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Advanced Monolithic Systems
FEATURES
* 3.3V and 5V Voltage Available* * Active High On/Off Control * Output Current of 150mA * Very Low Quiescent Current * Low Dropout Voltage of 80mV at 30mA * Very Low Noise * Short Circuit Protection * Internal Thermal Shutdown * Space Saving 5 Lead SOT-23 Package
AMS112
150mA LOW DROPOUT VOLTAGE REGULATOR WITH ON/OFF SWITCH
PRELIMINARY INFORMATION
APPLICATIONS
* Battery Powered Systems * Portable Consumer Equipment * Cordless Telephones * Portable (Notebook) Computers * Portable Instrumentation * Radio Control Systems * Personal Communication Equipment * Toys * Low Voltage Systems
GENERAL DESCRIPTION
The AMS112 series consists of positive fixed voltage regulators featuring an internal electronic switch controlled by TTL or CMOS logic levels. When the Control pin is pulled to a logic high level, the device is in the ON state. If the control function is not used, the control terminal should be connected to a logic high level or VIN, therefore allowing the regulator to be ON. The regulator will be ON when the control terminal voltage is grater than 1.8V. To lower the output noise level to 30Vrms, an external capacitor can be connected to the noise bypass pin. These devices feature very low quiescent current of 1mA when supplying 30mA loads (180A at no load). This unique characteristic and the low standby current (typ. 100nA) make the AMS112 ideal to use for standby power systems. Like other regulators the AMS112 series also includes internal current limiting and thermal shutdown. The AMS112 is offered in 3.3V and 5.0V output voltages, and is available in the 5-pin SOT-23 surface mount package.
ORDERING INFORMATION
PACKAGE TYPE OPERATING TEMP.
PIN CONNECTIONS
5 Lead SOT-23 (M1)
ON/OFF 1 GROUND 2 BYPASS 3 4 OUTPUT 5 INPUT
5L SOT-23 RANGE AMS112M1-X IND X =3.3V or 5V *For additional available fixed voltages contact factory
Bottom View
Advanced Monolithic Systems, Inc. 6680B Sierra Lane, Dublin, CA 94568 Phone (925) 556-9090 Fax (925) 556-9140
AMS112
ABSOLUTE MAXIMUM RATINGS (Note 1)
Input Voltage Power Dissipation Operating Temperature Range 16V 400mW -30C to +80C Maximum Junction Temperature +150C Storage Temperature -55C to +150C Lead Temperature (Soldering 10 sec) 230C
ELECTRICAL CHARACTERISTICS
Electrical Characteristics at TA=25C, VIN =VOUT +1V, CP = 0.1F unless otherwise noted. PARAMETER
Output Voltage Quiescent Current Standby Current Line Regulation Load Regulation Dropout Voltage
IN
CONDITIONS
(Note 2) V = VOUT+1V I = 0 mA, Except ICONT
O
Min.
-3
AMS112-X Typ.
170
Units Max.
+3 350 0.1 % A A mV mV mV mV mA dB Vrms mV/C V
V = 8V, at output off
IN IN
V = VOUT+1V to VOUT+6V 5mA I 60 mA
O
3 10 160 290 180 240 55 30 0.2 1.25
20 50 260 400
I = 60 mA
O
I = 150 mA
O
Output Current Ripple Rejection Output Noise Voltage Temperature Coefficient Noise Bypass Terminal Voltage Control Terminal Specifications On/Off Current On/Off Voltage Output On Output On Output Off Output Rise Time I = 30 mA, V
O CONT
100mVrms, IO=10mA 10Hz < f < 80kHz, IO=30mA IO=10mA, -20CTA+75C
12 1.8
30
A V V ms
0.6 = 0V to 1.8V 0.3
Note 1: Absolute Maximum Ratings are limits beyond which damage to the device may occur. For guaranteed performance limits and associated test conditions, see the Electrical Characteristics tables. Note 2: To ensure constant junction temperature, low duty cycle pulse testing is used.
Advanced Monolithic Systems, Inc. 6680B Sierra Lane, Dublin, CA 94568 Phone (925) 556-9090 Fax (925) 556-9140
AMS112
APPLICATION HINTS
Package Power Dissipation The package power dissipation is the level at which the thermal sensor monitoring the junction temperature is activated. The AMS112 shuts down when the junction temperature exceeds the limit of 150C. The junction temperature rises as the difference between the input power and output power increases. The mounting pad configuration on the PCB, the board material, as well as the ambient temperature affect the rate of temperature rise. The junction temperature will be low, even if the power dissipation is high, when the mounting of the device has good thermal conductivity. When mounted on the recommended mounting pad the power dissipation for the SOT-23 package is 400mW. For operation above 25C derate the power dissipation at 3.2 mW/C. To determine the power dissipation for shutdown when mounted, attach the device on the PCB and increase the input-to-output voltage until the thermal protection circuit is activated. Calculate the power dissipation of the device by subtracting the output voltage from the input voltage and multiply by the output current. The measurements should allow for the ambient temperature of the PCB. The value obtained from PD/ (150C - TA) is the derating factor. The PCB mounting pad should provide maximum thermal conductivity in order to maintain low device temperatures. As a general rule, the lower the temperature, the better the reliability of the device. The thermal resistance when the device is mounted is equal to: TJ = JA x PD + TA The internal limit for junction temperature is 150C. If the ambient temperature is 25C, then:
150C = JA x PD + 25C
Take a vertical line from the maximum operating temperature (75C) to the derating curve. 6. Read the value of PD at the point where the vertical line intersects the derating curve. This is the maximum power dissipation, DPD. The maximum operating current is: IOUT = (DPD/ (VIN(MAX) - VO) External Capacitors The AMS112 series require input and output decoupling capacitors. The required value of these capacitors depends on the application circuit and other factors. Because high frequency characteristics of electrolytic capacitors depend greatly on the type and even the manufacturer, the value of capacitance that works well with AMS112 for one brand or type may not necessary be sufficient with an electrolytic of different origin. Sometimes actual bench testing will be the only means to determine the proper capacitor type and value. To obtain stability in all general applications a high quality 4.7F aluminum electrolytic or a 2.2F tantalum electrolytic can be used. A critical characteristic of the electrolytic capacitors is their performance over temperature. The AMS112 is designed to operate to -30C, but some electrolytics will freeze around -30C therefore becoming ineffective. In such case the result is oscillation at the regulator output. For all application circuits where cold operation is necessary, the output capacitor must be rated to operate at the minimum temperature. In order to determine the minimum value of the output capacitor, for an application circuit, the entire circuit including the capacitor should be bench tested at minimum operating temperatures and maximum operating currents. After the minimum capacitance value has been found, the value should be doubled for actual use to cover for production variations both in the regulator and the capacitor. The recommended minimum capacitance for AMS112 is 2.2F. As a general rule, with higher output voltages the value of the output capacitance decreases, since the internal loop gain is reduced. Noise Bypass Capacitor The noise bypass capacitor should be connected as close as possible to pin 3 and ground. The recommended value for this capacitor is 0.01F. The noise bypass terminal is susceptible to external noise, and oscillation can occur when the bypass capacitor is not used and the solder pad for this pin is too large. Because of the high impedance of the noise bypass terminal, care should be taken if the bypass capacitor is not used.
5.
JA = 125C/ PD A simple way to determine PD is to calculate VIN x IIN when the output is shorted. As the temperature rises, the input gradually will decrease. The PD value obtained when the thermal equilibrium is reached, is the value that should be used. The range of usable currents can be found from the graph in figure 2.
(mW) PD 3
DPD
6 4 5
25
50
75 T (C)
150
Figure 2 Procedure: 1. Find PD. 2. PD1 is calculated as PD x (0.8 - 0.9). 3. Plot PD1 against 25C. 4. Connect PD1 to the point corresponding to the 150C.
Advanced Monolithic Systems, Inc. 6680B Sierra Lane, Dublin, CA 94568 Phone (925) 556-9090 Fax (925) 556-9140
AMS112
TYPICAL PERFORMANCE CHARACTERISTICS
INPUT OUTPUT DIFFERENTIAL (V)
INPUT OUTPUT DIFFERENTIAL (V)
0.6 0.5 0.4 0.3 0.2 0.1 0 0 80 40 120 JUNCTION TEMPERATURE ( C)
IO = 50mA IO = 10mA IO = 100mA
0.6 0.5 0.4 0.3 0.2 0.1 0 0 100 OUTPUT CURRENT (mA) 200
OUTPUT VOLTAGE DEVIATION (mV)
Dropout Voltage
Dropout Voltage
Line Transient Response 10 5 0 -5 -10
CL= 1000 pF
INPUT VOLTAGE =VO+1V to VO+2V
~ ~
2 1 0 0 15 30 TIME (s) 45
~ ~
OUTPUT VOLTAGE DEVIATION (mV)
Load Transient Response 300 75 0 -75
CL= 0.22F
Peak Output Current 30 QUIESCENT CURRENT (mA) 25 20 15 10 5 0 0 20 10 INPUT VOLTAGE (V) 30 0
Quiescent Current
VIN = 14V
OUTPUT CURRENT (mA)
250
TJ= 25C
200 150 100 50 0
TJ = 85C
LOAD CURRENT(mA)
TJ = -40C
~ ~
100
~ ~
50 0 15 30 TIME (s) 45
150 100 50 OUTPUT CURRENT (mA)
Quiescent Current 25 QUIESCENT CURRENT (mA) 20 15 10 3 2 1 0 -40
IO = 60mA IO = 30mA
Quiescent Current 0.7 QUIESCENT CURRENT (mA) 0.6 0.5 0.4 0.3 0.2 0.1 0
IO= 0mA
Ripple Rejection 85 80 RIPPLE REJECTION (dB) 75 70 65 60 55 50 45 1 10 100 1k 10k 100k FREQUENCY (Hz) 1M
~ ~
~ ~
0 40 80 120 TEMPERATURE ( C)
0 10 20 30 40 50 60 DROPOUT VOLTAGE (mV)
Advanced Monolithic Systems, Inc. 6680B Sierra Lane, Dublin, CA 94568 Phone (925) 556-9090 Fax (925) 556-9140

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