2525
AND
2535
A2525EM
GATE
CONTROL
USB POWER CONTROL SWITCHES
The A2525EL/M and A2535EL/M are integrated high-side power
switches, optimized for self-powered and bus-powered Universal Serial
Bus (USB) applications. Few external components are necessary to
satisfy USB requirements. The A2525EL/EM ENABLE inputs are
active high; the A2535EL/EM are active low.
All devices are ideally suited for USB applications. Each switch
channel supplies up to 500 mA as required by USB peripheral devices.
In addition, the switch’s low on-resistance permits achieving the USB
voltage-drop requirements. Fault current is limited to typically
750 mA, satisfying the UL 25 VA safety requirements, and a flag
output is available to indicate a fault condition to the local USB
controller. Momentary voltage drops that may occur on the upstream
port when the switch is enabled in bus-powered applications is elimi-
nated by a “soft start” feature.
Additional features include thermal shutdown to prevent catastrophic
switch failure from high-current loads, undervoltage lockout to ensure
that the device remains OFF unless there is a valid input voltage
present, and 3.3 V and 5 V logic-compatible enable inputs.
These switches are provided in 8-pin mini-DIP (suffix ‘M’) and
8-lead SOIC (suffix ‘L’) packages.
Data Sheet
27447.1*
EN
FLG
GND
NC
1
2
3
4
8
7
OUT
IN
NC
NC
NC
NC
NC
6
5
Dwg. PP-070A
Note that the A2525EM (DIP) and the
A2525EL (SOIC) are electrically identical and
share a common terminal number assignment.
ABSOLUTE MAXIMUM RATINGS
Supply Voltage, V
IN
.....................
6.0 V
Output Voltage, V
OUT
..................
6.0 V
Output Current,
I
OUT
.................
Internally Limited
ENABLE Voltage Range,
V
EN
.........................
–0.3 V to 10 V
Fault Flag Voltage, V
FLG
..............
8.0 V
Fault Flag Current, I
FLG
.............
50 mA
Package Power Dissipation,
P
D
.................................
See Graph
Operating Temperature Range,
T
A
..........................
-40
°
C to +85
°
C
Junction Temperature, T
J
.......
+150
°
C*
Storage Temperature Range,
T
S
...........................
-65
°
C to 150
°
C
* Fault conditions that produce excessive
junction temperature will activate device
thermal shutdown circuitry. These conditions
can be tolerated but should be avoided.
T
C
A
T
N
O
C
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
Y
R
O
T
C
A
F
Features
2.7 V to 5.8 V Input
Up to 500 mA Continuous Load Current per Port
140 mΩ Maximum ON-Resistance
1.25 A Maximum Short-Circuit Current Limit
Individual Open-Drain Fault Flag Outputs
100
µA
Typical ON-State Supply Current
<1
µA
Typical OFF-State Supply Current
Outputs Can be Forced Higher Than Input (off-state)
Thermal Shutdown
2.2 V Typical Undervoltage Lockout
0.6 ms Turn On (soft-start) and Fast Turn Off
A2525 (active-high) Improved Replacement for MIC2525-1
A2535 (active-low) Improved Replacement for MIC2525-2
USB Hosts and Self-Powered Hubs
USB Bus-Powered Hubs
Hot Plug-In Power Supplies
Battery-Charger Circuits
Applications
2525
AND
2535
USB
POWER CONTROL
SWITCHES
FUNCTIONAL BLOCK DIAGRAM
FLG
A2535 ONLY
GATE
CONTROL
EN
CHARGE
PUMP
OUT
CURRENT
LIMIT
OSC
1.2 V
REF.
TSD
UVLO
IN
GND
Dwg. FP-049
A2535EM
GATE
CONTROL
ALLOWABLE PACKAGE POWER DISSIPATION IN WATTS
2.5
2.0
EN
FLG
GND
NC
1
2
3
4
8
7
OUT
IN
NC
NC
1.5
NC
NC
NC
6
5
SUFFIX 'M', R
θJA
= 60°C/W
1.0
0.5
SUFFIX 'L', R
θJA
= 108°C/W
Dwg. PP-070-1A
Note that the A2535EM (DIP) and the
A2535EL (SOIC) are electrically identical and
share a common terminal number assignment.
0
25
50
75
100
125
AMBIENT TEMPERATURE IN
°C
150
Dwg. GP-009-2
2
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
Copyright © 2000, Allegro MicroSystems, Inc.
2525
AND
2535
USB
POWER CONTROL
SWITCHES
Electrical Characteristics
at T
A
= 25
°
C, V
IN
= 5 V.
Limits
Parameter
Operating Voltage Range
Switch Resistance
Test Conditions
V
IN
V
IN
= 5 V, I
OUT
= 500 mA
V
IN
= 3.3 V, I
OUT
= 500 mA
Output Leakage Current
Maximum Load Current
Short-Circuit Current Limit
Current-Limit Threshold
ENABLE Input Threshold
Output enabled into load, V
OUT
= 4 V
Ramped load applied to enabled output, V
OUT
≤
4 V
Low-to-high transition
High-to-low transition
ENABLE Input Hysteresis
ENABLE Input Current
ENABLE Input Cap.
Output Turn-On Delay
Output Turn-On Rise Time
Output Turn-Off Delay
Output Turn-Off Fall Time
Error Flag Output
Resistance
Error Flag Off Current
Supply Current
R
L
= 10
Ω,
C
L
= 1
µF,
50% V
ENABLE
to 10% V
OUT
R
L
= 10
Ω,
C
L
= 1
µF,
10% V
OUT
to 90% V
OUT
R
L
= 10
Ω,
C
L
= 1
µF,
50% V
ENABLE
to 90% V
OUT
R
L
= 10
Ω,
C
L
= 1
µF,
90% V
OUT
to 10% V
OUT
V
IN
= 5 V, I
L
= 10 mA
V
IN
= 3.3 V, I
L
= 10 mA
V
FLG
= 5 V
Switch disabled (see note), OUT = open
Switch enabled (see note), OUT = open
UVLO Threshold
Increasing V
IN
Decreasing V
IN
Over-Temperature
Shutdown Threshold
Increasing T
J
Decreasing T
J
V
EN
= 0 V to 5.5 V
Output disabled, V
IN
= 5 V, V
OUT
= 0
Min
2.7
–
–
–
500
0.5
–
–
0.8
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
Typ
–
100
100
<1.0
–
0.75
0.9
2.1
1.9
0.2
±0.01
1.0
0.5
0.6
10
25
8.0
10
0.01
0.2
100
2.35
2.2
165
155
Max
5.8
140
140
10
–
1.25
–
2.4
–
–
±1.0
–
–
–
–
–
–
–
–
5.0
160
–
–
–
–
Units
V
mΩ
mΩ
µA
mA
A
A
V
V
V
µA
pF
ms
ms
µs
µs
Ω
Ω
µA
µA
µA
V
V
°C
°C
Note — Disabled is
≤
0.8 V and enabled is
≥
2.4 V (active high) for the A2525EL/EM. Disabled is
≥
0.8V
IN
and enabled is
≤
0.8 V
(active low) for the A2535EL/EM.
www.allegromicro.com
3
2525
AND
2535
USB
POWER CONTROL
SWITCHES
FUNCTIONAL DESCRIPTION
Power switch
The power switch is an N-channel MOSFET with a maximum
on-state resistance of 140 mΩ (V
IN
= 5 V). Configured as a
high-side switch, the power switch prevents current flow in
either direction if disabled. The drain body diode is discon-
nected from the source when the switch is OFF allowing the
output voltage to exceed the input voltage without causing
current conduction. The power switch supplies a minimum of
500 mA per switch.
Charge pump
An internal charge pump supplies power to the driver circuit
and provides the necessary voltage to pull the gate of the
MOSFET above the source. The charge pump operates from
input voltages as low as 2.7 V. The charge pump is limited to
2.5
µA
to establish a controlled turn on time of typically 1 ms.
Driver
The driver controls the gate voltage of the power switch. To
limit large current surges and reduce the associated electromag-
netic interference (EMI) produced, the driver incorporates
circuitry that controls the rise times and fall times of the output
voltage. The rise time is typically 1 ms.
ENABLE (EN or EN)
The logic enable disables the power switch and the bias for the
charge pump, driver, and other circuitry to reduce the supply
current to less than 5
µA
maximum when a logic high is present
on EN (A2525) or a logic low is present (A2535). The proper
logic level restores bias to the drive and control circuits and
turns the power ON. The enable input is a compatible with both
TTL and CMOS logic levels.
Fault Flag (FLG)
This open drain output is asserted (active low) when an
overcurrent or over temperature condition is encountered. The
output will remain asserted until the overcurrent or over
temperature condition is removed.
Current sense
A sense FET monitors the current supplied to the load. The
sense FET measures current more efficiently than conventional
resistance methods. When an overload or short circuit is
encountered, the current-sense circuitry sends a control signal to
the driver. The driver in turn reduces the gate voltage and
drives the power FET into its saturation region, which switches
the output into a constant-current mode and holds the current
constant while varying the voltage on the load.
Thermal sense
An internal thermal-sense circuit shuts off the power switch
when the junction temperature rises to approximately 165°C.
Hysteresis is built into the thermal sense circuit. After the
device has cooled approximately 10°C, the switch turns back
ON. The switch continues to cycle off and on until the fault is
removed.
Undervoltage lockout
A voltage-sense circuit monitors the input voltage. When the
input voltage is approximately 2 V, a control signal turns OFF
the power switch.
4
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
2525
AND
2535
USB
POWER CONTROL
SWITCHES
NO-LOAD SWITCHING PERFORMANCE
V
OUT
1 V/
200
µs/
V
OUT
1 V/
50
µs/
V
ENABLE
V
ENABLE
V
OUT
1 V/
50
µs/
V
ENABLE
www.allegromicro.com
5
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