The AP2161 and AP2171 are integrated high-side power switches
optimized for Universal Serial Bus (USB) and other hot-swap
applications. The family of devices complies with USB 2.0 and
available with both polarities of Enable input. They offer current and
thermal limiting and short circuit protection as well as controlled rise
time and under-voltage lockout functionality. A 7ms deglitch capability
on the open-drain Flag output prevents false over-current reporting
and does not require any external components.
All devices are available in SO-8, MSOP-8EP, SOT25, and
U-DFN2018-6 packages
Pin Assignments
GND
IN
EN
( Top View )
1
2
3
IN
4
SO-8
8
NC
7
OUT
6
OUT
5
FLG
Features
Single USB Port Power Switches
Over-Current and Thermal Protection
1.5A Accurate Current Limiting
Reverse Current Blocking
95m On-Resistance
Input Voltage Range: 2.7V – 5.5V
0.6ms Typical Rise Time
Very Low Shutdown Current: 1µA (max)
Fault Report (FLG) with Blanking Time (7ms typ)
ESD Protection: 4kV HBM, 300V MM
Active Low (AP2161) or Active High (AP2171) Enable
Ambient Temperature Range: -40°C to +85°C
SOT25, SO-8, MSOP-8EP (Exposed Pad), and U-DFN2018-6:
Notes: 1. No purposely added lead. Fully EU Directive 2002/95/EC (RoHS) & 2011/65/EU (RoHS 2) compliant.
2. See http://www.diodes.com/quality/lead_free.html for more information about Diodes Incorporated’s definitions of Halogen- and Antimony-free, "Green"
and Lead-free.
3. Halogen- and Antimony-free "Green” products are defined as those which contain <900ppm bromine, <900ppm chlorine (<1500ppm total Br + Cl) and
<1000ppm antimony compounds.
for MSOP-8EP, SOT25 packages
Machine Model ESD Protection
for U-DFN2018-6, SO-8 packages
VIN
V
OUT
V
EN , VFLG
I
LOAD
T
J(MAX)
TST
Caution: Stresses greater than the 'Absolute Maximum Ratings' specified above, may cause permanent damage to the device. These are stress ratings only;
functional operation of the device at these or any other conditions exceeding those indicated in this specification is not implied. Device reliability may be
affected by exposure to absolute maximum rating conditions for extended periods of time.
Semiconductor devices are ESD sensitive and may be damaged by exposure to ESD events. Suitable ESD precautions should be taken when handling
and transporting these devices
Note: 4. UL Recognized Rating from -30°C to +70°C (Diodes qualified
Input Voltage 6.5 V
Output Voltage
Enable Voltage 6.5 V
Maximum Continuous Load Current Internal Limited A
Maximum Junction Temperature 150 °C
Storage Temperature Range (Note 4) -65 to +150 °C
T
from -65°C to +150°C)
ST
400 V
300 V
VIN +0.3
V
Recommended Operating Conditions(@T
= +25°C, unless otherwise specified.)
A
Symbol Parameter Min Max Units
V
IN
I
OUT
T
A
VIH High-Level Input Voltage on EN or EN
VIL Low-Level Input Voltage on EN or EN
Input voltage 2.7 5.5 V
Output Current 0 1.0 A
Operating Ambient Temperature -40 +85
Notes: 5. Test condition for SO-8: Device mounted on FR-4, 2oz copper, with minimum recommended pad layout.
6. Test condition for MSOP-8EP: Device mounted on 2” x 2” FR-4 substrate PC board, 2oz copper, with minimum recommended pad on top layer and
thermal vias to bottom layer ground plane.
7. Test condition for SOT25: Device mounted on FR-4, 2oz copper, with minimum recommended pad layout.
8. Test condition for U-DFN2018-6: Device mounted on FR-4 2-layer board, 2oz copper, with minimum recommended pad on top layer and 3 vias to bottom
A 0.01-F to 0.1-F X7R or X5R ceramic bypass capacitor between IN and GND, close to the device, is recommended. Placing a high-value
electrolytic capacitor on the input (10-F minimum) and output pin(s) is recommended when the output load is heavy. This precaution reduces
power-supply transients that may cause ringing on the input. Additionally, bypassing the output with a 0.01-F to 0.1-F ceramic capacitor improves
the immunity of the device to short-circuit transients.
Over-current and Short Circuit Protection
An internal sensing FET is employed to check for over-current conditions. Unlike current-sense resistors, sense FETs do not increase the series
resistance of the current path. When an over-current condition is detected, the device maintains a constant output current and reduc es the output
voltage accordingly. Complete shutdown occurs only if the fault stays long enough to activate thermal limiting.
Three possible overload conditions can occur. In the first condition, the output has been shorted to GND before the device is enabled or before VIN
has been applied. The AP2161/AP2171 senses the short circuit and immediately clamps output current to a certain safe level namely I
LIMIT
.
In the second condition, an output short or an overload occurs while the device is enabled. At the instance the overload occurs, highe r curr ent m ay
flow for a very short period of time before the current limit function can react. After the current limit function has tripped (reached the over-current
trip threshold), the device switches into current limiting mode and the current is clamped at I
LIMIT
.
In the third condition, the load has been gradually increased beyond the recommended operating current. The current is permitted to rise until the
current-limit threshold (I
) is reached or until the thermal limit of the device is exceeded. The AP2161/AP2171 is capable of delivering current up
TRIG
to the current-limit threshold without damaging the device. Once the threshold has been reached, the device switches into its current limiting mode
and is set at I
LIMIT
.
Note that when the output has been shorted to GND at extremely low temperature (< -30°C), a minimum 120-F electrolytic capacitor on the output
pin is recommended. A correct capacitor type with capacitor voltage rating and temperature characteristics must be properly chosen so that
capacitance value does not drop too low at the extremely low temperature operation. A recommended capacitor should have temperature
characteristics of less than 10% variation of capacitance change when operated at extremely low temp. Our recommended aluminum electrolytic
capacitor type is Panasonic FC series.
FLG Response
When an over-current or over-temperature shutdown condition is encountered, the FLG open-drain output goes a ctive low after a nominal 7-ms
deglitch timeout. The FLG output remains low until both over-current and over-temperature conditions are removed. Connecting a heavy capacitive
load to the output of the device can cause a momentary over-current condition, which does not trigger the FLG due to the 7-ms deglitch timeout.
The AP2161/AP2171 is designed to eliminate false over-current reporting without the need of external components to remove unwanted pulses.
Power Dissipation and Junction Temperature
The low on-resistance of the internal MOSFET allows the small surface-mount packages to pass large current. Using the maximum operating
ambient temperature (T
= R
P
D
DS(ON)
× I2
) and R
A
, the power dissipation can be calculated by:
DS(ON)
Finally, calculate the junction temperature:
T
= PD x R
J
JA
+ TA
Where:
T
= Ambient temperature °C
A
R
= Thermal resistance
JA
= Total power dissipation
P
D
Thermal Protection
Thermal protection prevents the IC from damage when heavy-overload or short-circuit faults are present for extended periods of time. The
AP2161/AP2171 implements a thermal sensing to monitor the operating junction temperature of the power distribution switch. Once the die
temperature rises to approximately 145°C due to excessive power dissipation in an over-current or short-circuit condition, the internal thermal
sense circuitry turns the power switch off, thus preventing the power switch from damage. H ysteresis is built into the thermal sense circuit allowing
the device to cool down approximately 25°C before the switch turns back on. The switch continues to cycle in this manner until the load fault or
input power is removed. The FLG open-drain output is asserted when an over-temperature shutdown or over-current occurs with 7-ms deglitch.
Under-voltage lockout function (UVLO) keeps the internal power switch from being turned on until the power supply has reached at least 1.9V, even
if the switch is enabled. Whenever the input voltage falls below approximately 1.9V, the power switch is quickly turned off. This facilitates the design
of hot-insertion systems where it is not possible to turn off the power switch before input power is removed.
Host/Self-Powered And Bus-Powered HUBs
Hosts and self-powered hubs have a local power supply that powers the embedded functions and the downstream ports (see Figure 2). This power
supply must provide from 5.25V to 4.75V to the board side of the downstream connection under full-load and no-load conditions. Hosts and SPHs
are required to have current-limit protection and must report over-current conditions to the USB controller. Typical SPHs are desktop PCs, monitors,
printers, and stand-alone hubs.
Figure 2 Typical One-Port USB Host / Self-Powered Hub
Generic Hot-Plug Applications
In many applications it may be necessary to remove modules or pc boards while the main unit is still operating. These are considered hot-plug
applications. Such implementations require the control of current surges seen by the main power supply and the card being inserted. The most
effective way to control these surges is to limit and slowly ramp the current and voltage being applied to the card, similar to the way in which a
power supply normally turns on. Due to the controlled rise times and fall times of the AP2161/AP2171, these devices can be used to provide a
softer start-up to devices being hot-plugged into a powered system. The UVLO feature of the AP2161/AP2171 als o ensures that the switch is off
after the card has been removed, and that the switch is off during the next insertion.
By placing the AP2161/AP2171 between the VCC input and the rest of the circuitry, the input power reaches these devices first after insertion. The
typical rise time of the switch is approximately 1ms, providing a slow voltage ramp at the output of the device. This implementation controls system
surge current and provides a hot-plugging mechanism for any device.
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