MAX1793EUE-20+ [MAXIM]
FIXED/ADJUSTABLE POSITIVE LDO REGULATOR;
| 型号： | MAX1793EUE-20+ |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | FIXED/ADJUSTABLE POSITIVE LDO REGULATOR |
| 文件： | 总11页 (文件大小：406K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-1654; Rev 3; 1/12
Low-Dropout, Low I , 1A Linear Regulator
Q
MAX1793
General Description
Features
The MAX1793 low-dropout linear regulator (LDO) oper-
ates from +2.5V to +5.5V and delivers a guaranteed 1A
load current with a low 210mV dropout. The high-accu-
racy ( 1ꢀ) output voltage is preset at an internally
trimmed voltage (see the Ordering Information) or can
be adjusted from 1.25V to 5.0V with an external resis-
tor-divider.
o Guaranteed 1A Output Current
o Low 210mV Dropout at 1A
o Up to 1% Output Voltage Accuracy
Preset at 1.5V, 1.8V, 2.0V, 2.5V, 3.3V or 5.0V
Adjustable from 1.25V to 5.0V
o Reset Output (4ms Delay)
o Low 125µA Ground Current
o 0.1µA Shutdown
An internal pMOS pass transistor allows a low 125µA
supply current, making the MAX1793 ideal for battery-
operated portable equipment. Other features include a
built-in reset output, low-power shutdown, and short-cir-
cuit and thermal-overload protection. The MAX1793 is
available in a 1.5W, 16-pin power TSSOP package,
which is 30ꢀ smaller than a SOT223 package and only
1.1mm high.
o Low 115µV
Output Noise
RMS
o Thermal-Overload Protection
o Output Current Limit
o Tiny TSSOP Power Package (1.5W)
30% Smaller than SOT223 (only 1.1mm high)
Ordering Information
†
TEMP
RANGE
PIN-
PACKAGE
V
OUT
(V)
PART
________________________Applications
MAX1793EUE-50 -40°C to +85°C 16 TSSOP-EP* 5.0 or Adj
MAX1793EUE-33 -40°C to +85°C 16 TSSOP-EP* 3.3 or Adj
Notebook Computers
Cordless Telephones
Cellular Phones
MAX1793EUE-33/V -40°C to +85°C 16 TSSOP-EP* 3.3 or Adj
Ordering Information continued at end of data sheet
*EP = Exposed pad.
Modems
†
Handheld Instruments
PDAs and Palmtop Computers
Contact factory for other preset output voltages.
/V Denotes an automotive qualified part.
Note: Devices are also available in a lead(Pb)-free/RoHS-
compliant package. Specify lead-free by adding “+” to the part
number when ordering.
Typical Operating Circuit
Pin Configuration
TOP VIEW
IN
OUT
OUT
OUT
OUT
RST
SET
N.C.
IN
1
2
3
4
5
6
7
8
16 N.C.
15 OUT
14 OUT
13 OUT
12 OUT
11 SET
10 GND
IN
IN
OUT
OUT
MAX1793
IN
IN
C
C
IN
IN
MAX1793
IN
IN
ON
SHDN
RST
SHDN
N.C.
OFF
RESET
OUTPUT
9
N.C.
EP
GND
TSSOP
________________________________________________________________ Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
Low-Dropout, Low I , 1A Linear Regulator
Q
ABSOLUTE MAXIMUM RATINGS
Storage Temperature Range.............................-65°C to +150°C
IN, SHDN, RST to GND ............................................-0.3V to +6V
Lead Temperature (soldering, 10s) .................................+300°C
Soldering Temperature (reflow) .......................................+260°C
Soldering Temperature (reflow)
OUT, SET to GND........................................-0.3V to (V + 0.3V)
Output Short-Circuit Duration ............................................Infinite
IN
Continuous Power Dissipation (T = +70°C)
A
Lead(Pb)-Free Packages..............................................+260°C
Packages Containing Lead(Pb)....................................+240°C
TSSOP-EP (derate 19mW/°C above +70°C).....................1.5W
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature......................................................+150°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
MAX1793
ELECTRICAL CHARACTERISTICS
(V = V
+ 0.5V or V = 2.5V (whichever is greater), SHDN = IN, T = +0°C to +85°C, unless otherwise noted. Typical values
IN
OUT(NOM)
IN
A
are at T = +25°C.)
A
PARAMETER
SYMBOL
CONDITIONS
MIN
2.5
2.0
-1
TYP
MAX
5.5
UNITS
Input Voltage
V
V
V
V
IN
IN
Input Undervoltage Lockout
2.3
Preset V
≥ 2.5V
+1
OUT
OUT
T
= +85°C,
= 250mA
A
I
OUT
Preset V
< 2.5V
-1.5
-2
+1.5
+2
Output Voltage Accuracy
(Preset Mode, SET = GND)
T
A
= 0°C to +85°C, I
= 0°C to +85°C, I
= 250mA
ꢀ
OUT
T
A
= 1mA to 1A,
OUT
-3
+3
V
> V
+ 0.5V
IN
OUT
T
T
= +85°C, I
= 250mA, V = 3V
1.229
1.219
1.212
1.250
1.271
1.281
1.288
A
OUT
IN
SET Voltage Threshold
(For Adjustable Output)
= 0°C to +85°C, I
= 250mA, V = 3V
IN
V
V
A
OUT
T = 0°C to +85°C, I
A
= 1mA to 1A, V = 3V
IN
OUT
Adjustable Output Voltage
Range
1.25
5
Maximum Output Current
Short-Circuit Current Limit
I
Continuous, V ≥ 3V
1
A
OUT
IN
RMS
I
V
= 0V, V ≥ 3V
1.1
1.8
2.8
3.3
A
LIM
OUT
IN
V
V
within 4ꢀ of nominal output voltage,
= 5.5V
OUT
In-Regulation Current Limit
A
IN
SET Pin Dual Mode Threshold
SET Input Bias Current
Ground Current
50
150
100
200
350
450
mV
nA
µA
I
V
= +1.25V
= 100µA
SET
SET
I
I
125
210
270
GND
OUT
MAX1793-33, -50
MAX1793-25
I
= 1A,
OUT
Dropout Voltage (Note 1)
Line Regulation
V
- V
mV
IN
OUT
SET = GND
V
from (V
+ 0.1V) to +5.5V,
IN
OUT
∆V
∆V
-0.15
0
+0.15
ꢀ/V
ꢀ
LNR
LDR
I
= 5mA, SET = GND
OUT
Load Regulation
I
= 100µA to 1A
0.7
115
0.1
OUT
Output Voltage Noise
Shutdown Supply Current
10Hz to 1MHz, C
= 6.8µF (ESR < 0.1Ω)
µV
RMS
OUT
I
SHDN = GND, V = +5.5V
16
µA
OFF
IN
Output Pulldown Resistance in
Shutdown
SHDN = GND
5
kΩ
2
_______________________________________________________________________________________
Low-Dropout, Low I , 1A Linear Regulator
Q
MAX1793
ELECTRICAL CHARACTERISTICS (continued)
(V = V
+ 0.5V or V = 2.5V (whichever is greater), SHDN = IN, T = +0°C to +85°C, unless otherwise noted. Typical values
IN
OUT(NOM)
IN
A
are at T = +25°C.)
A
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
V
1.6
IH
SHDN Input Threshold
+2.5V < V < +5.5V
V
IN
V
0.6
1
IL
SHDN Input Bias Current
RST Output Low Voltage
I
SHDN = GND or IN
0.01
µA
V
SHDN
VOL
0.1
I
= 1mA
SINK
Operating Voltage Range for
RST Valid
V
I
= 100µA
= +5.5V
1.0
5.5
1
SINK
RST Output High Leakage
V
0.01
94
µA
RST
RST Trip Level Referred to
Rising edge
90
96
ꢀ V
OUT
Nominal V
OUT
RST Release Delay
Rising edge
1.5
4.0
8.0
ms
°C
Thermal Shutdown Temperature
T
Typical thermal hysteresis = 20°C
170
SHDN
ELECTRICAL CHARACTERISTICS
(V = V
+ 0.5V or V = 2.5V (whichever is greater), SHDN = IN, T = -40°C to +85°C, unless otherwise noted.) (Note 2)
IN
OUT(NOM)
IN
A
PARAMETER
SYMBOL
CONDITIONS
MIN
2.5
TYP
MAX
5.5
UNITS
V
Input Voltage
V
V
IN
V
Input Undervoltage Lockout
2.0
2.3
IN
I
I
I
I
= 250mA
-2.5
-3.2
1.216
1.210
2.5
OUT
OUT
OUT
OUT
Output Voltage Accuracy
(preset mode, SET = GND)
ꢀ
V
= 1mA to 1A, V > V
IN
+ 0.5V
3.2
OUT
= 250mA, V = 3V
IN
1.284
1.290
SET Voltage Threshold
(for adjustable output)
= 1mA to 1A, V = 3V
IN
Adjustable Output Voltage
Range
1.25
5
V
I
Continuous, V ≥ 3V
A
Maximum Output Current
Short-Circuit Current Limit
1
OUT
IN
RMS
I
V
= 0V, V ≥ 3V
1.1
3.3
150
100
200
350
450
A
LIM
OUT
IN
SET Pin Dual Mode Threshold
SET Input Bias Current
Ground Current
50
mV
nA
µA
I
V
I
= +1.25V
= 100µA
SET
SET
I
GND
OUT
OUT
V
V
-
MAX1793-33, -50
MAX1793-25
IN
I
= 1A,
Dropout Voltage (Note 1)
mV
OUT
SET = GND
V
from (V
= 5mA, SET = GND
+ 0.1V) to +5.5V,
IN
OUT
∆V
Line Regulation
-0.15
1.6
0.15
16
ꢀ/V
µA
V
LNR
I
OUT
I
SHDN = GND, V = +5.5V
Shutdown Supply Current
SHDN Input Threshold
OFF
IN
V
IH
+2.5V < V < +5.5V
IN
V
0.6
1
IL
I
SHDN Input Bias Current
RST Output Low Voltage
SHDN = GND or IN
µA
V
S H D N
V
I
= 1mA
0.1
OL
SINK
_______________________________________________________________________________________
3
Low-Dropout, Low I , 1A Linear Regulator
Q
ELECTRICAL CHARACTERISTICS (continued)
(V = V
+ 0.5V or V = 2.5V (whichever is greater), SHDN = IN, T = -40°C to +85°C, unless otherwise noted.) (Note 2)
IN
OUT(NOM)
IN
A
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
5.5
1
UNITS
V
Operating Voltage Range for
RST Valid
I
= 10µA
= +5.5V
1.0
SINK
V
RST Output High Leakage
µA
RST
RST Trip Level Referred to
MAX1793
ꢀ V
Rising edge
90
96
OUT
Nominal V
OUT
RST Release Delay
Note 1: Dropout voltage is defined as V - V
Rising edge
, when V
1.5
8.0
ms
is 100mV below the value of V
measured when V = V
OUT(NOM)
OUT(NOM)
> 3.3V: Typical Dropout = 210mV;
+
OUT(NOM)
OUT(NOM)
IN
OUT
OUT
OUT
IN
0.5V. Since the minimum input voltage is 2.5V, this specification in only meaningful when V
≥2.5V. For V
x 75mV/V; Guaranteed
between 2.5V and 3.3V, use the following equations: Typical Dropout = 210mV + (3.3V - V
Maximum Dropout = 350mV + (3.3V - V x 125mV/V. For V
OUT(NOM)
OUT(NOM)
Guaranteed Maximum Dropout = 350mV.
Note 2: Specifications to T = -40°C are guaranteed by design and not production tested.
A
Typical Operating Characteristics
(Circuit of Figure 2, V = +5V, V
= V , V
= +3.3V, T = +25°C, unless otherwise noted.)
SHDN
IN
IN OUT
A
OUTPUT VOLTAGE vs. TEMPERATURE
OUTPUT VOLTAGE vs. INPUT VOLTAGE
OUTPUT VOLTAGE vs. LOAD CURRENT
3.305
3.303
3.320
3.315
3.310
3.305
3.300
3.295
3.290
3.285
3.280
3.275
3.270
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
I
= 250mA
OUT
I
= 0
OUT
I
= 1A
OUT
3.301
3.299
3.297
3.295
3.293
-40
-20
0
20
40
60
80
1
10
100
1000
0
1
2
3
4
5
TEMPERATURE (°C)
LOAD CURRENT (mA)
INPUT VOLTAGE (V)
GROUND CURRENT vs. INPUT VOLTAGE
= 1A
GROUND CURRENT vs. TEMPERATURE
GROUND CURRENT vs. LOAD CURRENT
250
200
150
100
50
210
200
190
180
170
160
150
140
130
120
110
250
225
200
175
150
125
100
75
I
= 250mA
I
OUT
OUT
I
= 0
OUT
I
= 0
OUT
50
25
0
0
0
1
2
3
4
5
-40
-20
0
20
40
60
80
1
10
100
1000
INPUT VOLTAGE (V)
LOAD CURRENT (mA)
TEMPERATURE (°C)
4
_______________________________________________________________________________________
Low-Dropout, Low I , 1A Linear Regulator
Q
MAX1793
Typical Operating Characteristics (continued)
(Circuit of Figure 2, V = +5V, V
= V , V
= +3.3V, T = +25°C, unless otherwise noted.)
A
SHDN
IN
IN OUT
POWER-SUPPLY REJECTION RATIO
OUTPUT NOISE SPECTRAL DENSITY
vs. FREQUENCY
vs. FREQUENCY
DROPOUT VOLTAGE vs. LOAD CURRENT
60
50
40
30
20
10
0
10
300
250
200
150
100
50
I
= 250mA
OUT
1
0.1
I
= 250mA
0.1
OUT
0.01
0
0.01
0.1
1
10
100
1000
0.01
1
10
100
1000
0
200 400 600 800 1000 1200
LOAD CURRENT (mA)
FREQUENCY (kHz)
FREQUENCY (kHz)
OUTPUT NOISE vs. LOAD CURRENT
LINE-TRANSIENT RESPONSE
MAX1793 toc11
140
120
100
80
5V
V
IN
3.4V
60
V
OUT
40
10mV/div
AC-COUPLED
20
I
= 100mA
OUT
0
0.001
0.01
0.1
1
100µs/div
LOAD CURRENT (A)
LOAD-TRANSIENT RESPONSE
OUTPUT NOISE
MAX1793 toc12
MAX1793 toc13
1A
I
OUT
100mA
100µV/div
20mV/div
AC-COUPLED
V
OUT
40µs/div
4ms/div
_______________________________________________________________________________________
5
Low-Dropout, Low I , 1A Linear Regulator
Q
Typical Operating Characteristics (continued)
(Circuit of Figure 2, V = +5V, V
IN
= V , V
= +3.3V, T = +25°C, unless otherwise noted.)
SHDN
IN OUT A
RESET OUTPUT RESPONSE
SHUTDOWN RESPONSE
MAX1793 toc15
MAX1793 toc14
V
V
IN
MAX1793
OUT
5V/div
2V/div
2V/div
2V/div
5V/div
V
OUT
V
SHDN
RST
I
= 100mA
OUT
1ms/div
40µs/div
Pin Description
PIN
NAME
FUNCTION
1, 8, 9, 16
N.C.
No Connection. Not internally connected.
Regulator Input. Supply voltage ranges from +2.5V to +5.5V. Bypass with a 4.7µF capacitor to GND
(see the Capacitor Selection and Regulator Stability). These inputs are internally connected, but they
also must be externally connected for proper operation.
2–5
6
IN
Reset Output. Open-drain output is low when V
is 6ꢀ below its nominal value. RST remains low
OUT
RST
while the output voltage (V
) is below the reset threshold and for at least 4ms after V
OUT
rises above
OUT
the reset threshold. Connect a 100kΩ pullup resister to OUT to obtain an output voltage.
Active-Low Shutdown Input. A logic-low disables the output and reduces the supply current to 0.1µA.
In shutdown, the RST output is low and OUT is pulled low through an internal 5kΩ resistance. Connect
SHDN to IN for normal operation.
7
SHDN
Ground. This pin and the exposed pad also function as a heatsink. Solder both to a large pad or to the
circuit-board ground plane to maximize power dissipation.
10
11
GND
SET
OUT
EP
Voltage-Setting Input. Connect to GND to select the factory-present output voltage. Connect SET to an
external resistor-divider for adjustable-output operation.
Regulator Output. Bypass with a 6.8µF, low-ESR capacitor to GND. Connect all OUT pins together at
the IC.
12–15
—
Exposed Pad. Connect to the ground plane. EP also functions as a heatsink. Solder to the circuit-board
ground plane to maximize thermal dissipation.
6
_______________________________________________________________________________________
Low-Dropout, Low I , 1A Linear Regulator
Q
MAX1793
lower, allowing more current to pass and increase the
Detailed Description
output voltage. If the feedback voltage is high, the pass
The MAX1793 features Dual Mode™ operation, allow-
transistor’s gate is pulled up, allowing less current to
ing a fixed output or an adjustable output from +1.25V
to +5V. The regulators are guaranteed to supply 1A of
output current.
pass to the output. The low V
comparator senses
OUT
when the feedback voltage has dropped 6ꢀ below its
expected level, causing RST to go low.
As Figure 1 shows, the device consists of a +1.25V ref-
erence, error amplifier, MOSFET driver, p-channel pass
transistor, internal feedback voltage-divider, Dual Mode
comparator, and 4ms reset output.
The output voltage is fed back through either an inter-
nal resistor-divider connected to OUT or an external
resistor network connected to SET. The Dual Mode
comparator examines V
and selects the feedback
SET
The +1.25V reference is connected to the inverting
input of the error amplifier. The error amplifier com-
pares this reference with the selected feedback voltage
and amplifies the difference. The MOSFET driver reads
the error signal and applies the appropriate drive to the
p-channel transistor. If the feedback voltage is lower
than the reference, the pass transistor’s gate is pulled
path. If V
is below 50mV, the internal feedback path
is used and the output is regulated to the factory-preset
SET
voltage.
Dual Mode is a trademark of Maxim Integrated Products, Inc.
IN
SHUTDOWN
THERMAL
SENSOR
MOSFET DRIVER
WITH FOLDBACK
CURRENT LIMIT
ERROR AMP
PMOS
SHUTDOWN
LOGIC
SHDN
OUT
94% V
OUT
DETECTOR
4ms DELAY TIMER
IN
RST
NMOS
OUT
1.25V
REFERENCE
1175mV
4ms
SET
R1
MAX1793
100mV
DUAL MODE
COMPARATOR
R2
GND
Figure 1. Functional Diagram
_______________________________________________________________________________________
7
Low-Dropout, Low I , 1A Linear Regulator
Q
Internal p-Channel Pass Transistor
Shutdown
The MAX1793 features a 1A p-channel MOSFET pass
transistor. Unlike similar designs using pnp pass tran-
sistors, p-channel MOSFETs require no base drive,
which reduces quiescent current. pnp-based regula-
tors also waste considerable current in dropout when
the pass transistor saturates and use high base-drive
currents under large loads. The MAX1793 does not suf-
fer from these problems and consumes only 225µA of
quiescent current under heavy loads, as well as in
dropout.
A logic-low on SHDN disables the MAX1793. In shut-
down, the pass transistor, control circuitry, reference,
and all internal circuits are turned off, reducing supply
current to typically 0.1µA. Connect SHDN to IN for nor-
mal operation. In shutdown, RST goes low and OUT is
discharged to GND with a 5kΩ internal resistance.
RST Comparator
indicator that asserts
MAX1793
The MAX1793 features a low V
OUT
when the output voltage falls out of regulation. The
open-drain RST output goes low when OUT falls 6ꢀ
below its nominal output voltage. RST remains low for
4ms after OUT has returned to its nominal value. A
100kΩ pullup resistor from RST to a suitable logic sup-
ply voltage (typically OUT) provides a logic control sig-
nal. RST can be used as a power-on-reset (POR) signal
to a microcontroller or can drive an external LED to indi-
cate power failure. RST is low during shutdown.
Output Voltage Selection
The MAX1793 features Dual Mode operation. In preset
voltage mode, the output of the MAX1793 is set to an
internally trimmed voltage (see the Ordering
Information). Select this mode by connecting SET to
GND (Figure 2).
In adjustable mode, an output is selected between
+1.25V and +5V using two external resistors connected
as a voltage-divider to SET (Figure 3). The output volt-
age is determined by the following equation:
Current Limiting
The MAX1793 features a current limit that monitors the
pass transistor, typically limiting short-circuit output
current to 1.8A. The current limit is increased to
approximately 2.8A when the output voltage is in regu-
lation, improving performance with large transient
loads. The output can be shorted to ground for an
indefinite period of time without damaging the device.
V
OUT
= V
[1 + (R1/R2)]
SET
where V
= +1.25V. To simplify resistor selection:
SET
R1 = R2 [(V
/V
) – 1]
OUT SET
Since the input bias current at SET is less than 100nA,
large resistance values can be used for R1 and R2 to
minimize power consumption without losing efficiency.
Up to 125kΩ is acceptable for R2.
In preset voltage mode, the impedance from SET to
GND should be less than 10kΩ. Otherwise, spurious
conditions could cause the voltage at SET to exceed
the 50mV dual-mode threshold.
Thermal-Overload Protection
Thermal-overload protection limits total power dissipa-
tion in the MAX1793. When the junction temperature
exceeds T = +170°C, a thermal sensor turns off the
J
pass transistor, allowing the IC to cool. The thermal sen-
sor turns the pass transistor on once the IC’s junction
temperature drops approximately 20°C. Continuous
short-circuit conditions will result in a pulsed output.
IN
OUT
OUT
OUT
OUT
RST
IN
OUT
OUT
OUT
OUT
RST
SET
IN
IN
IN
= 4.7µF
OUT
= 6.8µF
MAX1793
IN
IN
OUT
C = 6.8µF
OUT
MAX1793
IN
C
IN
C
OUT
C
= 4.7µF
IN
R1
R2
IN
IN
ON
SHDN
GND
ON
OFF
RESET
OUTPUT
SHDN
OFF
RESET
OUTPUT
SET
GND
Figure 2. Typical Operating Circuit with Preset Output Voltage
Figure 3. Typical Operating Circuit with Adjustable Output
Voltage
8
_______________________________________________________________________________________
Low-Dropout, Low I , 1A Linear Regulator
Q
MAX1793
Thermal-overload protection is designed to safeguard
the MAX1793 in the event of fault conditions. For con-
tinuous operation, do not exceed the absolute maxi-
MAXIMUM OUTPUT CURRENT vs.
INPUT-OUTPUT DIFFERENTIAL VOLTAGE
mum junction-temperature rating of T = +150°C.
J
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
MAXIMUM CONTINUOUS CURRENT
Operating Region and Power Dissipation
Maximum power dissipation of the MAX1793 depends
on the thermal resistance of the case and circuit board,
the temperature difference between the die junction
and ambient air, and the rate of air flow. The power dis-
T = +25°C
A
sipated by the device is: P = I
(V – V
). The
OUT
OUT
IN
resulting maximum power dissipation is:
T = +50°C
A
P
MAX
= [(T – T )/(θ + θ )]
T = +70°C
A
J(MAX)
A
JC
CA
T
= +150°C
J(MAX)
where (T
– T ) is the temperature difference
A
J(MAX)
0
1
2
3
4
5
6
between the maximum allowed die junction (+150°C) and
INPUT-OUTPUT DIFFERENTIAL VOLTAGE (V)
the surrounding air, θ (junction-to-case) is the thermal
resistance of the package chosen, and θ is the thermal
JC
CA
resistance from the case through the PCB, copper traces,
and other materials to the surrounding air. Figure 4 shows
allowable power dissipation for typical PCBs at +25°C,
+50°C, and +70°C ambient temperatures.
Figure 4. Power Operating Region: Maximum Output Current
vs. Input-Output Differential Voltage
Noise, PSRR, and Transient Response
The MAX1793 TSSOP-EP package features an exposed
thermal pad on its underside. This pad lowers the ther-
mal resistance of the package by providing a direct heat
conduction path from the die to the PCB. Additionally,
the ground pin (GND) also channels heat. Connect the
exposed thermal pad and GND to circuit ground by
using a large pad (minimum 1in2 recommended), or mul-
tiple vias to the ground plane.
The MAX1793 output noise is typically 115µV
during
RMS
normal operation. This is suitably low for most applica-
tions. See the output noise plot in the Typical Operating
Characteristics.
The MAX1793 is designed to achieve low dropout volt-
age and low quiescent current in battery-powered sys-
tems while still maintaining good noise, transient
response, and AC rejection. See the Typical Operating
Characteristics for a plot of Power-Supply Rejection
Ratio (PSRR) vs. Frequency. When operating from very
noisy sources, supply noise rejection and transient
response can be improved by increasing the values of
the input and output capacitors and employing passive
postfiltering.
Applications Information
Capacitor Selection
and Regulator Stability
Capacitors are required at the input and output of the
MAX1793. Connect a 4.7µF capacitor between IN and
ground (C ) and a 6.8µF capacitor between OUT and
IN
ground (C
). C serves only to lower the source
IN
OUT
Input-Output (Dropout) Voltage
A regulator’s minimum input-to-output voltage differential
(dropout voltage) determines the lowest usable supply
voltage. In battery-powered systems, this determines the
useful end-of-life battery voltage. Since a p-channel
MOSFET is used as the pass device, dropout voltage is
impedance of the input supply and may be smaller than
4.7µF when the MAX1793 is powered from regulated
power supplies or low-impedance batteries.
The output capacitor’s equivalent series resistance (ESR)
affects stability and output noise. C
ESR should be
OUT
the product of R
and load current (see the
DS(ON)
0.5Ω or less to ensure stability and optimum transient
response. Surface-mount ceramic capacitors have very
low ESR and are commonly available in values up to
10µF. Other low-ESR (< 0.5Ω) capacitors, such as sur-
face-mount tantalum or OS-CON, may also be used.
Electrical Characteristics and Dropout Voltage vs. Load
Current in the Typical Operating Characteristics). The
MAX1793 operating current typically remains below
225µA in dropout.
Connect C and C
as close to the IC as possible to
OUT
IN
minimize the impact of PCB trace inductance.
_______________________________________________________________________________________
9
Low-Dropout, Low I , 1A Linear Regulator
Q
Package Information
Ordering Information (continued)
For the latest package outline information and land patterns
(footprints), go to www.maxim-ic.com/packages. Note that a
“+”, “#”, or “-” in the package code indicates RoHS status only.
Package drawings may show a different suffix character, but
the drawing pertains to the package regardless of RoHS status.
†
TEMP
RANGE
PIN-
PACKAGE
V
OUT
(V)
PART
MAX1793EUE-25 -40°C to +85°C 16 TSSOP-EP* 2.5 or Adj
MAX1793EUE-20 -40°C to +85°C 16 TSSOP-EP* 2.0 or Adj
MAX1793EUE-18 -40°C to +85°C 16 TSSOP-EP* 1.8 or Adj
LAND
PACKAGE
TYPE
16 TSSOP-EP
PACKAGE
CODE
OUTLINE NO.
21-0108
PATTERN NO.
MAX1793
90-0120
U16E-3
MAX1793EUE-15 -40°C to +85°C 16 TSSOP-EP* 1.5 or Adj
*EP = Exposed pad.
Contact factory for other preset output voltages.
/V Denotes an automotive qualified part.
†
Note: Devices are also available in a lead(Pb)-free/RoHS-
compliant package. Specify lead-free by adding “+” to the part
number when ordering.
10 ______________________________________________________________________________________
Low-Dropout, Low I , 1A Linear Regulator
Q
MAX1793
Revision History
REVISION
NUMBER
REVISION
DATE
PAGES
CHANGED
DESCRIPTION
0
1
2
8/00
11/00
9/09
Initial release
—
1–4, 7–9
1
Added output voltages and updated Electrical Characteristics.
Added the automotive version of the MAX1793.
Added lead-free options and updated soldering temperature and Pin
Description
3
1/12
1, 2, 6, 10
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits) shown in
the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
11 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2012 Maxim Integrated Products
Maxim is a registered trademark of Maxim Integrated Products, Inc.
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