MICREL MIC2549A-2BN, MIC2549A-2BTS, MIC2545A-2BTS, MIC2549A-1BM, MIC2549A-1BN Datasheet
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MIC2545A/2549A Micrel
MIC2545A/2549A
Programmable Current Limit High-Side Switch
Preliminary Information
General Description
The MIC2545A and MIC2549A 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 MIC2545A/
49A 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 adjustable current-limit, protects the switch and the attached device.
The MIC2545A/49A’s open-drain flag output is used to indicate current-limiting or thermal shutdown to a local controller.
The MIC2549A 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 MIC2549A.
The MIC2545A and MIC2549A are available in active-high
and active-low enable versions in 8-pin DIP, SOIC, and
TSSOP packages.
Features
• 2.7V to 5.5V input
• Adjustable current-limit up to 3A
• Reverse current flow blocking
• 90µA typical on-state supply current
• 1µA typical off-state supply current
• 50mΩ maximum on-resistance
• Open-drain fault flag
• Thermal shutdown
• Thermal shutdown output latch (MIC2549A)
• 2ms (slow) soft-start turn-on, fast turnoff
• Available with active-high or active-low enable
Applications
• USB power distribution
• PCI Bus Power Switching
• Notebook PC
• ACPI power distribution
• PC card hot swap applications
• Inrush current-limiting
Typical Application
+5V
R
SET
MIC2545A
EN
FLG
GND
ILIM
OUT
IN
OUT
IN
0.1µF
Peripheral
33µF
10k
On/Off
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 MIC2545A/2549A
MIC2545A/2549A Micrel
Ordering Information
Part Number Enable Latch* Temperature Range Package
MIC2545A-1BM Active High –40°C to +85°C 8-lead SOP
MIC2545A-1BN Active High –40°C to +85°C 8-pin DIP
MIC2545A-1BTS Active High –40°C to +85°C 14-lead TSSOP
MIC2545A-2BM Active Low –40°C to +85°C 8-lead SOP
MIC2545A-2BN Active Low –40°C to +85°C 8-pin DIP
MIC2545A-2BTS Active Low –40°C to +85°C 14-lead TSSOP
MIC2549A-1BM Active High •–40°C to +85°C 8-lead SOP
MIC2549A-1BN Active High •–40°C to +85°C 8-pin DIP
MIC2549A-1BTS Active High •–40°C to +85°C 14-lead TSSOP
MIC2549A-2BM Active Low •–40°C to +85°C 8-lead SOP
MIC2549A-2BN Active Low •–40°C to +85°C 8-pin DIP
MIC2549A-2BTS Active Low •–40°C to +85°C 14-lead TSSOP
Pin Configuration
EN
FLG
GND
ILIM
(EN) 1
(FLG) 2
MIC2545A/2549A
1
2
3
4
8-Lead SOP (M)
8-Pin DIP (N)
MIC2545A/2549A
LOGIC,
CHARGE
PUMP
3 (GND)(ILIM) 4
OUT
8
IN
7
OUT
6
IN
5
6,8 (OUT)
5,7 (IN)
NC
FLG
GND
ILIM
MIC2545A/2549A
1EN OUT
2
3
4NC
5
6NC
7
14
13
12
11
10
9
8
14-Lead TSSOP (TS)
Pin Description
Pin Number Pin Number Pin Name Pin Function
SOP, DIP TSSOP
1 1 EN Enable (Input): Logic-compatible enable input (-1 version is active high, -2
version is active low). High input >1.8V typical; low input <1.4V typical.
Do not float.
MIC2549A only: Also resets thermal shutdown latch.
2 3 FLG Fault Flag (Output): Active-low, open-drain output. Indicates overcurrent or
thermal shutdown.
MIC2549A only: latched low on thermal shutdown.
3 5 GND Ground: Supply return.
4 7 ILIM Current Limit: Sets current limit threshold using an external resistor (R
connected to ground. 76.8Ω < R
5, 7 8, 12 IN Supply Input: Output MOSFET drain. Also powers internal circuitry. Both IN
pins must be externally connected together.
6, 8 10, 14 OUT Switch Output: Output MOSFET source. Both OUT pins must be externally
connected together.
2,4,6,9,11,13 NC not internally connected
SET
< 459Ω.
NC
IN
NC
OUT
NC
IN
SET
)
MIC2545A/2549A 2 June 2000
MIC2545A/2549A Micrel
Absolute Maximum Ratings (Note 1)
Supply Voltage (V
Output Voltage (V
Output Current (I
Enable Input (VEN) ......................................... –0.3V to +6V
Fault Flag Voltage (V
Fault Flag Current (I
Storage Temperature (TS) ....................... –65°C to +150°C
Junction Temperature (T
) ..................................................+6.0V
IN
) ...............................................+6.0V
OUT
)...............................Internally Limited
OUT
)...........................................+6.0V
FLG
) ............................................50mA
FLG
) .......................Internally Limited
J
Operating Ratings (Note 2)
Supply Voltage (V
Ambient Temperature Range (T
Package Thermal Resistance
PDIP (θ
) .........................................................130°C/W
JA
SOIC (θJA).........................................................160°C/W
TSSOP (θJA), Note 6 ........................................100°C/W
Current Limit Set Range, Note 5........................ 0.5A to 3A
) ................................... +2.7V to +5.5V
IN
) .............–40°C to +85°C
A
Lead Temperature (soldering 5 sec.) ........................ 260°C
ESD Rating, Note 3 ..................................................2000V
Electrical Characteristics
VIN = +5V; TA = 25°C, bold indicates –40°C to +85°C; unless noted
Symbol Parameter Condition Min Typ Max Units
Supply Current Switch off, OUT = open, Note 4 0.75 5 µA
Switch on, OUT = open, Note 4 90 125 µA
150 µA
V
EN
R
DS(on)
t
ON
t
R
t
OFF
t
F
t
SU
V
OL
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 MIC2545A-1 and MIC2549A-1. Off is ≥ 2.4V and on is ≤ 0.8V for the MIC2545A-2 and MIC2549A-2.
Note 5. Current limit is determined by:
Note 6. Assumes 4 layer PCB is used.
Note 7. Guaranteed by design but not production tested.
Enable Input Voltage Enable high transition, Note 4 2.4 1.6 V
Enable low transition, Note 1 1.5 0.8 V
Enable Input Current VEN = V
VEN = V
= 2.4V 0.01 1 µA
OH(min)
= 0.8V 0.01 1 µA
OL(max)
Enable Input Capacitance Note 7 1pF
Switch Resistance I
Current Limit Factor I
Output Leakage Current Switch off, V
= 500mA 35 50 mΩ
OUT
= 0.5A to 3A, V
LIMIT
I
= 1A to 2.5A, V
LIMIT
= 0V 1 10 µA
OUT
= 1V to 4V, Note 5 160 230 300 V
OUT
= 1V to 4V, Note 5 184 230 276 V
OUT
Output Turn-On Delay RL = 10Ω, CL = 1µF, Figures 1a, 1b 125ms
Output Turn-On Rise Time RL = 10Ω, CL = 1µF, Figure 1a, 1b 0.75 1.8 4.9 ms
Output Turnoff Delay RL = 10Ω, CL = 1µF, Figure 1a, 1b 25 µs
Output Turnoff Fall Time RL = 10Ω, CL = 1µF, Figure 1a, 1b 23 µs
Overtemperature Threshold TJ increasing 135 °C
Shutdown
Error Flag Off Current V
TJ decreasing 120 °C
= 5V 0.01 1 µA
FLG
EN Pulse Reset Width MIC2549A thermal shutdown latch, Note 7 1 µs
VIN to EN Set-Up MIC2549A, Note 7, Figure 1c 0 µs
Current-Limit Response Time V
Error Flag Output Resistance I
The enable input has about 100mV of hysteresis.
LIMIT
230
=
, where R
R
SET
I
= 0V to I
OUT
= 10mA 4 15 Ω
FLG
is in ohms, and 230 is typical current limit factor in volts.
SET
OUT
= 2A, I
= 1A, Note 7 40 µs
SET
June 2000 3 MIC2545A/2549A
MIC2545A/2549A Micrel
Test Circuit
V
OUT
Device
Under
Test
OUT
I
OUT
C
R
L
L
Timing Diagrams
t
r
V
OUT
90%
10%
90%
10%
t
f
Functional Characteristics Test Circuit
V
EN
V
OUT
50%
t
OFF
t
ON
90%
10%
Figure 1a. MIC2545A/49A-2
V
EN
V
OUT
50%
t
OFF
t
ON
90%
10%
Figure 1b. MIC2545A/49A-1
V
IN
t
SU
V
EN
Figure 1c. Input-to-Enable Setup Timing
MIC2545A/2549A 4 June 2000
MIC2545A/2549A Micrel
O
utput Reset
V
I
LIMIT
V
I
LIMIT
I
FLG
Short-Circuit Fault
Fault Removed
OUT
I
OUT
EN
I
DC
Thermal Shutdown
Reached
FLG
Figure 2a. MIC2549A-2 Timing: Output Is Reset By Toggling EN
Short-Circuit
EN
OUT
I
DC
OUT
Thermal Shutdown
Reached
Fault
Fault
Removed
Figure 2b. MIC2545A-2 Timing
June 2000 5 MIC2545A/2549A
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