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G528A Schematic ( PDF Datasheet ) - Global Mixed-mode Technology

Teilenummer G528A
Beschreibung USB High-Side Power Switch Advance Information
Hersteller Global Mixed-mode Technology
Logo Global Mixed-mode Technology Logo 




Gesamt 8 Seiten
G528A Datasheet, Funktion
Global Mixed-mode Technology Inc.
G528/G528A
USB High-Side Power Switch Advance Information
Features
„ Typical 110mΩ, Low MOSFET on resistance, at
5.0V
„ 3.0V to 5.5V operating range
„ 100 µA typical on-state supply current
„ 1µA typical standby supply current
„ Output can be forced higher than input when
operating in off state.
„ 1.4A Typical current limit
„ Thermal shutdown protection
„ 2.4V typical under-voltage lockout (UVLO)
„ Open-drain fault flag pin
„ Slow turn-on (soft-start) and fast turnoff
„ Logic level enable pin, available with active-low
version (G528), or available with active-high
version (G528A)
„ UL Approved_#E232223
Applications
„ High-side power protection switch
„ USB power management
„ USB host and self-powered hubs
„ USB Bus-powered hubs
„ Hot plug-in power supplies
„ Battery-charger circuits
General Description
The G528/G528A is an integrated high-side power
switch optimized for self-powered and bus-powered
Universal Serial Bus (USB) applications.
The G528/G528A satisfies the USB standards. The
switch's low on-resistance meets USB voltage drop
requirements. When the output load exceeds cur-
rent-limit threshold, G528/G528A switches into con-
stant-current mode and limit the output current to a
safe level, which is typically 1.4A. An open-drain flag
output is also available to indicate fault conditions to
the local USB controller. Soft start eliminates the mo-
mentary voltage drop on the upstream port that may
occur when the switch is enabled in bus-powered
applications.
Besides, a thermal shutdown circuit is included to
prevent catastrophic switch failure caused by increas-
ing power dissipation when continuous heavy loads or
short circuit occurs. A under-voltage lockout (UVLO)
circuit ensures that the device remains off unless there
is a valid input voltage present, and an enable input
that is compatible with both 3.3V and 5V logic.
Ordering Information
ORDER
NUMBER
G528P1U
G528AP1U
Note: P1: SOP-8L
U: Tape & Reel
ORDER NUMBER
(Pb free)
G528P1Uf
G528AP1Uf
Pin Configuration
ENABLE
Active Low
Active High
TEMP.
RANGE
-40°C to +85°C
-40°C to +85°C
PACKAGE
SOP-8
SOP-8
Ver: 1.2
May 17, 2005
G528/G528A
GND 1
8 OUT
IN 2
7 OUT
IN 3
6 OUT
EN 4
(EN)
SOP-8
5 FLG
1
TEL: 886-3-5788833
http://www.gmt.com.tw






G528A Datasheet, Funktion
Global Mixed-mode Technology Inc.
G528/G528A
Functional Description
The G528/G528A is high-side 1-channel switch with
active-low enable input. Fault conditions turn off or
inhibit turn-on of the output transistors.
Input and Output
IN (input) is the power supply connection to the logic
circuitry and the source of the output MOSFET. OUT
(output) is the drain of the output MOSFET. In a typical
application, current flows through the switch from IN to
OUT toward the load. All OUT pins must be connected
together to the load.
The output MOSFET and driving circuit are also de-
signed to allow the MOSFET drain to be externally
forced to a higher voltage than the source (VOUT > VIN)
when the switch is off. In this situation, the
G528/G528A avoids undesirable drain-to-body diode
current flow by connecting the body to the most posi-
tive voltage. If VOUT >VIN when switch is enabled, cur-
rent will flow from VOUT to VIN.
Switch Enabled into Heavy Load
If the switch is powered on or enabled into a heavy
load or short-circuit, the switch immediately goes into
a constant-current mode, reducing the output voltage.
See the "Enable into Short Circuit" graph.
Heavy Load Applied to Enabled Switch
When a heavy load is applied, a large current may
flow from the switch. The current limit circuit may shut
the switch off briefly, then fold back into con-
stant-current mode. See the “Short Applied to Output”
graph and the "Ramped Load to Enable Device"
graph.
Fault Flag
FLG is a 2-channel, open-drain MOSFET output.
Thefault-flag is active (low) for one or more of the fol-
lowing conditions: current limiting, undervoltage, or
thermal shutdown. The flag output MOSFET is capa-
ble of sinking a 10mA load to typically 100mV above
ground.
Thermal Shutdown
Thermal shutdown protects G528/G528A from exces-
sive power dissipation. If the die temperature exceeds
135°C, the MOSFETS switch is shut off. 10°C of hys-
tersis prevents the switch from turning on until the die
temperature drops to 125°C. Thermal shutdown circuit
functions only when the switch is enabled.
Undervoltage Lockout
UVLO (undervoltage lockout) prevents the output
MOSFET from turning on until IN (input voltage) ex-
ceeds 2.5V typically. After the switch turns on, if the
voltage drops below 2.3V typically, UVLO shuts off the
output MOSFET. UVLO detection functions only when
the switch is enabled.
Current Sensing and Limiting
The current limit threshold is preset internally. The
preset level prevents damage to the output MOSFET
and external load but allows a minimum current of
0.5A through the output MOSFET.
A current sense circuit senses the output current of
MOSFET switch. If output current exceeds the current
limit threshold, the output MOSFET switch is shut off.
The reaction to an overcurrent is measured with the
following scenarios:
Applications Information
Supply filtering
A 0.1µF to 1µF bypass capacitor from IN to GND as
shown in Figure 1, located near the G528/G528A, 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 maxi-
mum supply voltage (VIN max = 6V) even for a short du-
ration.
3.0V to 5.5V
G528
0.1 µF to 1 µF
IN OUT
off
on
EN
GND
Figure 1. Supply Bypassing
Ver: 1.2
May 17, 2005
TEL: 886-3-5788833
http://www.gmt.com.tw
6

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