MAX1558ETB-T [ROCHESTER]
2A 2 CHANNEL, BUF OR INV BASED PRPHL DRVR, DSO10, 3 X 3 MM, 0.80 MM HEIGHT, MO-229WEED-3, TDFN-10;
| 型号： | MAX1558ETB-T |
| 厂家： | 
Rochester Electronics |
| 描述： | 2A 2 CHANNEL, BUF OR INV BASED PRPHL DRVR, DSO10, 3 X 3 MM, 0.80 MM HEIGHT, MO-229WEED-3, TDFN-10 驱动 信息通信管理 接口集成电路 |
| 文件： | 总13页 (文件大小：935K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-3128; Rev 0; 6/04
Dual, 3mm x 3mm, 1.2A/Programmable-Current
USB Switches with Autoreset
General Description
Features
The MAX1558/MAX1558H are dual, current-limited
switches with autoreset for USB applications. Autoreset
latches the switch off if it is shorted for more than 20ms,
saving system power. The shorted output is then tested
to determine when the short is removed to automatically
restart the channel. Each channel delivers up to 1.2A
and meets all IEC specifications for USB ports. Low
quiescent supply current (45µA) and standby current
(3µA) conserve battery power in portable applications.
♦ 55mΩ Switch Resistance
♦ Tiny 10-Pin, 3mm x 3mm TDFN Package
♦ 14% Accurate Current Limit
♦ Autorestart when Fault is Removed
♦ Programmable Current Up to 1.2A
♦ Thermal-Overload Protection
The MAX1558/MAX1558H safety features ensure that the
USB port is protected. Built-in thermal-overload protection
limits power dissipation and junction temperature.
Accurate, programmable current-limiting circuitry pro-
tects the input supply against both overload and short-cir-
cuit conditions. 20ms fault blanking enables the circuit to
ignore transient faults, such as those caused when hot
swapping a capacitive load, preventing false alarms to
the host system. The MAX1558/MAX1558H also feature
reverse-current protection circuitry to block current flow
from the output to the input when the switches are off.
♦ Built-In 20ms Fault Blanking
♦ Compliant to All USB Specifications
♦ 2.7V to 5.5V Supply Range
♦ Independent-Output Fault Indicators
♦ Block Reverse Current when Disabled
♦ 15kV ESD Protection (with Capacitor)
♦ UL Listing Pending
The MAX1558/MAX1558H are available in space-sav-
ing 3mm x 3mm, 10-pin TDFN packages. The MAX1558
is enabled with an active-low signal, and the
MAX1558H is enabled with an active-high signal.
Ordering Information
PIN-
TOP
PART
TEMP RANGE
PACKAGE
MARK
10 TDFN
(3mm x 3mm)
MAX1558ETB
-40°C to +85°C
AAR
AAS
Applications
10 TDFN
(3mm x 3mm)
MAX1558HETB -40°C to +85°C
USB Ports and Hubs
Notebook Computers and Desktops
PDAs and Palmtop Computers
Docking Stations
Typical Operating Circuit
INA
INB
ONA
ONB
ONA
ONB
INPUT
2.7V TO 5.5V
Pin Configuration
USB
PORT A
OUTA
TOP VIEW
MAX1558
FLTA
1
2
3
4
5
INA
10 OUTA
USB
PORT B
OUTB
ONA (ONA)
9
8
7
6
FLTA
GND
MAX1558
(MAX1558H)
ISET
ONB (ONB)
INB
FLTB
ISET
FLTB
OUTB
GND
TDFN
3mm x 3mm
________________________________________________________________ Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
Dual, 3mm x 3mm, 1.2A/Programmable-Current
USB Switches with Autoreset
ABSOLUTE MAXIMUM RATINGS
IN_, ON_, OUT_, ISET, FLT_ to GND........................-0.3V to +6V
IN_ to OUT_ (when disabled) (Note 1)........................-6V to +6V
Continuous Power Dissipation (T = +70°C)
A
10-Pin TDFN 3mm x 3mm
(derate 24.4mW/°C above +70°C).............................1952mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature......................................................+160°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
IN_ to OUT_ (when enabled) (Note 2)............-1.6A to +1.6A
FLT_ Sink Current................................................................20mA
RMS
Note 1: Reverse current (current from OUT_ to IN_) is blocked when disabled.
Note 2: Forward current (current from IN_ to OUT_) is internally limited. Reverse current, from OUT_ to IN_, is not limited when the
device is enabled and must be kept below 1.5A
to prevent permanent device damage. When the MAX1558/MAX1558H
RMS
are disabled, the switch turns off and reverse current is internally blocked.
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(V
= V
= 5V, V
= V
= 0V (MAX1558), V
= V
= 5V (MAX1558H), R = 26kΩ to GND, T = 0°C to +85°C,
ISET A
INA
INB
ONA
ONB
ONA
ONB
unless otherwise noted. Typical values are at T = +25°C.) (Note 3)
A
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
5.50
75
UNITS
Supply Voltage Range
2.75
V
V
V
V
= 5V, T = +25°C
55
64
IN_
IN_
IN_
A
Switch On-Resistance
R
= 3.3V, T = +25°C
mΩ
ON
A
= 4.4V, T = 0°C to +85°C
105
6
A
Standby Supply Current
Quiescent Supply Current
Both switches disabled
Both switches enabled
3
µA
µA
45
75
10
V
V
= V
= V
= 0V
= 5V
0.03
0.03
OUTA
OUTA
OUTB
OUT_ Off-Leakage Current
Reverse Leakage Current
Switches disabled
= 0V, V
µA
µA
OUTB
V
= V = 5V, both
OUTB
IN_
OUTA
0.03
2.5
switches disabled
Undervoltage-Lockout Threshold
Continuous Load Current
V
Rising edge, 3% hysteresis
2.3
1.2
2.7
V
A
UVLO
R
= 26kΩ
ISET
R
ISET
R
ISET
R
ISET
R
ISET
R
ISET
R
ISET
R
ISET
R
ISET
R
ISET
= 26kΩ
= 39kΩ
= 60kΩ
= 26kΩ
= 39kΩ
= 60kΩ
= 26kΩ
= 39kΩ
= 60kΩ
1.20
0.80
0.50
1.45
1.4
0.925
0.6
1.60
1.05
0.70
2.60
V
0.5V
- V
=
IN_
OUT_
Current-Limit Threshold
A
2.0
V
(I
= 0V
pulsing)
OUT_
OUT_
Peak Short-Circuit Current Limit
RMS Short-Circuit Current Limit
I
I
1.40
0.90
0.55
0.37
0.23
A
(PEAK)
SHORT
SHORT
V
(I
= 0V
pulsing)
OUT_
OUT_
A
RMS
Short-Circuit Continuous Current-
Limit Transition Threshold
(Note 4)
From I
1
V
Fault-Blanking Timeout Period
condition to 50% of V
8
20
40
ms
LIMIT
FLT_
R
OUT_
= 10Ω, C
= 1µF, does not
OUT_
Turn-On Delay
t
include rise time (from ON asserted to
0.5
1.4
4.0
ms
ON
V
= 10% V
)
IN_
OUT_
2
_______________________________________________________________________________________
Dual, 3mm x 3mm, 1.2A/Programmable-Current
USB Switches with Autoreset
ELECTRICAL CHARACTERISTICS (continued)
(V
= V
= 5V, V
= V
= 0V (MAX1558), V
= V
= 5V (MAX1558H), R = 26kΩ to GND, T = 0°C to +85°C,
ISET A
INA
INB
ONA
ONB
ONA
ONB
unless otherwise noted. Typical values are at T = +25°C.) (Note 3)
A
PARAMETER
Output Rise Time
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
C
= 1µF, R
= 10Ω, (from 10% to
OUT_
OUT_
t
4
ms
RISE
90% of V
)
OUT_
R
OUT_
= 10Ω, C
= 1µF, does not
OUT_
include rise time (from ON deasserted to
Turn-Off Delay from ON
t
100
1000
µs
OFF
V
= 90% V
)
OUT_
IN_
C
= 1µF, R
= 10Ω (from 90% to
OUT_
OUT_
Output Fall Time
t
3
ms
°C
V
FALL
10% of V
)
OUT_
Thermal-Shutdown Threshold
10°C hysteresis
+160
V
V
V
V
V
= 2.7V to 4.0V
1.6
2.0
IN_
IN_
ONA/ONB Logic Input High
Voltage
V
IH
= 4.0V to 5.5V
= 2.7V to 4.0V
= 4.0V to 5.5V
0.6
0.8
+1
IN_
ONA/ONB Logic Input Low
Voltage
V
V
IL
IN_
Logic Input Current
= 0V or V
= 1mA
-1
µA
V
ON_
SINK
IN_
FLT_ Output Low Voltage
I
0.4
FLT_ Output High Leakage
Current
V
= V
= 5.5V
FLT_
1
µA
IN_
Autorestart Current
Autorestart Threshold
Autorestart Delay
In latched-off state, V
= 0V
> 1V
10
0.4
8
25
0.5
20
50
0.6
40
mA
V
OUT_
In latched-off state, rising
In latched-off state, V
ms
OUT_
ELECTRICAL CHARACTERISTICS
(V
= V
= 5V, V
= V
= 0V (MAX1558), V
= V
= 5V (MAX1558H), R = 26kΩ to GND, T = -40°C to +85°C,
ISET A
INA
INB
ONA
ONB
ONA
ONB
unless otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
5.5
75
UNITS
Supply Voltage Range
2.7
V
V
V
= 5V, T = +25°C
A
IN_
IN_
Switch On-Resistance
Standby Supply Current
R
mΩ
ON
= 4.4V, T = 0°C to +85°C
105
6
A
Both switches disabled
Both switches enabled
µA
µA
µA
V
Quiescent Supply Current
OUT_ Off-Leakage Current
75
Switches disabled, V
= V
= 0V
10
OUTA
OUTB
Undervoltage-Lockout Threshold
Continuous Load Current
V
Rising edge, 3% hysteresis
2.3
1.2
2.7
UVLO
R
= 26kΩ
A
ISET
R
ISET
R
ISET
R
ISET
= 26kΩ
= 39kΩ
= 60kΩ
1.20
0.80
0.50
1.60
1.05
0.70
Current-Limit Threshold
V
- V
= 0.5V
A
IN_
OUT_
V
(I
= 0V
pulsing)
OUT_
OUT_
Peak Short-Circuit Current Limit
Fault-Blanking Timeout Period
I
R
= 26kΩ
1.45
8
2.60
40
A
SHORT
ISET
(PEAK)
From I
condition to 50% of V
FLT_
ms
LIMIT
_______________________________________________________________________________________
3
Dual, 3mm x 3mm, 1.2A/Programmable-Current
USB Switches with Autoreset
ELECTRICAL CHARACTERISTICS (continued)
(V
= V
= 5V, V
= V
= 0V (MAX1558), V
= V
= 5V (MAX1558H), R = 26kΩ to GND, T = -40°C to +85°C,
ISET A
INA
INB
ONA
ONB
ONA
ONB
unless otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
= 10Ω, C = 1µF, does not
MIN
TYP
MAX
UNITS
R
OUT_
OUT_
include rise time (from ON asserted to
Turn-On Delay
t
0.5
4.0
ms
ON
V
= 10% V
)
OUT_
IN_
R
OUT_
= 10Ω, C
= 1µF, does not
OUT_
include rise time (from ON deasserted to
Turn-Off Delay from ON
t
1000
µs
OFF
V
V
V
V
V
V
= 90% V
)
IN_
OUT_
= 2.7V to 4.0V
= 4.0V to 5.5V
= 2.7V to 4.0V
= 4.0V to 5.5V
1.6
2.0
IN_
IN_
ONA/ONB Logic Input High
Voltage
V
V
V
IH
0.6
0.8
+1
IN_
ONA/ONB Logic Input Low
Voltage
V
IL
IN_
Logic Input Current
= 0V or V
= 1mA
-1
µA
V
ON_
SINK
IN_
FLT_ Output Low Voltage
I
0.4
FLT_ Output High Leakage
Current
V
= V
= 5.5V
FLT_
1
µA
IN_
Autorestart Current
Autorestart Threshold
Autorestart Delay
In latched-off state, V
= 0V
> 1V
10
0.4
8
50
0.6
40
mA
V
OUT_
In latched-off state, rising
In latched-off state, V
ms
OUT_
Note 3: Specifications from 0°C to -40°C are guaranteed by design but not 100% tested.
Note 4: The output voltage at which the device transitions from short-circuit current limit to continuous current limit. See the Output-
Current Fault Protection section.
Typical Operating Characteristics
(V
= V
= 5V, V
= V
= 0V (MAX1558), V
= V
= 5V (MAX1558H), R
= 26kΩ to GND. Typical values are at T =
INA
INB
ONA
ONB
ONA
ONB
ISET A
+25°C, unless otherwise noted.)
QUIESCENT SUPPLY CURRENT
vs. SUPPLY VOLTAGE
CURRENT-LIMIT PROGRAM vs. R
QUIESCENT CURRENT vs. TEMPERATURE
ISET
1.6
1.5
1.4
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
60
50
40
30
20
10
0
50
45
40
35
30
V
= 5.5V
IN_
V
= 5V
IN_
V
= 4.5V
IN_
24 28 32 36 40 44 48 52 56 60
(kΩ)
0
1
2
3
4
5
6
-40
-15
10
35
60
85
R
SUPPLY VOLTAGE (V)
TEMPERATURE (°C)
ISET
4
_______________________________________________________________________________________
Dual, 3mm x 3mm, 1.2A/Programmable-Current
USB Switches with Autoreset
Typical Operating Characteristics (continued)
(V
= V
= 5V, V
= V
= 0V (MAX1558), V
= V
= 5V (MAX1558H), R
= 26kΩ to GND. Typical values are at T
A
=
INA
INB
ONA
ONB
ONA
ONB
ISET
+25°C, unless otherwise noted.)
SWITCH OFF-LEAKAGE CURRENT
vs. TEMPERATURE
OFF REVERSE-BLOCKING LEAKAGE
CURRENT vs. OUTPUT VOLTAGE
SHUTDOWN CURRENT vs. TEMPERATURE
1000
100
10
100
10
1
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
ON_ = IN_ (MAX1558)
ON_ = GND
(MAX1558H)
ON_ = V (MAX1558)
IN_
ON_ = GND (MAX1558H)
1
0.1
0.01
0.1
-40
-15
10
35
60
85
0
1
2
3
4
5
6
-40
-40
-40
-15
10
35
60
85
85
85
TEMPERATURE (°C)
OUTPUT VOLTAGE (V)
TEMPERATURE (°C)
NORMALIZED ON-RESISTANCE
vs. TEMPERATURE
CONTINUOUS CURRENT-LIMIT THRESHOLD
vs. TEMPERATURE
TURN-ON TIME
vs. TEMPERATURE (t + t
)
ON RISE
1.45
1.44
1.43
1.42
1.41
1.40
1.39
1.38
1.37
1.36
1.35
1.50
1.25
1.00
0.75
0.50
8
7
6
5
4
3
V
= 4.5V
IN_
V
= 5.5V
IN_
V
= 5V
IN_
-40
-15
10
35
60
85
-15
10
35
60
-40
-15
10
35
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
TURN-OFF TIME
FAULT-BLANKING TIME
vs. TEMPERATURE
FAULT OUTPUT LOW VOLTAGE
vs. TEMPERATURE
vs. TEMPERATURE (t
+ t
)
OFF FALL
4.00
3.75
3.50
3.25
3.00
2.75
2.50
2.25
2.00
25
24
23
22
21
20
275
250
225
200
175
150
125
100
V
= 5.5V
IN_
V
= 4.5V
IN_
V
= 4.5V
IN_
V
= 5V
IN_
V
= 5V
IN_
V
= 5.5V
V
= 4.5V
IN_
IN_
V
= 5V
IN_
V
= 5.5V
5
IN_
-15
10
35
60
-40 -25 -10
20 35 50 65 80
-40
-15
10
35
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
_______________________________________________________________________________________
5
Dual, 3mm x 3mm, 1.2A/Programmable-Current
USB Switches with Autoreset
Typical Operating Characteristics (continued)
(V
= V
= 5V, V
= V
= 0V (MAX1558), V
= V
= 5V (MAX1558H), R
= 26kΩ to GND. Typical values are at T =
INA
INB
ONA
ONB
ONA
ONB
ISET A
+25°C, unless otherwise noted.)
AUTORESET CURRENT
vs. INPUT VOLTAGE
AUTORESET CURRENT
vs. TEMPERATURE
40
35
30
25
20
40
38
36
34
32
30
28
26
24
22
20
V
= 5.5V
IN_
T
= -40°C
A
V
= 5V
IN_
V
= 4.5V
IN_
T
= +85°C
A
T
= +25°C
A
3.0
3.5
4.0
4.5
(V)
5.0
5.5
6.0
-40
-15
10
35
60
85
V
TEMPERATURE (°C)
IN
SHORT-CIRCUIT RESPONSE INTO 0Ω
OVERLOAD RESPONSE INTO 2.5Ω
MAX1558/58H toc16
MAX1558/58H toc15
V
V
IN
5V
IN
5V/div
0
SWITCH ON
5V/div
0
SHORT
APPLIED
SHORT
REMOVED
OUT_
FLT_
V
OUT
5V/div
0
5V/div
0
AUTORESTART
5V/div
0
5A/div
0
FLTA_
I
OUT_
I
OUT_
1A/div
0
20ms/div
20ms/div
SWITCH TURN-ON TIME
SWITCH TURN-OFF TIME
MAX1558/58H toc17
MAX1558/58H toc18
2V/div
0
ON_
2V/div
ON_
0
2V/div
0
OUT_
2V/div
0
OUT_
2.0ms/div
1.0ms/div
6
_______________________________________________________________________________________
Dual, 3mm x 3mm, 1.2A/Programmable-Current
USB Switches with Autoreset
Pin Description
PIN
NAME
FUNCTION
Power Input for OUTA. Connect INA and INB together and bypass with a 0.1µF capacitor to ground.
Load conditions may require additional bulk capacitance to prevent the input from being pulled down.
1
INA
ONA
*(ONA)
Control Input for Switch A. Can be driven higher than IN_ without damage. A logic low turns switch A on
for the MAX1558. A logic high turns switch A on for the MAX1558H.
2
3
4
5
6
Current-Limit Adjust for Both Channels. Connect a resistor between 26kΩ to 60kΩ from ISET to ground to
program the current limit. See Setting the Current Limit in the Applications Information section.
ISET
ONB
*(ONB)
Control Input for Switch B. Can be driven higher than IN_ without damage. A logic low turns switch B on
for the MAX1558. A logic high turns switch B on for the MAX1558H.
Power Input for OUTB. Connect INB and INA together and bypass with a 0.1µF capacitor to ground.
Load conditions may require additional bulk capacitance to prevent the input from being pulled down.
INB
Power Output for Switch B. Connect a 1µF capacitor from OUTB to ground. The load condition may
require additional bulk capacitance.
OUTB
Fault Indicator Output for Switch B. This open-drain output goes low when switch B is in thermal
shutdown or UVLO or in a sustained (>20ms) current-limit or short-circuit condition.
7
8
9
FLTB
GND
FLTA
Ground
Fault Indicator Output for Switch A. This open-drain output goes low when switch A is in thermal
shutdown or UVLO or in a sustained (>20ms) current-limit or short-circuit condition.
Power Output for Switch A. Connect a 1µF capacitor from OUTA to ground. The load condition may
require additional bulk capacitance.
10
—
OUTA
PAD
Exposed Pad, Internally Connected to GND. Connect exposed pad to a large copper trace for maximum
power dissipation.
*( ) are for the MAX1558H only.
Detailed Description
The MAX1558/MAX1558H are dual current-limited
switches designed for USB applications. They have two
independent switches, each with its own enable control
input and autoreset function. Each switch has an error-
flag output to notify the USB controller when current-
limit, short-circuit, undervoltage-lockout, or thermal-
shutdown conditions occur (Figure 2). The MAX1558/
MAX1558H operate from a 2.7V to 5.5V supply. Each
output can supply up to 1.2A. Current limit for both
channels is set with one external resistor.
0.1µF
INA
INB
ONA
ONB
ONA
ONB
INPUT
2.7V TO 5.5V
USB
PORT A
OUTA
100kΩ
1µF*
1µF*
MAX1558
FLTA
USB
PORT B
OUTB
100kΩ
The MAX1558/MAX1558H have independent thermal
shutdown for each switch in the event of a prolonged
overload. An autoreset function monitors the output and
automatically turns the switch on when the overload is
removed. Separate current limiting and thermal-shut-
down circuits permit each switch to operate indepen-
dently, improving system robustness.
FLTB
ISET
GND
*USB APPLICATIONS MAY REQUIRE ADDITIONAL
BULK CAPACITANCE
Figure 1. Typical Application Circuit
_______________________________________________________________________________________
7
Dual, 3mm x 3mm, 1.2A/Programmable-Current
USB Switches with Autoreset
INA
FLTA
INA
ONA
ONA
CHARGE
PUMP
ILIMA
30mA
BIAS
UVLO
REF
OUTA
THERMAL
SHUTDOWN
GND
FAULT
LOGIC
30mA
ILIMB
OSC
25kHz
TIMER
20ms
OUTB
ONB
ONB
CHARGE
PUMP
INB
INB
0.6V
PROGRAM ILIMA
PROGRAM ILIMB
FLTB
MAX1558
ISET
Figure 2. Functional Diagram
8
_______________________________________________________________________________________
Dual, 3mm x 3mm, 1.2A/Programmable-Current
USB Switches with Autoreset
Undervoltage Lockout and
Input Voltage Requirements
Autoreset Mode
If an output fault is detected for more than the 20ms
blanking time, the output latches off and the FLT_ out-
put goes low. The MAX1558/MAX1558H then source
30mA to the faulted output and monitor the output volt-
age to determine when the overload is removed. If the
voltage on the output rises above 0.5V for more than
20ms, the fault resets and the output turns on. The
MAX1558 can also be reset from fault manually by tog-
gling ON_ (ON_ for the MAX1558H) for that channel.
The MAX1558/MAX1558H include a UVLO circuit to
prevent erroneous switch operation when the input volt-
age is low during startup and brownout conditions.
Operation is inhibited when V
is less than 2.5V.
IN_
Output-Current Fault Protection
The current limit for both switch outputs is programmed
by a resistor between 26kΩ and 60kΩ connected from
ISET to ground. See the Current-Limit Program Level vs.
R
ISET
curve in the Typical Operating Characteristics and
Reverse Current Blocking
The USB specification does not allow an output device
to source current back into the USB port. However, the
MAX1558/MAX1558H are designed to safely power
noncompliant devices. When disabled, each output is
switched to a high-impedance state, blocking reverse-
current flow from the output back to the input. However,
during normal operation with the device enabled, the
MAX1558/MAX1558H are bidirectional switches.
Setting the Current Limit in the Applications Information
section. The MAX1558 reduces the gate drive to the
MOSFET switch when the programmed current-limit value
is reached. If the current-limit program value is reached,
the part reduces gate drive to regulate at the current limit.
If the current limit persists for 20ms (typ), the output turns
off and the fault flag is set until the fault is removed, as
detected by the autoreset circuit.
When the the output drops below 1V (typ), the current
limit is set 30% above the programmed level and
pulsed. This lowers the RMS current for a short-circuit
condition, which reduces system load current and
power dissipation. If a short circuit persists for 20ms,
the output turns off and the fault flag is set. The autore-
set circuit automatically restarts the part if the fault is
removed.
Thermal Shutdown
The MAX1558/MAX1558H feature independent thermal
shutdown for each switch channel, allowing one switch
to deliver power even if the other switch has a fault con-
dition. When the junction temperature exceeds +160°C,
the switch turns off and the FLT_ output goes low imme-
diately; fault blanking does not occur during thermal
limit. When the junction cools by 10°C, the switch turns
on again. If the fault-overload condition continues, the
switch cycles on and off, resulting in a pulsed output,
saving battery power.
Fault Blanking
The MAX1558/MAX1558H switches can reach current
limit in normal operation when powering up or driving
heavy capacitive loads. To differentiate these conditions
from short circuits or sustained overloads, the
MAX1558/MAX1558H have independent fault-blanking
circuits in each switch. When a load transient causes
the device to enter the current limit, an internal counter
monitors the duration of the fault. For load faults exceed-
ing the 20ms fault-blanking time, the offending switch
turns off, the corresponding FLT_ signal asserts low,
and that channel enters autoreset mode (see the
Autoreset Mode section). Only current-limit and short-
circuit faults are blanked. Thermal-overload faults and
input-voltage drops below the UVLO threshold immedi-
ately cause the switch to turn off and FLT_ to assert low.
Fault Indicators
The MAX1558/MAX1558H provide an open-drain fault
output (FLT_) for each switch. For most applications, con-
nect FLT_ to IN_ through a 100kΩ pullup resistor. FLT_
goes low when any of the following conditions occur:
• The input voltage is below the UVLO threshold.
• The switch junction temperature exceeds the +160°C
thermal-shutdown temperature limit.
• The switch is in current-limit or short-circuit limit mode
after the 20ms fault-blanking period is exceeded.
• The switch is in autoreset mode.
After the fault condition is removed, the FLT_ output
deasserts after a 20ms delay. Ensure that the
MAX1558/MAX1558H have adequate input bypass
capacitance to prevent glitches from triggering FLT_ out-
puts. Glitches that cause the input supply to drop below
2.5V may cause the undervoltage lockout to trigger, turn-
ing the outputs off and asserting the FLT signals.
Fault blanking allows the MAX1558 to handle USB
loads that may not be fully compliant with USB specifi-
cations. USB loads with additional bypass capacitance
and/or large startup currents can be successfully pow-
ered even while protecting the upstream power source.
No fault is indicated if the switch is able to bring up the
load within the 20ms blanking period.
_______________________________________________________________________________________
9
Dual, 3mm x 3mm, 1.2A/Programmable-Current
USB Switches with Autoreset
Driving Inductive Loads
A wide variety of devices (mice, keyboards, cameras,
Applications Information
Setting the Current Limit
A resistor from ISET to ground programs the current-
limit value for both outputs. Use a resistor between
26kΩ and 86kΩ to set the current limit according to
the formula:
and printers) can load the USB port. These devices com-
monly connect to the port with cables, which can add an
inductive component to the load. This inductance caus-
es the output voltage at the USB port to ring during a
load step. The MAX1558/MAX1558H are capable of dri-
ving inductive loads, but avoid exceeding the devices’
absolute maximum ratings. Usually the load inductance
is relatively small, and the MAX1558/MAX1558Hs’
input includes a substantial bulk capacitance from an
upstream regulator as well as local bypass capacitors,
limiting overshoot. If severe ringing occurs due to large
load inductance, clamp the MAX1558/MAX1558Hs’ out-
put below +6V and above -0.3V.
I
= 36400 / R
(Amps)
LIM(TYPICAL)
ISET
Do not use R
values below 26kΩ because the maxi-
ISET
mum current rating of the device may be exceeded.
R
values larger than 60kΩ are not recommended
ISET
and do not provide a lower limit current than 500mA.
If the output drops below 1V (typ), the MAX1558 shifts
to a short-circuit current-limit threshold that is 30%
above the programmed level given by the I
LIM(TYPICAL)
Turn-On and Turn-Off Behavior
In the absence of faults, the MAX1558/MAX1558Hs’
internal switches turn on and off slowly under the control
of the ON_ inputs. Transition times for both edges are
approximately 4ms. The slow charge-pump switch drive
minimizes load transients on the upstream power source.
Under thermal fault and UVLO, the power device turns
off rapidly (100ns) to protect the power device.
formula. If the short-circuit threshold is exceeded, the
switch shuts off immediately (no 20ms delay) and
ramps the current back up in approximately 3ms. If the
short persists and the current ramps all the way up to
the short-circuit limit again, the switch again turns off. If
the short still persists, the output pulses this way for
20ms, at which time the switch turns off and autoreset
mode begins.
Layout and Thermal Dissipation
To optimize the switch response time to output short-
circuit conditions, keep all traces as short as possible
to reduce the effect of undesirable parasitic induc-
tance. Place input and output capacitors no more than
5mm from device leads. All IN_ and OUT_ pins must be
connected with short traces to the power bus. Wide
power-bus planes provide superior heat dissipation
through the switch IN_ and OUT_ pins. While the
switches are on, power dissipation is small and the
package temperature change is minimal. Calculate the
power dissipation for this condition as follows:
Input Capacitor
INA and INB provide the power for all control and
charge-pump circuitry and must be connected together
externally. Connect a capacitor from IN_ to ground to
limit the input-voltage drop during momentary output
short-circuit conditions. A 0.1µF ceramic capacitor is
required for local decoupling; higher capacitor values
further reduce the voltage drop at the input. When dri-
ving inductive loads, a larger capacitance prevents
voltage spikes from exceeding the MAX1558/
MAX1558Hs’ absolute maximum ratings.
Output Capacitor
Place a 1µF or greater capacitor at each output for
noise immunity. When starting up into very large capac-
itive loads, the switch may pulse the output current at
the short-circuit current-limit program level until the out-
put voltage rises above 1V. Then, the capacitor contin-
ues to charge at the full, continuous current-limit
program level. There is no limit to the output capacitor
size, but to prevent a startup fault assertion, the capaci-
tor must charge up within the fault-blanking delay peri-
od. Typically, starting up into a 500µF or smaller
capacitor does not trigger a fault output. In addition to
bulk capacitance, small-value (0.1µF or greater) ceram-
ic capacitors improve the output’s resilience to electro-
static discharge (ESD).
P = (I
_)2 R
OUT
ON
For the maximum operating current (I
_ = 1.2A) and
OUT
the maximum on-resistance of the switch (125mΩ), the
power dissipation is:
P = (1.2A)2 x 0.125Ω = 180mW per switch
The worst-case power dissipation occurs when the
switch is in current limit and the output is greater than
1V. The instantaneous power dissipated in each switch
is the voltage drop across the switch multiplied by the
current limit. The fault-blanking circuit turns the output
off if the fault persists for 20ms, while the autoreset cir-
cuit can turn it back on after 20ms in the off state. Thus,
the average worst-case power is approximately 50% of
the instantaneous value.
P = 0.5 x (I ) x (V
- V
)
OUT_
LIM
IN_
10 ______________________________________________________________________________________
Dual, 3mm x 3mm, 1.2A/Programmable-Current
USB Switches with Autoreset
For a 5V input and 1V output, the maximum possible
Chip Information
power dissipation per switch is:
TRANSISTOR COUNT: 2932
P = 0.5 x (1.5A) x (5V - 1V) = 3W
PROCESS: BiCMOS
Since the package power dissipation is limited to
1952mW, the MAX1558/MAX1558H die temperature
exceeds the thermal-shutdown threshold and the
switch turns off. After the die temperature cools by
10°C, the switch turns on again. If the fault-overload
condition continues, the switch cycles on and off with a
duty cycle and period that is a function of the ambient
temperature and PC board layout.
A short across the output for more than 20ms places
the part in autoreset mode. With V
= 5V and an
IN_
autoreset test current of 30mA, the power dissipation
for a short-circuited output is given by:
P = (30mA) x 5V = 0.15W
______________________________________________________________________________________ 11
Dual, 3mm x 3mm, 1.2A/Programmable-Current
USB Switches with Autoreset
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
D
N
PIN 1
INDEX
AREA
E
E2
DETAIL A
C
L
C
L
A
L
L
e
e
PACKAGE OUTLINE, 6,8,10 & 14L,
TDFN, EXPOSED PAD, 3x3x0.80 mm
1
-DRAWING NOT TO SCALE-
21-0137
G
2
COMMON DIMENSIONS
SYMBOL
MIN.
0.70
2.90
2.90
0.00
0.20
MAX.
0.80
3.10
3.10
0.05
0.40
A
D
E
A1
L
k
0.25 MIN.
0.20 REF.
A2
PACKAGE VARIATIONS
DOWNBONDS
ALLOWED
N
6
D2
E2
e
JEDEC SPEC
b
PKG. CODE
T633-1
[(N/2)-1] x e
1.90 REF
1.90 REF
1.95 REF
1.50±0.10
1.50±0.10
1.50±0.10
1.50±0.10
1.50±0.10
1.50±0.10
1.70±0.10
1.70±0.10
2.30±0.10
2.30±0.10
2.30±0.10
2.30±0.10
2.30±0.10
2.30±0.10
2.30±0.10
2.30±0.10
0.95 BSC
0.95 BSC
0.65 BSC
0.65 BSC
0.65 BSC
0.50 BSC
0.40 BSC
0.40 BSC
MO229 / WEEA
MO229 / WEEA
MO229 / WEEC
MO229 / WEEC
MO229 / WEEC
MO229 / WEED-3
- - - -
0.40±0.05
0.40±0.05
0.30±0.05
0.30±0.05
0.30±0.05
0.25±0.05
0.20±0.05
0.20±0.05
NO
NO
T633-2
6
T833-1
8
NO
T833-2
8
1.95 REF
1.95 REF
2.00 REF
2.40 REF
2.40 REF
NO
T833-3
8
YES
NO
T1033-1
T1433-1
T1433-2
10
14
14
YES
NO
- - - -
PACKAGE OUTLINE, 6,8,10 & 14L,
TDFN, EXPOSED PAD, 3x3x0.80 mm
2
-DRAWING NOT TO SCALE-
21-0137
G
2
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
12 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2004 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.
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