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MIC2546/2547
Micrel
MIC2546/2547
Dual Programmable Current Limit Switch Preliminary Information
General Description
The MIC2546 and MIC2547 are integrated high-side dual power switches optimized for low loss dc power switching and other power management applications, including Advanced Configuration and Power Interface (ACPI). The MIC2546/47 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 MIC2546/47's open-drain flag outputs are used to indicate current-limiting or thermal shutdown to a local controller. The MIC2547 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 MIC2547. The MIC2546 and MIC2547 are available in active-high and active-low enable versions in 16-pin TSSOP and SOP packages.
Features
* * * * * * * * * * * * * * * * * * 2.7V to 5.5V input Adjustable current-limit up to 1.5A Reverse current flow blocking (no "body diode") 100A typical on-state supply current per channel 2A typical off-state supply current 120m maximum on-resistance Open-drain fault flag Thermal shutdown Thermal shutdown output latch (MIC2547) 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 Ideal for dual supply applications
Applications
Typical Application
+5V 0.1F
RFLGA
MIC2546-xBM On/Off ENA FLGA GNDA OUTA INA OUTA NC OUTB INB OUTB NC 33F Peripheral 33F Peripheral
RSETA
ILIMA On/Off ENB FLGB
RFLGB
GNDB ILIMB
RSETB
+3.3V 0.1F
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
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Ordering Information
Part Number MIC2546-1BM MIC2546-1BTS MIC2546-2BM MIC2546-2BTS MIC2547-1BM MIC2547-1BTS MIC2547-2BM MIC2547-2BTS 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 16-pin SOP 16-pin TSSOP 16-pin SOP 16-pin TSSOP 16-pin SOP 16-pin TSSOP 16-pin SOP 16-pin TSSOP
* Thermal Shutdown Latch
Pin Configuration
MIC2546/2547 INA 1 OUTA 2 ENA 3 NC 4 FLGA 5 GNDB 6 ILIMB 7 OUTB 8 16 OUTA 15 ILIMA 14 GNDA 13 FLGB 12 ENB 11 OUTB 10 NC 9 INB
(ILIMB) (GND) (ENA) (FLGA) (ILIMA) (ENB) (FLGB)
LOGIC, CHARGE PUMP
MIC2546/2547
LOGIC, CHARGE PUMP
(OUTA) (INA) (OUTB) (INB)
Functional Pinout
16-Pin SOP (M) 16-Pin TSSOP (TS)
Pin Description
Pin Number 1 2, 16 3 Pin Name INA OUTA ENA Pin Function Input A: Output A MOSFET drain. Also supplies internal circuitry. Switch A (Output): Output A MOSFET source. Pins 2 and 16 must be externally connected. Enable A (Input): Logic-compatible enable input. Active-high (-1) or activelow (-2). High input >1.7V typical; low input <1.5V typical. Do not float. MIC2547 only: Also resets thermal shutdown latch. Not internally connected. Fault Flag A (Output): Active-low, open-drain output. Indicates overcurrent or thermal shutdown conditions. MIC2547 only: latched low on thermal shutdown. Ground. Both pins must be connected to GND. Current Limit Channel B: Sets current-limit threshold using an external resistor, RSET, connected to ground. 154 < RSET < 2.29k. Switch B (Output): Pins 8 and 11 must be externally connected. Input B Enable B (Input) Fault Flag B (Output) Current Limit Channel A.
4, 10 5
NC FLGA
6, 14 7 8, 11 9 12 13 15
GNDB, GNDA ILIMB OUTB INB ENB FLGB ILIMA
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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 ..................................... 0.1 to 1.5A Ambient Temperature Range (TA) ............. -40C to +85C Package Thermal Resistance SOP (JA) .......................................................... 120C/W TSSOP (JA) ..................................................... 100C/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 4 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 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 Note 5 IOUT = 500mA IOUT = 100mA to 1.5A, VOUT = 1.0V to 4.0V, Note 6 Switch off RL = 10, CL = 1F, Figure 1a and 1b RL = 10, CL = 1F, Figure 1a and 1b RL = 10, CL = 1F, Figure 1a and 1b RL = 10, CL = 1F, Figure 1a and 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 FLG Response Time
Note 1. Note 2. Note 3. Note 4. Note 5. Note 6.
Min
Typ 1.5 200
Max 10 320
Units A A V
2.4
1.7 1.5 .01 .01 1 80 120 276 10 5 5 0.8 1 1
V A A pF m V A ms ms s s C C A s s s s
184
230 1
1 1
2 2 22 21 140 130 4 5 0.01
15 20 1
VFLG = 5V MIC2547 Thermal Shutdown Latch MIC2547, Note 5 VOUT = 0V 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 MIC2546-1 and MIC2547-1. Off is 2.4V and on is 0.8V for the MIC2546-2 and MIC2547-2. The enable input has about 200mV of hysteresis. Guaranteed by design, but not production tested. Current limit threshold is determined by: ILIMIT
=
230V RSET , where RSET is in ohms.
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Typical Characteristics
Output On-Resistance vs. Supply Voltage
120 SUPPLY CURRENT (mA) ON-RESISTANCE (m)
100 ON-RESISTANCE (m) 90 80
Output On-Resistance vs. Temperature
280 240 200 160 120 80 40
On-State Supply Current vs. Supply Voltage
100 3.3V 80
2.7V
TA = 27C
TA = 27C 70 60 50 2.5
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
280 SUPPLY CURRENT (A) SUPPLY CURRENT (A) 240 200 160 120 5.0V 80 40 2.7V 3.3V 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1
Off-State Supply Current vs. Temperature
0.20 SUPPLY CURRENT (A) RL = 44 0.18 0.16 0.14 0.12 0.1 0.08 0.06 0.04 0.02
Off-State Supply Current vs. Supply Voltage
TA = 27C
5.0V 3.3V
2.7V
0 -40 -20 0 20 40 60 80 100 TEMPERATURE (C)
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
2.0 ENABLE THRESHOLD (V) 1.9 1.8 1.7 1.6 1.5 1.4 1.3 1.2
Enable Threshold Voltage vs. Supply Voltage
2.0 ENABLE THRESHOLD (V) TA = 27C VEN RISING
Enable Threshold Voltage vs. Temperature
7 OUTPUT RISE TIME (ms) 6 5 4 3
Rise Time vs. Temperature
1.8 VEN RISING 1.6 1.4 1.2 1.0 -40 -20 0 20 40 60 80 100 TEMPERATURE (C) VEN FALLING
2.7V 3.3V
VEN FALLING
5.0V 2 1 RL = 44
1.1 1.0 2.5
3.0 3.5 4.0 4.5 5.0 SUPPLY VOLTAGE (V)
5.5
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)
2000
Output Current vs. Output Voltage
RSET = 150
VIN = 5V 1500
1500 VIN = 5V 1000 RSET = 470 500 RSET = 2.3k 0 0 1 2 3 4 5 OUTPUT VOLTAGE (V) 6
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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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 MIC2546-1 TIME (500s/div.)
IOUT (200mA/div.)
MIC2546-1 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
MIC2546-1 TIME (100ms/div.)
MIC2546-1 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 MIC2546-1
MIC2547-1 TIME (500s/div.)
TIME (500s/div.)
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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. MIC2546/47-1
VEN
50% tOFF tON
VOUT
90% 10%
Figure 1b. MIC2546/47-2
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Output Reset
EN VOUT ILIMIT IDC IOUT FLG
Short-Circuit Fault
Fault Removed Thermal Shutdown Reached
Figure 2a. MIC2547-2 Timing: Output is reset by toggling EN
EN VOUT ILIMIT IDC IOUT FLG
Short-Circuit Fault Fault Removed
Thermal Shutdown Reached
Figure 2b. MIC2546-2 Timing
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Block Diagram
ENA THERMAL SHUTDOWN 1.2V REFERENCE
OSC.
INA
CHARGE PUMP GATE CONTROL
CURRENT LIMIT
ILIMA RSETA
RESET
THERMAL SHUTDOWN LATCH (MIC2547)
OUTA FLGA
ENB THERMAL SHUTDOWN 1.2V REFERENCE
OSC.
INB
CHARGE PUMP GATE CONTROL
CURRENT LIMIT
ILIMB RSETB
RESET
THERMAL SHUTDOWN LATCH (MIC2547)
OUTB FLGB
GNDB
GNDA
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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 ILIMX and GND. For a desired current-limit, the value of the external set resistor is given by:
230V RSETX = ILIMITX
Functional Description
The MIC2546 and MIC2547 are dual 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 INX is the power supply connection to the logic circuitry and the drain of the output MOSFET. OUTX is the source of the output MOSFET. In a typical circuit, current flows from INX to OUTX toward the load. If VOUT is greater than VIN, current will flow from OUTX to INX 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 MIC2546/47 avoids undesirable current flow from OUTX to INX. Both OUT pins for a given channel 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 MIC2547 features an internal latch which causes the part to remain off after thermal shutdown until a reset pulse is provided via the enable pin. 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 ENX 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. ENX should not be allowed to go negative with respect to GND, and VENX should be less than or equal to VINX.
where: 154 < RSET < 2.29k For example, to set a 1A nominal current-limit, RSET is calculated as: 230V 1A
= 230
Current through RSETX increases with OUT current. The voltage across RSETX could be monitored with a high impedance comparator to provide an indication of output current. RSETX should be between 154 and 2.29k (0.5% resistor value). 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 FLGX is an N-channel, open-drain MOSFET output. The fault-flag 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.
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PD = RDS(on) x (IOUT)2 To relate this to junction temperature, the following equation can be used: 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 3, 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 MIC2546 is ideal for meeting USB power distribution requirements. Figure 3 depicts a USB Host application. RSET should be set to a value providing a current-limit >500mA. The accurate current-limit of the MIC2546 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 MIC2546/47 are ideal inrush current-limiters suitable for hot-plug applications. Due to the integrated charge pump, the MIC2546/47 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.
Applications Information
Supply Filtering A 0.1F to 1F bypass capacitor from INX to GND, located near the MIC2546 and MIC2547, 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
MIC2546-1BM
1
0.1 to 1F
2 3 4 5 6 7 8
INA OUTA ENA NC FLGA
OUTA ILIMA GNDA FLGB ENB
16 15 14 13 12 11 10 9 .
GNDB OUTB ILIMB OUTB NC INB
RSETA
RSETB
0.1 to 1F
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:
(+) (-)
5V 4.7F 1.5k 2% MIC5203-3.3 LDO Regulator 10k 10k 100k 3.3V USB Controller V+ ON/OFF MIC2546-2BM INA ENA NC FLGA D+ D- GND OUTA GNDA FLGB ENB NC INB 120F VBUS D+ 0.01F D- GND Ferrite Bead Downstream USB Port 2 4.75V min. 500mA max. Ferrite Bead VBUS OUTA ILIMA 100k
VBUS D+
D- GND
IN
OUT GND
RSET
0.01F 120F
D+ D- GND
OVERCURRENT
Downstream USB Port 1 4.75V min. 500mA max.
RSET
GNDB OUTB ILIMB OUTB
Bold lines indicate 0.1" wide, 1-oz. copper high-current traces.
RSET(2) CSET
(optional)
Figure 3. USB Host Application
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Package Information
PIN 1
0.157 (3.99) 0.150 (3.81)
DIMENSIONS: INCHES (MM)
0.020 (0.51) REF 0.050 (1.27) BSC
0.020 (0.51) 0.013 (0.33) 0.0098 (0.249) 0.0040 (0.102)
45 0-8 0.050 (1.27) 0.016 (0.40) 0.244 (6.20) 0.228 (5.79)
0.0648 (1.646) 0.0434 (1.102)
0.394 (10.00) 0.386 (9.80)
SEATING PLANE
16-Pin SOP (M)
4.50 (0.177) 6.4 BSC (0.252) 4.30 (0.169)
DIMENSIONS: MM (INCH)
0.30 (0.012) 0.19 (0.007) 7.90 (0.311) 7.70 (0.303)
1.10 MAX (0.043)
0.20 (0.008) 0.09 (0.003)
0.65 BSC (0.026)
0.15 (0.006) 0.05 (0.002)
8 0
1.00 (0.039) REF 0.70 (0.028) 0.50 (0.020)
16-Pin TSSOP (TS)
MICREL INC. 1849 FORTUNE DRIVE SAN JOSE, CA 95131
TEL
USA
+ 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
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