The AP7335 is a 300mA, adjustable and fixed output
voltage, low dropout linear regulator. The device included
pass element, error amplifier, band-gap, current limit and
thermal shutdown circuitry. The device is turned on when
EN pin is set to logic high level.
The characteristics of low dropout voltage and low quiescent
current make it suitable for low power applications, for
example, battery powered devices. The typical quiescent
current is approximately 35μA. Built-in current-limit and
thermal-shutdown functions prevent IC from damage in fault
conditions.
This device is available with adjustable output from 0.8V to
5.0V, and fixed version with 0.8V, 1.0V, 1.2V, 1.5V, 1.8V,
2.0V, 2.5V, 2.7V, 2.8V, 3.0V, 3.3V and 3.9V outputs. Please
contact your local sales office for any other voltage options.
NEW PRODUCT
The AP7335 is available in SOT25 and DFN2020-6
packages.
Symbol Parameter Test Conditions Min Typ. Max Unit
V
REF
I
ADJ
V
OUT
ΔV
OUT
ΔV
/V
IN
ΔV
OUT
V
OUT
V
Dropout
I
Q
I
SHDN
I
NEW PRODUCT
LEAK
tST
PSRR PSRR (Note 4)
I
SHORT
I
LIMIT
V
IL
V
IH
I
EN
T
SHDN
T
HYS
θ
JA
Notes: 3. Dropout voltage is the voltage difference between the input and the output at which the output voltage drops 2% below its nominal value. This
parameter only applies to input voltages above minimum V
4. At V
5. Test condition for all packages: Device mounted on FR-4 substrate PC board, 1oz copper, with minimum recommended pad layout.
AP7335
Document number: DS32259 Rev. 3 - 2
= V
OUT
+1V, C
IN
ADJ Reference Voltage (Adjustable version)
= 1μF, C
IN
OUT
= 1μF, V
= 2V, unless otherwise stated)
EN
I
= 0mA
OUT
0.8 V
ADJ Leakage (Adjustable version) 0.1 1 μA
T
= -40oC to 85oC,
Output Voltage Accuracy
/
Line Regulation
/
Load Regulation
Dropout Voltage (Note 3)
Input Quiescent Current
Input Shutdown Current
Input Leakage Current
Start-up Time
Short-circuit Current
Current limit
EN Input Logic Low Voltage
EN Input Logic High Voltage
EN Input Current
A
I
= 10% of I
OUT
V
= (V
IN
= VIN, I
V
EN
V
= (V
IN
I
= 1mA to 300mA
OUT
< 2.5V, I
V
OUT
V
≥ 2.5V, I
OUT
= VIN, I
V
EN
= 0V, I
V
EN
= 0V, OUT grounded
V
EN
V
= 0V to 2.0V in 1μs,
EN
= 300mA
I
OUT
V
= [V
IN
f = 1kHz, I
V
= V
IN
IN-Min
< 0.2V (fixed) or
V
OUT
25% of V
V
= V
IN
IN-Min
V
OUT/ROUT
= V
V
IN
IN-Min
= V
V
IN
IN-Min
= 0V or V
V
IN
OUT-Max
+1V) to V
OUT
= 1mA
OUT
+1V) to V
OUT
OUT
OUT
= 0mA
OUT
= 0mA
OUT
+1V]VDC + 0.5V
OUT
= 50mA
OUT
to V
(ADJ version)
OUT
to V
= 1.2A
to V
to V
IN-Max
IN-Max
IN-Max
= 300mA
= 300mA
,
IN-Max
,
IN-Max
IN-Max
IN-Max
,
,
ppAC
-2 2 %
0.02 0.20 %/V
-0.6 0.6 %
170 300
150 200
35 80 μA
0.1 1
0.1 1
220 μs
,
65 dB
140 mA
400 600 mA
0.4 V
1.4 V
-1 1 μA
Thermal shutdown threshold 145 °C
Thermal shutdown hysteresis 15 °C
A 1μF ceramic capacitor is recommended between IN and
GND pins to decouple input power supply glitch and
noise. The amount of the capacitance may be increased
without limit. This input capacitor must be located as close
as possible to the device to assure input stability and
reduce noise. For PCB layout, a wide copper trace is
required for both IN and GND pins. A lower ESR capacitor
type allows the use of less capacitance, while higher ESR
type requires more capacitance.
Output Capacitor
The output capacitor is required to stabilize and improve
the transient response of the LDO. The AP7335 is stabl e
with very small ceramic output capacitors. Using a
ceramic capacitor value that is at least 1μF with ESR >
15mΩ on the output ensures stability. High er capacitance
values help to improve line and load transient response .
The output capacitance may be increased to keep low
undershoot and overshoot. Output capacitor must be
placed as close as possible to OUT and GND pins.
NEW PRODUCT
100
Unstable Range
10
Ω
1
Stable
OUT
0.1
C ESR ()
0.01
0.001
Unstabl e Range
050100150200250300
Region of Stable C ESR vs. Load Current
LOAD CURRENT (mA)
OUT
Adjustable Operation
The AP7335 provides output voltage from 0.8V to 5.0V
through external resistor divider as shown below.
Rearranging the equation will give the following that is
used for adjusting the output to a particular voltage:
⎛
V
OUT
⎜
R
R
2
1
⎜
V
REF
⎝
To maintain the stability of the internal refer ence voltag e,
need to be kept smaller than 80kΩ.
R
2
No Load Stability
Other than external resistor divider, no minimum load is
required to keep the device stable. The device will
remain stable and regulated in no load condition.
ON/OFF Input Operation
The AP7335 is turned on by setting the EN pin high, and
is turned off by pulling it low. If this feature is not used,
the EN pin should be tied to IN pin to keep the regulator
output on at all time. To ensure proper operation, the
signal source used to drive the EN pin must be a ble to
swing above and below the specified turn- on/off voltage
thresholds listed in the Electrical Characteris tics section
under V
and VIH.
IL
Current Limit Protection
When output current at OUT pin is higher than current
limit threshold, the current limit protection will be
triggered and clamp the output current t o approximately
600mA to prevent over-current and to protect the
regulator from damage due to overheating.
Short Circuit Protection
When OUT pin is short-circuit to GND, short circuit
protection will be triggered and cl amp the output current
to approximately 140mA. This feature protects the
regulator from over-current and damage due to
overheating.
Thermal Shutdown Protection
Thermal protection disables the output when the junction
temperature rises to approximately +145°C, allowing the
device to cool down. When the junction temperature
reduces to approximately +130°C the output circuitry is
enabled again. Depending on power dissipation,
thermal resistance, and ambient temperature, the
thermal protection circuit may cycle on and off.
This cycling limits the heat dissipation of the regulator,
protecting it from damage due to overheating.
Page 11
Application Notes
Ultra Fast Start-up
After enabled, the AP7335 is able to provide full power in
as little as tens of microseconds, typically 220µs, without
sacrificing low ground current. This feature will help load
circuitry move in and out of standby mode i n real time,
eventually extend battery life for mobile phones and
other portable devices.
Fast Transient Response
Fast transient response LDO can extend battery life.
TDMA-based cell phone protocols such as Global
System for Mobile Communications (GSM) have a
transmit/receive duty factor of only 12.5 percent,
enabling power savings by putting much of the
baseband circuitry into standby mode in between
transmit cycles. In baseband circuits, the load often
transitions virtually instantaneously from 100µA to
100mA. To meet this load requirement, the LDO must
react very quickly without a large voltage drop or
NEW PRODUCT
overshoot — a requirement that cannot be met with
conventional, general-purpose LDO.
The AP7335’s fast transient response from 0 to 300mA
provides stable voltage supply for fast DSP and GSM
chipset with fast changing load.
AP7335
300mA, LOW QUIESCENT CURRENT, FAST TRANSIENT
LOW DROPOUT LINEAR REGULATOR
Low Quiescent Current
The AP7335, consuming only around 35µA for all input
range, provides great power saving in portable and low
power applications.
Wide Output Range
The AP7335, with a wide output range of 0.8V to 5.0V,
provides a versatile LDO solution for many portable
applications.
Power Dissipation
The device power dissipation and proper sizing of the
thermal plane that is connected to the thermal pad is
critical to avoid thermal shutdown and ensure reliable
operation. Power dissipation of the device depends on
input voltage and load conditions and c an be calculated
by:
= (V
- V
P
D
The maximum power dissipation, handled by the device,
depends on the maximum junction to ambient thermal
resistance, maximum ambient temperature, and
maximum device junction temperature, which can be
calculated by the equation in the following:
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