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MIC2544/2548
Micrel
MIC2544/2548
Programmable Current Limit High-Side Switch Preliminary Information
General Description
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. 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).
Features
* * * * * * * * * * * * * * * * * 2.7V to 5.5V input Adjustable current-limit up to 1.5A Reverse current flow blocking (no "body diode") 75A typical on-state supply current 1A typical off-state supply current 120m 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 USB power distribution PCI Bus Power Switching Notebook PC ACPI power distribution PC card hot swap applications Inrush current-limiting
Applications
Typical Application
+5V RFLG On/Off MIC2544-xBM EN FLG GND ILIM RSET OUT IN OUT NC 0.1F 33F Peripheral
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
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MIC2544/2548
MIC2544/2548
Micrel
Ordering Information
Part Number MIC2544-1BM MIC2544-1BMM MIC2544-2BM MIC2544-2BMM MIC2548-1BM MIC2548-1BMM MIC2548-2BM MIC2548-2BMM Enable Active High Active High Active Low Active Low Active High Active High Active Low Active Low * * * * Latch* Temperature Range -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C Package 8-pin SOP 8-pin MSOP 8-pin SOP 8-pin MSOP 8-pin SOP 8-pin MSOP 8-pin SOP 8-pin MSOP
* Thermal Shutdown Latch
Pin Configuration
MIC2544/2548
EN FLG GND ILIM 1 2 3 4 8 7 6 5 OUT IN OUT NC EN FLG GND NC 1 2 3 4
MIC2544/2548
8 7 6 5 OUT IN OUT ILIM
8-Pin SOP (M)
MIC2544/2548 (OUT) (EN) (FLG)
LOGIC, CHARGE PUMP
8-Pin MSOP (MM)
NOTE: PINS 4 AND 5 FOR SOIC AND MSOP ARE DIFFERENT.
(IN) (ILIM) (GND)
Pin Description
Pin Number MSOP-8 1 Pin Number SOP-8 1 Pin Name EN Pin Function 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. Fault Flag (Output): Active-low, open-drain output. Indicates overcurrent or thermal shutdown conditions. MIC2548 only: latched low on thermal shutdown. Ground Current Limit: Sets current-limit threshold using an external resistor, RSET, connected to ground. 154 < RSET < 2.29k. 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
2
FLG
3 5 7 6,8 4
3 4 7 6,8 5
GND ILIM IN OUT NC
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MIC2544/2548
Micrel
Absolute Maximum Ratings (Note 1)
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) ....................... -65C to +150C Junction Temperature (TJ) ....................... Internally Limited Lead Temperature (soldering 5 sec.) ........................ 260C ESD Rating, Note 3 ...................................................... 2kV
Operating Ratings (Note 2)
Supply Voltage (VIN) ................................... +2.7V to +5.5V Current Limit Set Range .................................. 0.1A to 1.5A Ambient Temperature Range (TA) ............. -40C to +85C Package Thermal Resistance SOP (JA) .......................................................... 160C/W MSOP (JA) ....................................................... 206C/W
Electrical Characteristics
VIN = +5V; TA = 25C, bold indicates -40C to +85C; unless noted Symbol Parameter Supply Current Condition switch off, OUT = open, Note 4 switch on, OUT = open, Note 4 VEN Enable Input Voltage enable high, Note 4 enable low, Note 1 Enable Input Current VEN = VOH(min) = 2.4V VEN = VOL(max) = 0.8V Enable Input Capacitance RDS(on) Switch Resistance Current Limit Factor Note 6 IOUT = 500mA IOUT = 100mA to 1A, VOUT = 1V to 4V, Note 5 IOUT = 500mA to 1.5A, VOUT = 1V to 4V, Note 5 Output Leakage Current tON tR tOFF tF Output Turn-On Delay Output Turn-On Rise Time Output Turnoff Delay Output Turnoff Fall Time Overtemperature Threshold Shutdown Error Flag Output Resistance switch off RL = 10, CL = 1F, Figures 1a, 1b RL = 10, CL = 1F, Figures 1a, 1b RL = 10, CL = 1F, Figures 1a, 1b RL = 10, CL = 1F, Figures 1a, 1b TJ increasing TJ decreasing VIN = 5V, IL = 10A VIN = 3.3V, IL = 10A Error Flag Off Current EN Pulse Reset Width VIN to EN Set-Up Current-Limit Response Time Overcurrent Flag Response Time
Note 1. Note 2. Note 3. Note 4.
Min
Typ 0.75 75
Max 5 160
Units A A V
2.4
1.7 1.5 0.01 0.01 1 80 120 276 299 10 5 5 0.8 1 1
V A A pF m V V A ms ms s s C C A s s s s
184 161
230 230 1
1 1
2 2 22 21 140 130 4 5 0.01
15 20 1
VFLG = 5V MIC2548 thermal shutdown latch MIC2548, Note 6 VOUT = 0V, Note 6 VOUT = VIN/2 to FLG low 5 0
25 5
Exceeding the absolute maximum rating may damage the device. The device is not guaranteed to function outside its operating rating. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF. 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.
230V Current limit threshold is determined by ILIMIT = R , where RSET is in ohms. SET
Note 5. Note 6.
Guaranteed by design but not production tested.
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MIC2544/2548
MIC2544/2548
Micrel
Test Circuit
VOUT Device Under OUT Test IOUT RL CL
tr VOUT 10% 90% 90% 10%
tf
Functional Characteristics Test Circuit
Timing Diagrams
50% tOFF tON VOUT 90% 10%
VEN
Figure 1a. MIC2544/48-1
VEN
50% tOFF tON
VOUT
90% 10%
Figure 1b. MIC2544/48-2
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Output Reset
EN VOUT ILIMIT IDC IOUT FLG
Short-Circuit Fault
Fault Removed Thermal Shutdown Reached
Figure 2a. MIC2548-2 Timing: Output is reset by toggling EN
EN VOUT ILIMIT IDC IOUT FLG
Short-Circuit Fault Fault Removed
Thermal Shutdown Reached
Figure 2b. MIC2544-2 Timing
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MIC2544/2548
Micrel
Typical Characteristics
Output On-Resistance vs. Supply Voltage
100 ON-RESISTANCE (m) 90 80 TA = 27C 70 60 50 2.5 ON-RESISTANCE (m) 120 SUPPLY CURRENT (mA)
Output On-Resistance vs. Temperature
140 120 100 80 60 40 20
On-State Supply Current vs. Supply Voltage
100 3.3V 80
2.7V
TA = 27C
5.0V 60
3.0 3.5 4.0 4.5 5.0 SUPPLY VOLTAGE (V)
5.5
40 -40 -20 0 20 40 60 80 100 TEMPERATURE (C)
0 2.5
3.0 3.5 4.0 4.5 5.0 SUPPLY VOLTAGE (V)
5.5
On-State Supply Current vs. Temperature
140 SUPPLY CURRENT (A) SUPPLY CURRENT (A) 120 100 80 60 40 20 0 -40 -20 0 20 40 60 80 100 TEMPERATURE (C) 2.7V 5.0V 3.3V 0.4
Off-State Supply Current vs. Temperature
0.10 SUPPLY CURRENT (A) RL = 44 0.3 5.0V 3.3V 0.1 2.7V 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01
Off-State Supply Current vs. Supply Voltage
TA = 27C
0.2
0 -40 -20 0 20 40 60 80 100 TEMPERATURE (C)
0 2.5
3.0 3.5 4.0 4.5 5.0 SUPPLY VOLTAGE (V)
5.5
Enable Threshold Voltage vs. Supply Voltage
2.0 ENABLE THRESHOLD (V) ENABLE THRESHOLD (V) 1.9 1.8 1.7 1.6 1.5 1.4 1.3 1.2 1.1 1.0 2.5 3.0 3.5 4.0 4.5 5.0 SUPPLY VOLTAGE (V) 5.5 VEN FALLING VEN RISING TA = 27C 2.0
Enable Threshold Voltage vs. Temperature
7 OUTPUT RISE TIME (ms) 6 5 4 3
Rise Time vs. Temperature
1.8 1.6 1.4 1.2
2.7V 3.3V
VEN RISING
VEN FALLING
5.0V 2 1 RL = 44
1.0 -40 -20 0 20 40 60 80 100 TEMPERATURE (C)
0 -40 -20 0 20 40 60 80 100 TEMPERATURE (C)
Output Fall Time vs. Temperature
2.5 OUTPUT FALL TIME (s) RL = 44 2.0 1.5 1.0 0.5 0 -40 -20 0 20 40 60 80 100 TEMPERATURE (C) 2.7V 3.3V 5.0V CURRENT LIMIT (mA)
2000
Current Limit vs. RSET
OUTPUT CURRENT (mA)
Output Current vs. Output Voltage
2000 RSET = 150 1500 VIN = 5V 1000 RSET = 470 500 RSET = 2.3k 0 0 1 2 3 4 5 OUTPUT VOLTAGE (V) 6
VIN = 5V 1500
1000
500 ISHORT 0 100
ISET
ITH
1000 RSET ()
5000
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Current Limit vs. Temperature
1100 OUTPUT CURRENT (mA) ITH 1000 900 800 700 ISHORT VIN = 5V RSET = 230 ISET CURRENT LIMIT (mA) 1000 900 800 700 600 2.5 1100
Current Limit vs. Supply Voltage
ITH ISET
TA = 27C RL = 230
ISHORT
600 -40 -20 0 20 40 60 80 100 TEMPERATURE (C)
3.0 3.5 4.0 4.5 5.0 SUPPLY VOLTAGE (V)
5.5
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MIC2544/2548
MIC2544/2548
Micrel
Functional Characteristics
VOUT VFLG VEN (2V/div.) (5V/div.) (10V/div.)
VFLG VEN (10V/div.) (5V/div.)
Turn-On Response
Turnoff Response
VOUT (2V/div.)
VIN = 5V CIN = 4.7F
CL = 1F RL = 10
IOUT (200mA/div.)
VIN = 5V CIN = 4.7F CL = 1F RL = 10 MIC2544-1 TIME (500s/div.)
IOUT (200mA/div.)
MIC2544-1 TIME (1ms/div.)
Current-Limit Response
VOUT VFLG VEN (5V/div.) (10V/div.) (10V/div.) VOUT VFLG VEN (5V/div.) (10V/div.) (10V/div.)
Enable Into Heavy Load
Thermal Shutdown
VIN = 5V CIN = 4.7F
ISET = 1A RL = 1
IOUT (500mA/div.)
IOUT (500mA/div.)
VIN = 5V CIN = 4.7F RL = 1
ISET = 1A
MIC2544-1 TIME (100ms/div.)
MIC2544-1 TIME (100ms/div.)
Enable Into Heavy Load
VFLG VEN (5V/div.) (10V/div.)
Inrush Current Response
VFLG VEN (5V/div.) (10V/div.)
VIN = 5V CIN = 4.7F RL = 1 ISET = 1A
Reset
VOUT (5V/div.)
VIN = 5V CIN = 4.7F RL = 10 CL = 110F
Output Latched
IOUT (500mA/div.)
Thermal Shutdown
IOUT (1A/div.)
CL = 60F
CL = 10F MIC2544-1
MIC2548-1 TIME (500s/div.)
TIME (500s/div.)
MIC2544/2548
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Block Diagram
EN THERMAL SHUTDOWN 1.2V REFERENCE
OSC.
IN
CHARGE PUMP GATE CONTROL
CURRENT LIMIT
ILIM RSET
RESET
THERMAL SHUTDOWN LATCH (MIC2548)
OUT FLG
GND
Functional Description
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. 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 Thermal shutdown shuts off the output MOSFET and signals the fault flag if the die temperature exceeds 140C. 10C of hysteresis prevents the switch from turning on until the die temperature drops to 130C. 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. 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 Adjustable Current-Limit 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:
230V RSET = ILIMIT
where: 154 < RSET < 2.29k For example, to set a 1A nominal current-limit, RSET is calculated as: 230V = 230 1A 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 154 0.5% and 2.29k 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.
MIC2544/2548
MIC2544/2548
Micrel
Tj = PD x JA + TA where: Tj = junction temperature TA = ambient temperature JA = 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 10s to 200s while the switch is in a constant-current mode, charging the capacitance. 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 10s to 20s. If RSET is 435 (510mA), an RSET2 of 88 (2.5A) and CSET of 1F (RC = 100s) allows transient surge of 3A to pass for 100s 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. 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.
Applications Information
Supply Filtering A 0.1F to 1F 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.
4.0V to 5.5V
MIC2548-1BM On/Off
1 2 3 4
EN FLG GND ILIM
OUT IN OUT NC
8 7 6 5
Power Output
RSET
0.1F to 1F
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. Calculation of power dissipation can be accomplished by the following equation: PD = RDS(on) x (IOUT)2 To relate this to junction temperature, the following equation can be used:
5V (+) 4.7F (-) VBUS D+ D- GND D+ D- Bold lines indicate 0.1" wide, 1-oz. copper high-current traces. GND RSET RSET(2) CSET (optional) 1.5k 2% MIC5203-3.3 LDO Regulator IN OUT GND 1.0 F 10k 3.3V USB Controller V+ ON/OFF OVERCURRENT 100k MIC2544-2BM EN FLG GND ILIM OUT IN OUT NC 0.1F 120F
Ferrite Bead VBUS D+ 0.01F D- GND Downstream USB Port 1 4.75V min. 500mA max.
NOTE: MSOP PACKAGE OPTION USES PIN 5 FOR ILIM. PIN 4 IS NOT CONNECTED (NC).
Figure 4. USB Host Application
MIC2544/2548
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MIC2544/2548
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MIC2544-2BM VCC 0.1 F
1 2
EN FLG GND ILIM
OUT IN OUT NC
8 7 6 5
to "Hot" Receptacle
3 4
Backend Function CBULK
GND
0.1F Adaptor Card
NOTE: MSOP PACKAGE OPTION USES PIN 5 FOR ILIM AND PIN 4 IS NO CONNECT (NC).
Figure 5. Hot Plug Application
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MIC2544/2548
MIC2544/2548
Micrel
Package Information
0.026 (0.65) MAX) PIN 1
0.157 (3.99) 0.150 (3.81)
DIMENSIONS: INCHES (MM)
0.050 (1.27) TYP
0.020 (0.51) 0.013 (0.33) 0.0098 (0.249) 0.0040 (0.102) 0-8 SEATING PLANE 45 0.010 (0.25) 0.007 (0.18)
0.064 (1.63) 0.045 (1.14)
0.197 (5.0) 0.189 (4.8)
0.050 (1.27) 0.016 (0.40) 0.244 (6.20) 0.228 (5.79)
8-Pin SOP (M)
0.122 (3.10) 0.112 (2.84)
0.199 (5.05) 0.187 (4.74)
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
0.007 (0.18) 0.005 (0.13)
0.012 (0.03) 0.0256 (0.65) TYP
0.008 (0.20) 0.004 (0.10)
5 MAX 0 MIN
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. (c) 2000 Micrel Incorporated
MIC2544/2548
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June 2000

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