AAT3216 Datasheet, PDF (10/16 Pages) List of Unclassifed Manufacturers – 150mA MicroPower™ LDO with PowerOK

AAT3216
150mA MicroPower™ LDO with PowerOK
Applications Information
Consult capacitor vendor data sheets carefully
when selecting capacitors for LDO regulators.
POK Output
The AAT 3216 features an integrated Power-OK
comparator which can be used as an error flag.
The POK open-drain output goes low when OUT is
6% below its nominal regulation voltage. Connect
a pull-up resistor from POK to OUT or IN. A
delayed POK signal can be implemented with a
capacitor in parallel with the pull-up resistor.
Enable Function
The AAT3216 features an LDO regulator enable/
disable function. This pin (EN) is active high and is
compatible with CMOS logic. To assure the LDO
regulator will switch on, the EN turn on control level
must be greater than 2.0 volts. The LDO regulator
will go into the disable shutdown mode when the
voltage on the EN pin falls below 0.6 volts. If the
enable function is not needed in a specific applica-
tion, it may be tied to V_IN to keep the LDO regula-
tor in a continuously on state.
When the LDO regulator is in the shutdown mode,
an internal 1.5kΩ resistor is connected between
V_OUT and GND. This is intended to discharge C_OUT
when the LDO regulator is disabled. The internal
1.5kΩ has no adverse effect on device turn on time.
Short Circuit Protection
The AAT3216 contains an internal short circuit pro-
tection circuit that will trigger when the output load
current exceeds the internal threshold limit. Under
short circuit conditions the output of the LDO regu-
lator will be current limited until the short circuit
condition is removed from the output or LDO regu-
lator package power dissipation exceeds the
device thermal limit.
Thermal Protection
The AAT3216 has an internal thermal protection cir-
cuit which will turn on when the device die temper-
ature exceeds 150°C. The internal thermal protec-
tion circuit will actively turn off the LDO regulator
output pass device to prevent the possibility of over
temperature damage. The LDO regulator output
will remain in a shutdown state until the internal die
temperature falls back below the 150°C trip point.
The combination and interaction between the short
circuit and thermal protection systems allow the
LDO regulator to withstand indefinite short circuit
conditions without sustaining permanent damage.
No-Load Stability
The AAT3216 is designed to maintain output volt-
age regulation and stability under operational no-
load conditions. This is an important characteristic
for applications where the output current may drop
to zero.
Reverse Output to Input Voltage
Conditions and Protection
Under normal operating conditions a parasitic
diode exists between the output and input of the
LDO regulator. The input voltage should always
remain greater then the output load voltage main-
taining a reverse bias on the internal parasitic
diode. Conditions where V_OUT might exceed V_IN
should be avoided since this would forward bias
the internal parasitic diode and allow excessive
current flow into the V_OUT pin possibly damaging
the LDO regulator.
In applications where there is a possibility of V_OUT
exceeding V_IN for brief amounts of time during nor-
mal operation, the use of a larger value C_IN capaci-
tor is highly recommended. A larger value of C_IN
with respect to C_OUT will effect a slower C_IN decay
rate during shutdown, thus preventing V_OUT from
exceeding V_IN. In applications where there is a
greater danger of V_OUT exceeding V_IN for extended
periods of time, it is recommended to place a schot-
tky diode across V_IN to V_OUT (connecting the cath-
ode to V_IN and anode to V_OUT). The Schottky diode
forward voltage should be less than 0.45 volts.
Thermal Considerations and High
Output Current Applications
The AAT3216 is designed to deliver a continuous
output load current of 150mA under normal operat-
ing conditions.
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