MICREL MIC2544-1

Micrel
MIC2544/2548
MIC2544/2548
Programmable Current Limit High-Side Switch
Preliminary Information
General Description
Features
The MIC2544 and MIC2548 are integrated high-side power
switches optimized for low loss dc power switching and other
power management applications, including Advanced Configuration and Power Interface (ACPI). The MIC2544/48 is a
cost-effective, highly integrated solution that requires few
external components to satisfy USB and ACPI requirements.
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Load current management features include a precision resistor-programmable output current-limit and a soft-start circuit
which minimizes inrush current when the switch is enabled.
Thermal shutdown, along with current-limit, protects the
switch and the attached device.
The MIC2544/48’s open-drain flag output is used to indicate
current-limiting or thermal shutdown to a local controller. The
MIC2548 has an additional internal latch which turns the
output off upon thermal shutdown providing robust fault
control. The enable signal is compatible with both 3V and 5V
logic, and is also used as the thermal shutdown latch reset for
the MIC2548.
The MIC2544 and MIC2548 are available in active-high and
active-low enable versions in the 8-pin SOP (small-outline
package) and 8-pin MSOP (micro-small-outline package).
2.7V to 5.5V input
Adjustable current-limit up to 1.5A
Reverse current flow blocking (no “body diode”)
75µA typical on-state supply current
1µA typical off-state supply current
120mΩ maximum on-resistance
Open-drain fault flag
Thermal shutdown
Thermal shutdown output latch (MIC2548)
2ms (slow) turn-on and fast turnoff
Available with active-high or active-low enable
Applications
•
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USB power distribution
PCI Bus Power Switching
Notebook PC
ACPI power distribution
PC card hot swap applications
Inrush current-limiting
Typical Application
+5V
RFLG
On/Off
MIC2544-xBM
EN
OUT
FLG
IN
GND
OUT
NC
ILIM
RSET
0.1µF
Peripheral
33µF
SOP pinout shown
Typical Advanced Configuration and Power Interface (ACPI) Application
Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com
June 2000
1
MIC2544/2548
Micrel
MIC2544/2548
Ordering Information
Part Number
Enable
Temperature Range
Package
MIC2544-1BM
Active High
Latch*
–40°C to +85°C
8-pin SOP
MIC2544-1BMM
Active High
–40°C to +85°C
8-pin MSOP
MIC2544-2BM
Active Low
–40°C to +85°C
8-pin SOP
MIC2544-2BMM
Active Low
–40°C to +85°C
8-pin MSOP
MIC2548-1BM
Active High
•
–40°C to +85°C
8-pin SOP
MIC2548-1BMM
Active High
•
–40°C to +85°C
8-pin MSOP
MIC2548-2BM
Active Low
•
–40°C to +85°C
8-pin SOP
MIC2548-2BMM
Active Low
•
–40°C to +85°C
8-pin MSOP
* Thermal Shutdown Latch
Pin Configuration
MIC2544/2548
MIC2544/2548
EN
1
8
OUT
FLG
2
7
GND
3
ILIM
4
EN
1
8
OUT
IN
FLG
2
7
IN
6
OUT
GND
3
6
OUT
5
NC
NC
4
5
ILIM
8-Pin SOP (M)
8-Pin MSOP (MM)
MIC2544/2548
(OUT)
(EN)
(FLG)
LOGIC,
CHARGE
PUMP
NOTE: PINS 4 AND 5
FOR SOIC AND MSOP
ARE DIFFERENT.
(IN)
(ILIM)
(GND)
Pin Description
Pin Number
MSOP-8
Pin Number
SOP-8
Pin Name
1
1
EN
Enable (Input): Logic-compatible enable input. Active-high (-1) or active-low
(-2). High input >1.7V typical; low input <1.5V typical. Do not float.
MIC2548 only: Also resets thermal shutdown latch.
2
2
FLG
Fault Flag (Output): Active-low, open-drain output. Indicates overcurrent or
thermal shutdown conditions.
MIC2548 only: latched low on thermal shutdown.
3
3
GND
Ground
5
4
ILIM
Current Limit: Sets current-limit threshold using an external resistor, RSET,
connected to ground. 154Ω < RSET < 2.29kΩ.
7
7
IN
6,8
6,8
OUT
4
5
NC
MIC2544/2548
Pin Function
Input: Output MOSFET drain. Also powers internal circuitry.
Switch (Output): Output MOSFET source. Pins 6 and 8 must be externally
connected.
Not internally connected
2
June 2000
Micrel
MIC2544/2548
Absolute Maximum Ratings (Note 1)
Operating Ratings (Note 2)
Supply Voltage (VIN) .................................................. +6.0V
Output Voltage (VOUT) ............................................... +6.0V
Output Current (IOUT) ............................... Internally Limited
Enable Input (VEN) ................................. –0.3V to VIN+0.3V
Fault Flag Voltage (VFLG) ........................................... +6.0V
Fault Flag Current (IFLG) ............................................ 50mA
Storage Temperature (TS) ....................... –65°C to +150°C
Junction Temperature (TJ) ....................... Internally Limited
Lead Temperature (soldering 5 sec.) ........................ 260°C
ESD Rating, Note 3 ...................................................... 2kV
Supply Voltage (VIN) ................................... +2.7V to +5.5V
Current Limit Set Range .................................. 0.1A to 1.5A
Ambient Temperature Range (TA) ............. –40°C to +85°C
Package Thermal Resistance
SOP (θJA) .......................................................... 160°C/W
MSOP (θJA) ....................................................... 206°C/W
Electrical Characteristics
VIN = +5V; TA = 25°C, bold indicates –40°C to +85°C; unless noted
Symbol
VEN
Parameter
Condition
Supply Current
Enable Input Voltage
Enable Input Current
RDS(on)
Min
Typ
Max
Units
switch off, OUT = open, Note 4
0.75
5
µA
switch on, OUT = open, Note 4
75
160
µA
enable high, Note 4
2.4
1.7
V
enable low, Note 1
1.5
0.8
V
VEN = VOH(min) = 2.4V
0.01
1
µA
VEN = VOL(max) = 0.8V
0.01
1
µA
Enable Input Capacitance
Note 6
1
pF
Switch Resistance
IOUT = 500mA
80
120
mΩ
Current Limit Factor
IOUT = 100mA to 1A, VOUT = 1V to 4V, Note 5
184
230
276
V
IOUT = 500mA to 1.5A, VOUT = 1V to 4V, Note 5
161
230
299
V
1
10
µA
Output Leakage Current
switch off
tON
Output Turn-On Delay
RL = 10Ω, CL = 1µF, Figures 1a, 1b
1
2
5
ms
tR
Output Turn-On Rise Time
RL = 10Ω, CL = 1µF, Figures 1a, 1b
1
2
5
ms
tOFF
Output Turnoff Delay
RL = 10Ω, CL = 1µF, Figures 1a, 1b
22
µs
tF
Output Turnoff Fall Time
RL = 10Ω, CL = 1µF, Figures 1a, 1b
21
µs
Overtemperature Threshold
TJ increasing
140
°C
Shutdown
TJ decreasing
130
°C
Error Flag Output Resistance
VIN = 5V, IL = 10µA
4
15
Ω
VIN = 3.3V, IL = 10µA
5
20
Ω
0.01
1
µA
Error Flag Off Current
VFLG = 5V
EN Pulse Reset Width
MIC2548 thermal shutdown latch
5
µs
VIN to EN Set-Up
MIC2548, Note 6
0
µs
Current-Limit Response Time
VOUT = 0V, Note 6
25
µs
Overcurrent Flag Response Time
VOUT = VIN/2 to FLG low
5
µs
Note 1.
Exceeding the absolute maximum rating may damage the device.
Note 2.
The device is not guaranteed to function outside its operating rating.
Note 3.
Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF.
Note 4.
Off is ≤ 0.8V and on is ≥ 2.4V for the MIC2544-1 and MIC2548-1. Off is ≥ 2.4V and on is ≤ 0.8V for the MIC2544-2 and MIC2548-2. The
enable input has about 200mV of hysteresis.
Note 5.
230V
Current limit threshold is determined by ILIMIT = R
, where RSET is in ohms.
SET
Note 6.
Guaranteed by design but not production tested.
June 2000
3
MIC2544/2548
Micrel
MIC2544/2548
Test Circuit
VOUT
Device
Under OUT
Test
IOUT
RL
CL
tr
tf
90%
90%
VOUT
10%
10%
Functional Characteristics Test Circuit
Timing Diagrams
VEN
50%
tOFF
tON
90%
VOUT
10%
Figure 1a. MIC2544/48-1
VEN
50%
tOFF
tON
VOUT
90%
10%
Figure 1b. MIC2544/48-2
MIC2544/2548
4
June 2000
Micrel
MIC2544/2548
Output Reset
EN
Short-Circuit Fault
VOUT
ILIMIT
IDC
IOUT
Fault Removed
Thermal Shutdown
Reached
FLG
Figure 2a. MIC2548-2 Timing: Output is reset by toggling EN
EN
Short-Circuit
Fault
Fault
Removed
VOUT
ILIMIT
IDC
IOUT
Thermal Shutdown
Reached
FLG
Figure 2b. MIC2544-2 Timing
June 2000
5
MIC2544/2548
Micrel
MIC2544/2548
Typical Characteristics
Output On-Resistance
vs. Supply Voltage
Output On-Resistance
vs. Temperature
80
TA = 27°C
70
60
3.0 3.5 4.0 4.5 5.0
SUPPLY VOLTAGE (V)
100
3.3V
5.0V
60
80
60
40
20
5.0V
3.3V
60
2.7V
20
0.3
5.0V
0.2
3.3V
0.1
2.7V
0
-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
0
-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
Enable Threshold Voltage
vs. Supply Voltage
Enable Threshold Voltage
vs. Temperature
2.0
0.09
0.08
0.06
0.05
0.04
0.03
0.02
0.01
0
2.5
1.6
1.5
1.4
1.3
VEN FALLING
1.2
1.1
1.0
2.5
3.0 3.5 4.0 4.5 5.0
SUPPLY VOLTAGE (V)
1.8
VEN RISING
1.6
1.4
VEN FALLING
1.2
1.0
-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
5.5
Output Fall Time
vs. Temperature
2.5
2000
1.0
3.3V
5.0V
0.5
CURRENT LIMIT (mA)
1.5
2.7V
1000
ITH
ISHORT
0
-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
MIC2544/2548
0
100
1000
RSET (Ω)
6
3.3V
4
3
5.0V
2
1
RL = 44Ω
Output Current
vs. Output Voltage
1500
ISET
2.7V
5
2000
VIN = 5V
500
6
0
-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
Current Limit
vs. RSET
RL = 44Ω
2.0
5.5
7
OUTPUT RISE TIME (ms)
VEN RISING
1.7
3.0 3.5 4.0 4.5 5.0
SUPPLY VOLTAGE (V)
Rise Time
vs. Temperature
OUTPUT CURRENT (mA)
1.8
ENABLE THRESHOLD (V)
TA = 27°C
TA = 27°C
0.07
2.0
1.9
5.5
0.10
RL = 44Ω
SUPPLY CURRENT (µA)
SUPPLY CURRENT (µA)
100
3.0 3.5 4.0 4.5 5.0
SUPPLY VOLTAGE (V)
Off-State Supply Current
vs. Supply Voltage
Off-State Supply Current
vs. Temperature
120
40
TA = 27°C
100
0
2.5
0.4
80
120
40
-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
5.5
140
SUPPLY CURRENT (µA)
2.7V
80
On-State Supply Current
vs. Temperature
OUTPUT FALL TIME (µs)
SUPPLY CURRENT (mA)
90
50
2.5
ENABLE THRESHOLD (V)
140
120
ON-RESISTANCE (mΩ)
ON-RESISTANCE (mΩ)
100
On-State Supply Current
vs. Supply Voltage
5000
RSET = 150
1500
VIN = 5V
1000
RSET = 470
500
RSET = 2.3k
0
0
1
2
3
4
5
OUTPUT VOLTAGE (V)
6
June 2000
Micrel
MIC2544/2548
Current Limit
vs. Temperature
Current Limit
vs. Supply Voltage
1100
ITH
ITH
CURRENT LIMIT (mA)
OUTPUT CURRENT (mA)
1100
1000
900
VIN = 5V
RSET = 230Ω
ISET
800
700
ISHORT
600
-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
June 2000
1000
900
800
700
600
2.5
7
ISET
TA = 27°C
RL = 230Ω
ISHORT
3.0 3.5 4.0 4.5 5.0
SUPPLY VOLTAGE (V)
5.5
MIC2544/2548
Micrel
MIC2544/2548
Functional Characteristics
VOUT
VFLG
VEN
(2V/div.) (5V/div.) (10V/div.)
Turnoff Response
VIN = 5V
CIN = 4.7µF
VIN = 5V
CIN = 4.7µF
CL = 1µF
RL = 10Ω
MIC2544-1
MIC2544-1
TIME (1ms/div.)
TIME (500µs/div.)
VOUT
VFLG
VEN
(5V/div.) (10V/div.) (10V/div.)
Enable Into Heavy Load
Thermal Shutdown
VIN = 5V
CIN = 4.7µF
RL = 1Ω
ISET = 1A
ISET = 1A
RL = 1Ω
MIC2544-1
MIC2544-1
TIME (100ms/div.)
TIME (100ms/div.)
Enable Into Heavy Load
Inrush Current Response
VOUT
(5V/div.)
VIN = 5V
CIN = 4.7µF
RL = 1Ω
ISET = 1A
VFLG
VEN
(5V/div.) (10V/div.)
VFLG
VEN
(5V/div.) (10V/div.)
VIN = 5V
CIN = 4.7µF
IOUT
(500mA/div.)
IOUT
(500mA/div.)
VOUT
VFLG
VEN
(5V/div.) (10V/div.) (10V/div.)
Current-Limit Response
Reset
VIN = 5V
CIN = 4.7µF
RL = 10Ω
Output Latched
IOUT
(500mA/div.)
CL = 110µF
IOUT
(1A/div.)
Thermal Shutdown
MIC2548-1
CL = 60µF
CL = 10µF
MIC2544-1
TIME (500µs/div.)
MIC2544/2548
CL = 1µF
RL = 10Ω
IOUT
(200mA/div.)
IOUT
(200mA/div.)
VOUT
(2V/div.)
VFLG
VEN
(10V/div.) (5V/div.)
Turn-On Response
TIME (500µs/div.)
8
June 2000
Micrel
MIC2544/2548
Block Diagram
EN
OSC.
THERMAL
SHUTDOWN
1.2V
REFERENCE
CHARGE
PUMP
GATE
CONTROL
RESET
CURRENT
LIMIT
THERMAL
SHUTDOWN
LATCH
(MIC2548)
IN
ILIM
RSET
OUT
FLG
GND
Functional Description
Adjustable Current-Limit
The MIC2544 and MIC2548 are high-side N-channel switches
available with active-high or active-low enable inputs. Fault
conditions turn off or inhibit turn-on of the output transistor
and activate the open-drain error flag transistor making it sink
current to ground.
The short-circuit current-limit is user-adjustable with an external set resistor. Current-limit in the range of 100mA to 1.5A is
available with a set point accuracy of better than ±20%. The
current-limit circuit prevents damage to the output MOSFET
and external load.
The nominal current-limit value is set with an external resistor
between ILIM and GND. For a desired current-limit, the value
of the external set resistor is given by:
Input and Output
IN is the power supply connection to the logic circuitry and the
drain of the output MOSFET. OUT is the source of the output
MOSFET. In a typical circuit, current flows from IN to OUT
toward the load. If VOUT is greater than VIN, current will flow
from OUT to IN since the switch is bidirectional when enabled. The output MOSFET and driver circuitry are also
designed to allow the MOSFET source to be externally forced
to a higher voltage than the drain (VOUT > VIN) when the
switch is disabled. In this situation, the MIC2544/48 avoids
undesirable current flow from OUT to IN. Both OUT pins must
be connected together.
Thermal Shutdown
 230V 
RSET = 

 ILIMIT 
where:
154Ω < RSET < 2.29kΩ
For example, to set a 1A nominal current-limit, RSET is
calculated as:
 230V 
 = 230Ω

 1A 
Thermal shutdown shuts off the output MOSFET and signals
the fault flag if the die temperature exceeds 140°C. 10°C of
hysteresis prevents the switch from turning on until the die
temperature drops to 130°C. Overtemperature detection
functions only when the switch is enabled.
The MIC2548 features an internal latch which causes the part
to remain off after thermal shutdown until a reset pulse is
provided via the enable pin (pin 1). While in current-limit, the
thermal shutdown latch prevents on/off cycling of the output.
Refer to Figure 2 for timing diagram. The flag remains low
until reset.
Current through RSET increases with OUT current. The
voltage across RSET could be monitored with a high impedance comparator to provide an indication of output current.
RSET should be between 154Ω ±0.5% and 2.29kΩ ±0.5%.
Short-Circuit Protection
In the event of a short-circuit, the output current will fold back
to approximately 80% of the short-circuit current-limit.
Fault Flag
FLG is an N-channel, open-drain MOSFET output. The faultflag is active (low) for current-limit or thermal shutdown
conditions. The flag output MOSFET is capable of sinking a
10mA load to typically 100mV above ground.
Enable Input
EN must be driven logic high or logic low, or be pulled high or
low for a clearly defined input. Floating the input may cause
unpredictable operation. EN should not be allowed to go
negative with respect to GND, and VEN should be less than
or equal to VIN.
June 2000
9
MIC2544/2548
Micrel
MIC2544/2548
Tj = PD × θJA + TA
where:
Applications Information
Supply Filtering
Tj = junction temperature
A 0.1µF to 1µF bypass capacitor from IN to GND, located near
the MIC2544 and MIC2548, is strongly recommended to
control supply transients. Without a bypass capacitor, an
output short may cause sufficient ringing on the input (from
supply lead inductance) to damage internal control circuitry.
Input transients must not exceed the absolute maximum
supply voltage (VIN max = 6V) even for a short duration.
TA = ambient temperature
θJA = is the thermal resistance of the package
Transient Overcurrent Filter
The inrush current from the connection of a heavy capacitive
load may cause the fault flag to fall for 10µs to 200µs while the
switch is in a constant-current mode, charging the capacitance.
4.0V to 5.5V
Adding an optional series resistor-capacitor (RSET2) in parallel with RSET, as shown in Figure 4, allows the transient
current-limit to be set to a different value than steady state. A
typical USB hot-plug inrush is 2A to 3A for 10µs to 20µs. If
RSET is 435Ω (510mA), an RSET2 of 88Ω (2.5A) and CSET of
1µF (RC = 100µs) allows transient surge of 3A to pass for
100µs without tripping the overcurrent flag (FLG).
USB Power Distribution
The MIC2544 is ideal for meeting USB power distribution
requirements. Figure 4 depicts a USB Host application. RSET
should be set to a value providing a current-limit >500mA.
The accurate current-limit of the MIC2544 will reduce power
supply current requirements. Also, fast reaction to short
circuit faults prevent voltage droop in mobile PC applications.
MIC2548-1BM
1
On/Off
2
3
4
EN
OUT
FLG
IN
GND
OUT
ILIM
NC
Power
Output
8
7
6
5
RSET
0.1µF to 1µF
NOTE: MSOP PACKAGE OPTION USES PIN 5 FOR ILIM.
PIN 4 IS NOT CONNECTED (NC).
Figure 3. Supply Bypassing
Power Dissipation
The device's junction temperature depends on several factors such as the load, PCB layout, ambient temperature and
package type. Equations that can be used to calculate power
dissipation and junction temperature are found below.
Printed Circuit Board Hot-Plug
The MIC2544/48 are ideal inrush current-limiters suitable for
hot-plug applications. Due to the integrated charge pump,
the MIC2544/48 presents a high impedance when off and
slowly becomes a low impedance as it turns on. This “softstart” feature effectively isolates power supplies from highly
capacitive loads by reducing inrush current during hot-plug
events. Figure 5 shows how the MIC2544 may be used in a
hot-plug application.
Calculation of power dissipation can be accomplished by the
following equation:
PD = RDS(on) × (IOUT)2
To relate this to junction temperature, the following equation
can be used:
Ferrite
Bead
5V
(+)
1.5k 2%
4.7µF
(–)
VBUS
D+
10k
IN
D–
3.3V USB Controller
V+
OUT
GND
VBUS
100k
D+
MIC5203-3.3
LDO Regulator
1.0
µF
MIC2544-2BM
ON/OFF
OVERCURRENT
GND
EN
OUT
FLG
IN
GND
OUT
ILIM
NC
120µF
D–
GND
Downstream
USB
Port 1
4.75V min.
500mA max.
0.1µF
D+
D–
0.01µF
GND
RSET
RSET(2)
CSET
Bold lines indicate
0.1" wide, 1-oz. copper
high-current traces.
(optional)
NOTE: MSOP PACKAGE OPTION USES PIN 5 FOR ILIM.
PIN 4 IS NOT CONNECTED (NC).
Figure 4. USB Host Application
MIC2544/2548
10
June 2000
Micrel
MIC2544/2548
MIC2544-2BM
1
VCC
2
to "Hot"
Receptacle
0.1
µF
3
4
EN
OUT
FLG
IN
GND
OUT
ILIM
NC
8
7
Backend
Function
6
5
CBULK
0.1µF
GND
Adaptor Card
NOTE: MSOP PACKAGE OPTION USES PIN 5 FOR ILIM
AND PIN 4 IS NO CONNECT (NC).
Figure 5. Hot Plug Application
June 2000
11
MIC2544/2548
Micrel
MIC2544/2548
Package Information
0.026 (0.65)
MAX)
PIN 1
0.157 (3.99)
0.150 (3.81)
DIMENSIONS:
INCHES (MM)
0.020 (0.51)
0.013 (0.33)
0.050 (1.27)
TYP
0.064 (1.63)
0.045 (1.14)
45°
0.0098 (0.249)
0.0040 (0.102)
0°–8°
0.197 (5.0)
0.189 (4.8)
0.010 (0.25)
0.007 (0.18)
0.050 (1.27)
0.016 (0.40)
SEATING
PLANE
0.244 (6.20)
0.228 (5.79)
8-Pin SOP (M)
0.199 (5.05)
0.187 (4.74)
0.122 (3.10)
0.112 (2.84)
DIMENSIONS:
INCH (MM)
0.120 (3.05)
0.116 (2.95)
0.036 (0.90)
0.032 (0.81)
0.043 (1.09)
0.038 (0.97)
0.012 (0.30) R
0.012 (0.03)
0.0256 (0.65) TYP
0.008 (0.20)
0.004 (0.10)
5° MAX
0° MIN
0.007 (0.18)
0.005 (0.13)
0.012 (0.03) R
0.039 (0.99)
0.035 (0.89)
0.021 (0.53)
8-Pin MSOP (MM)
MICREL INC. 1849 FORTUNE DRIVE SAN JOSE, CA 95131 USA
TEL
+ 1 (408) 944-0800
FAX
+ 1 (408) 944-0970
WEB
http://www.micrel.com
This information is believed to be accurate and reliable, however no responsibility is assumed by Micrel for its use nor for any infringement of patents or
other rights of third parties resulting from its use. No license is granted by implication or otherwise under any patent or patent right of Micrel Inc.
© 2000 Micrel Incorporated
MIC2544/2548
12
June 2000