V, OUT connected
to GND, device enabled
into short circuit
1.2 ILIM 1.5 ILIM A
ILIM/ISET ILIM to ISET current
ratio
IO=500mA
VO>1.6V 970 1110 1300
VIL ON input low level
voltage VI= 2.7 to 5.5 V 0.8 V
VIH ON input high
level voltage
VI= 2.7 to 3.6 V 2.0 V
VI= 2.7 to 5.5 V 2.4 V
IION input leakage
current VI=5.5V 1 μA
ISET bias ISET bias current
VSET =1.24V
IO=0
A
VI=V
O
0.5 3 μA
VOL
FAULT output low
voltage
ISINK =1 mA
VSET = 1.4 V 0.15 V
IOH
FAULT output high
voltage
VFAULT =5.5V
VSET =1V 1μA
TPROT
Thermal
protection 130 °C
THYST
Thermal
hysteresis 15 °C
1. VIN =3V, T
A=T
MIN to TMAX, unless otherwise specified. Typical values are at TA=25°C
Table 8. Electrical characteristics (continued)
Symbol Parameter Test condition(1)
Value
Unit
TA = 25°C
Min Typ Max
Maximum rating ST890
8/20
Table 9. Timing characteristics
Figure 4. Typical application circuit
Symbol Parameter Test condition(1)
1. VIN =3V, T
A=T
MIN to TMAX, unless otherwise specified. Typical values are at TA = 25 °C
Value
UnitTA = 25°C
Min Typ Max
tRESP
Slow current loop
response time
20% current overdrive,
VCC =5 V 5μs
Fast current loop
response time 2μs
tON Turn ON time
VI=5 V
IO = 500 mA 25 50 μs
VI=3V
IO = 500 mA 50 μs
tOFF Turn OFF time VI=5V 1 2 10 μs
IN
IN
/
FA
U
LT
G
ND
OUT
OUT
/O
N
S
ET
INPUT
OUTPUT
RSET
1μF
100 k Ω
ON/OFF
0.1μF
CS00027
ST890 Maximum rating
9/20
2.1 Functional description
2.1.1 Output current limit
ILIM is the output current that ST890 limits under the condition VO (output voltage) > 1.6 V.
When ILIM is reached, the Fault pin is asserted.
2.1.2 Output short circuit protection
The ST890 provides short circuit protection by limiting the output current during a short
circuit event.
Isc is the output short circuit current limit level (typ 1.2 x ILIM). When the output is short circuit
such as VO < 1.6 V, the ST890 limits the output current to no more than the Isc level.
When the output is short circuit, the Fault pin is asserted.
2.1.3 Programming ILIM
The ST890's ILIM can be programmed through the external resistor, RSET connected at the
SET pin (pin 5).
ILIM is determined by the following relationships:
Equation 1
Equation 2
therefore:
Equation 3
2.1.4 Fault pin
The Fault pin (pin 8) is an open drain active low output. This pin should be connected to an
external pull-up resistor.
The Fault pin is asserted low when:
–I
OUT reaches the programmed ILIM value
– A short circuit event occurs
– The device goes into thermal protection
2.1.5 Thermal protection
The ST890's thermal protection is triggered to turn off the switch when the junction
temperature exceeds 130°C (typ).
SETSETSET R / V = I
1110 = I / I SETLIM
LIMSET I / 1110x 1.24 = R
Maximum rating ST890
10/20
2.2 Typical performance characteristics
Unless otherwise specified Tj = 25 °C.
Figure 5. ON resistance vs. supply voltage
Figure 6. ON resistance vs. temperature
ST890 Maximum rating
11/20
Figure 7. Switching waveforms
VCC=5V, RL=0.6
Ω
VCC=5V, RL=0.32
Package mechanical data ST890
12/20
3 Package mechanical data
In order to meet environmental requirements, ST offers these devices in ECOPACK®
packages. These packages have a Lead-free second level interconnect. The category of
second level interconnect is marked on the package and on the inner box label, in
compliance with JEDEC Standard JESD97. The maximum ratings related to soldering
conditions are also marked on the inner box label. ECOPACK is an ST trademark.
ECOPACK specifications are available at: www.st.com.
Figure 8. SO-8 package drawing
1. Drawing not to scale.
0016023/C
ST890 Package mechanical data
13/20
Table 10. SO-8 package mechanical data
Symbol
millimeters inches
Min Typ Max Min Typ Max
A 1.35 1.75 0.053 0.069
A1 0.10 0.25 0.04 0.010
A2 1.10 1.65 0.043 0.065
B 0.33 0.51 0.013 0.020
C 0.19 0.25 0.007 0.010
D 4.80 5.00 0.189 0.197
E 3.80 4.00 0.150 0.157
e 1.27 0.050
H 5.80 6.20 0.228 0.244
h 0.25 0.50 0.010 0.020
L 0.40 1.27 0.016 0.050
k8°(max)
ddd 0.1 0.04
Package mechanical data ST890
14/20
Figure 9. SO-8 tape and reel specifications
1. Drawing not to scale.
Table 11. SO-8 tape and reel mechanical data
Symbol
millimeters inches
Min Typ Max Min Typ Max
A 330 12.992
C 12.8 13.2 0.504 0.519
D 20.2 0.795
N60 2.362
T22.40.882
Ao 8.1 8.5 0.319 0.335
Bo 5.5 5.9 0.216 0.232
Ko 2.1 2.3 0.082 0.090
Po 3.9 4.1 0.153 0.161
P 7.9 8.1 0.311 0.319
ST890 Package mechanical data
15/20
Figure 10. DFN8L (3 x 3 mm) package drawing
1. Drawing is not to scale.
2. Dimensions in millimeters.
PO8092726_A
Package mechanical data ST890
16/20
Table 12. DFN8L (3 x 3 mm) package mechanical data
Figure 11. DFN8L (3 x 3 mm) footprint recommendations
1. Drawing not to scale.
2. Dimensions in millimeters.
Symbol
millimeters
Min Typ Max
A 0.80 0.85 0.90
A1 0 0.02 0.05
b 0.25 0.030 0.35
D 2.95 3 3.05
D2 2.30 2.40 2.50
E 2.95 3 3.05
E2 1.70 1.80 1.90
e0.65
L 0.25 0.30 0.35
FR8092726_A
ST890 Package mechanical data
17/20
Figure 12. DFN8L (3 x 3 mm) tape and reel specifications
Package mechanical data ST890
18/20
Figure 13. DFN8L (3 x 3 mm) reel specifications
ST890 Revision history
19/20
4 Revision history
Table 13. Document revision history
Date Revision Changes
22-Jul-2005 4 Added 3 rows on Table 2 on page 3
10-Aug-2007 5 Removed ST890CD and ST890BD from Table 1 on page 1
Updated short circuit current limit value in Table 8 on page 6
1-Dec-2007 6
Added Section : Contents.
Added ST890D and related DFN8L package information.
Added Figure 2: DFN8L (3 x 3 mm) pin connection (top view) on
page 4.
Figure 3: Schematic diagram on page 5: redrawn, no content
change.
Modified title in Table 5: Truth table for FAULT on page 5.
Updated Table 8: Electrical characteristics on page 6.
Figure 4: Typical application circuit on page 8: redrawn, no content
change.
13-Oct-2008 7
Updated: Table 2 on page 3, Table 3 on page 4.
Added: Section 2.1: Functional description on page 9 and Figure 12
on page 17.
04-Mar-2009 8 Replaced ST890B, ST890C and ST890D with ST890.
Modified: Table 6: Absolute maximum ratings
ST890
20/20
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