MAXIM MAX8890EGCABK

19-2075; Rev 0; 7/01
Integrated Cellular RF-Section
Power-Management IC
The first LDO is intended to power the transmitter,
receiver, and synthesizer. The second LDO is intended
to power the TCXO, and high-power voltage-controlled
oscillators (VCOs). The third LDO is intended to power
the UHF offset VCO.
Each LDO has its own individual enable (ON/OFF) control to maximize design flexibility. The reference is powered on if any of the enable inputs (EN1, EN2, EN3) are
logic high. The high-accuracy output voltage of each
LDO is preset at an internally trimmed voltage (1.8V to
3.3V in 50mV increments). Each LDO is capable of supplying 100mA with a low 50mV dropout and is optimized for low noise and high crosstalk-isolation.
Designed with internal P-channel MOSFET pass transistors, the MAX8890’s low 180µA operating supply current is independent of load.
Other features include short-circuit and thermal overload protection. The MAX8890 is available in a compact, high-power, 12-pin 4mm ✕ 4mm QFN package
with a metal pad on the underside.
Applications
Cellular Handsets
Single-Cell Li+ Systems
3-Cell NiMH, NiCD, or Alkaline Systems
Personal Digital Assistants (PDAs)
Standard Preset Output
Voltage Suffixes
SUFFIX
OUTPUT
VOLTAGE (V)
SUFFIX
OUTPUT
VOLTAGE (V)
A
3.30
H
2.75
B
3.00
J
2.70
D
2.90
K
2.50
F
2.85
L
2.00
G
2.80
M
1.80
*Nonstandard output voltages between 1.80V and 3.30V are
available in 50mV increments.
Features
♦ Three 100mA Low-Dropout Linear Regulators
♦ Low 50mV Dropout Voltage at 100mA
♦ ±1% Output Voltage Accuracy Over Temperature
♦ Preset 1.8V to 3.3V Output Voltages
(in 50mV Increments)
♦ Low 45µVRMS Output Voltage Noise
♦ Low 180µA Operating Supply Current
♦ 2.5V to 5.5V Input Voltage Range
♦ 67dB PSRR
♦ 10µVp-p Channel-to-Channel Crosstalk
♦ Short-Circuit Protection
♦ Thermal Overload Protection
♦ 0.01µA Shutdown Current
♦ Tiny 12-Pin 4mm x 4mm QFN Package
Ordering Information
PART
TEMP. RANGE
PIN-PACKAGE
MAX8890EGCxyz*
-40°C to +85°C
12 (4 x 4) QFN
*Each preset output voltage of these devices is factory
trimmed to one of ten voltages. Replace “xyz” with the letters
corresponding to the desired output voltages (see Standard
Preset Output Voltage Suffixes table), where the three letter
suffix corresponds to the following output voltages: “x” =
VOUT1, “y” = VOUT2, and “z” = VOUT3.
Note: There are five standard versions available (see Standard
Versions table). Sample stock is generally held on standard
versions only. Standard versions have an order increment
requirement of 2500 pieces. Nonstandard versions have an
order increment requirement of 10,000 pieces. Contact the
factory for availability of nonstandard versions.
Typical Operating Circuit
INPUT
IN1
OUT1
OUTPUT #1
IN2
OUT2
OUTPUT #2
IN3
OUT3
OUTPUT #3
EN1
BP
MAX8890
ON
OFF
EN2
EN3
GND
Standard Versions table and Pin Configuration appear at
end of data sheet.
________________________________________________________________ Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
1
MAX8890
General Description
The MAX8890 is a power-management IC intended for
cellular handsets using a single lithium-ion (Li+) cell
battery with input voltages from +2.5V to +5.5V. The IC
contains three identical, low-noise, low-dropout (LDO)
linear regulators to provide all of the supply voltage
requirements for the RF portion of the handset.
MAX8890
Integrated Cellular RF-Section
Power-Management IC
ABSOLUTE MAXIMUM RATINGS
IN_, EN_ to GND.......................................................-0.3V to +6V
OUT_, BP to GND ......................................-0.3V to (VIN_ + 0.3V)
Output Short-Circuit Protection (Note A) .......................indefinite
Continuous Power Dissipation (TA = +70°C)
12-Pin 4 x 4 QFN (derate 16.9mW/°C above +70°C) .......1349mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Note A: As long as the maximum continuous power dissipation rating is not exceeded, the output may be shorted indefinitely.
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.
ELECTRICAL CHARACTERISTICS
(VIN_ = 3.6V, EN_ = IN_, CIN = 6.8µF, COUT_ = 2.2µF, CBP = 0.01µF, all ceramic capacitors TA = 0°C to +85°C, unless otherwise
noted. Typical values are at TA = +25°C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
5.5
V
2.45
V
GENERAL
Input Voltage
Input Undervoltage Lockout
Threshold
VIN_
VUVLO
2.5
Rising and falling edge
2.10
Input Undervoltage Hysteresis
2.25
45
mV
SUPPLY CURRENT
Quiescent Supply Current
IQ
Shutdown Supply Current
IOUT_ = 0
180
330
µA
EN_ = OUT_ = GND
0.01
10
µA
LINEAR REGULATORS
Output Voltage Accuracy
Current Limit
Output Pulldown Resistance
Dropout Voltage (Note 1)
VOUT_
ILIM
ROUT_
VIN_ VOUT_
VIN_ = 0.5V + the
highest of
(VOUT1, VOUT2, or
VOUT3),
IOUT_ = 1mA to
100mA
TA = +85°C
-1
+1
%
TA = 0°C +85°C
OUT_ = GND
EN_ = GND
-2
+2
120
250
500
mA
3
5
8
kΩ
IOUT_ = 1mA
1
IOUT_ = 50mA
25
IOUT_ = 100mA
50
mV
100
Line Regulation
VIN_ = (VOUT_+ 0.1V) to 5.5V for VOUT_ ≥
2.4V, or VIN_ = 2.5V to 5.5V for VOUT_ <
2.4V, IOUT = 1mA
Output Voltage Noise
10Hz to 100kHz, COUT_ = 10µF ceramic,
VOUT_ = 2.8V, IOUT_ = 10mA
45
µVRMS
Output Voltage PSRR
100Hz, COUT_ = 2.2µF ceramic,
IOUT_ = 10mA
67
dB
Channel-to-Channel Isolation
10kHz, COUT_ = 2.2µF ceramic,
IOUT_ = 10mA
64
dB
2
-0.15
+0.15
_______________________________________________________________________________________
%/V
Integrated Cellular RF-Section
Power-Management IC
(VIN_ = 3.6V, EN_ = IN_, CIN = 6.8µF, COUT_ = 2.2µF, CBP = 0.01µF, all ceramic capacitors TA = 0°C to +85°C, unless otherwise
noted. Typical values are at TA = +25°C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
ENABLE LOGIC CONTROL
EN_ Input Threshold
VEN_
2.5V ≤ VIN_ ≤ 5.5V
0.4
1.6
V
EN_ Input Bias Current
IEN_
VEN_ = 5.5V or 0, TA = +85°C
-1
+1
µA
THERMAL PROTECTION
Thermal Shutdown Temperature
Thermal Shutdown Hysteresis
TSHDN
Rising temperature
∆TSHDN
160
°C
15
°C
ELECTRICAL CHARACTERISTICS
(VIN_ = 3.6V, EN_ = IN_, CIN = 6.8µF, COUT_ = 2.2µF, CBP = 0.01µF, all ceramic capacitors TA = -40°C to +85°C, unless otherwise
noted.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
MAX
UNITS
2.5
5.5
V
2.10
2.45
V
GENERAL
Input Voltage
VIN_
Input Undervoltage Lockout
Threshold
VUVLO
Rising and Falling edge
SUPPLY CURRENT
Quiescent Supply Current
IQ
Shutdown Supply Current
IOUT_ = 0
330
µA
EN_ = OUT_ = GND
10
µA
-2
+2
%
110
500
mA
3
8
kΩ
100
mV
-0.15
+0.15
%/V
LINEAR REGULATORS
Output Voltage Accuracy
Current Limit
VOUT_
ILIM
VIN_ = 0.5V + the highest of (VOUT1, VOUT2,
or VOUT3), IOUT_ = 1mA to 100mA
OUT_ = GND
Output Pulldown Resistance
ROUT_
EN_ = GND
Dropout Voltage (Note 1)
VIN_ VOUT_
IOUT_ = 100mA
VIN_ = (VOUT_+ 0.1V) to 5.5V for VOUT_ ≥
2.4V, or VIN_ = 2.5V to 5.5V for VOUT_ <
2.4V, IOUT = 1mA
Line Regulation
ENABLE LOGIC CONTROL
EN_ Input Threshold
VEN_
2.5V ≤ VIN_ ≤ 5.5V
0.4
1.6
V
EN_ Input Bias Current
IEN_
VEN_ = 5.5V or 0, TA = +85°C
-1
1
µA
Note 1: The Dropout Voltage is defined as VIN_ - VOUT_, when VOUT_ is 100mV below the set output voltage (the value of VOUT_ for
VIN_ = VOUT_ + 500mV). Since the minimum input voltage range is 2.5V, this specification is only meaningful when the set
output voltage exceeds 2.7V (VOUT_(NOM) ≥ 2.7V).
Note 2: Specifications to -40°C are guaranteed by design, not production tested.
_______________________________________________________________________________________
3
MAX8890
ELECTRICAL CHARACTERISTICS (continued)
Typical Operating Characteristics
(Circuit of Figure 1, MAX8890EGCGGG, VIN = 3.3V, EN_ = IN_, TA = +25°C, unless otherwise noted.)
OUTPUT VOLTAGE
vs. LOAD CURRENT
1.5
1.0
0.5
2.82
OUTPUT VOLTAGE (V)
2.0
2.83
MAX8890 toc02
2.82
OUTPUT VOLTAGE (V)
2.5
OUTPUT VOLTAGE (V)
2.83
MAX8890 toc01
3.0
OUTPUT VOLTAGE
vs. TEMPERATURE
2.81
2.80
2.79
MAX8890 toc03
OUTPUT VOLTAGE
vs. INPUT VOLTAGE
2.81
2.80
2.79
2.78
2.78
2.77
2.77
IOUT = 100mA
IOUT = NO LOAD
4
5
0
60
80
GROUND-PIN CURRENT
vs. INPUT VOLTAGE
MAX8890 toc04
TA = +25°C
50
TA = +85°C
30
TA = -40°C
20
100
160
140
IOUT1 = 100mA
120
100
0
80
60
20
40
60
80
IOUT = NO LOAD
2
3
4
5
6
0
40
70
ISOLATION (dB)
50
40
10
50
85
100
50
40
30
20
CIN = 1µF + 0.1µF
IOUT = 10mA
LOW-IMPEDANCE INPUT
IOUT1 = 100mA SINUSOIDAL LOAD
IOUT3 = 10mA
10
0
60
80
60
20
IOUT1 = 100mA
ONLY ONE OUTPUT ENABLED
(EN1 = IN, EN2 = EN3 = GND)
60
80
MAX8890 toc08
70
PSRR (dB)
70
TEMPERATURE (°C)
20
CHANNEL-TO-CHANNEL ISOLATION
30
35
ONLY ONE OUTPUT ENABLED
(EN1 = IN, EN2 = EN3 = GND)
LOAD CURRENT (mA)
80
MAX8890 toc07
80
10
65
POWER-SUPPLY REJECTION RATIO
90
-15
70
50
1
60
-40
75
55
GROUND-PIN CURRENT
vs. TEMPERATURE
60
80
60
0
100
85
85
INPUT VOLTAGE (V)
110
60
90
20
LOAD CURRENT (mA)
120
35
95
40
100
10
100
0
0
-15
GROUND-PIN CURRENT
vs. LOAD CURRENT
ONLY ONE OUTPUT ENABLED
(EN1 = IN, EN2 = EN3 = GND)
180
-40
TEMPERATURE (°C)
200
10
4
40
DROPOUT VOLTAGE
vs. LOAD CURRENT
60
40
20
LOAD CURRENT (mA)
70
DROPOUT VOLTAGE (mV)
6
MAX8890 toc06
3
MAX8890 toc09
2
INPUT VOLTAGE (V)
MAX8890 toc05
1
GROUND-PIN CURRENT (µA)
0
GROUND-PIN CURRENT (µA)
0
GROUND-PIN CURRENT (µA)
MAX8890
Integrated Cellular RF-Section
Power-Management IC
0
0.01
0.1
1
10
FREQUENCY (kHz)
100
1000
0.1
1
10
FREQUENCY (kHz)
_______________________________________________________________________________________
100
1000
Integrated Cellular RF-Section
Power-Management IC
LOAD TRANSIENT
LINE TRANSIENT RESPONSE
LOAD TRANSIENT NEAR DROPOUT
MAX8890 toc10
MAX8890 toc12
MAX8890 toc11
4.0V
A
A
A
3.5V
B
B
20µs/div
STARTUP WAVEFORM
(CBP = 0.01µF)
LOW-IMPEDANCE INPUT
IOUT1 = 100mA SINUSOIDAL LOAD
IOUT3 = 10mA
MAX8890 toc13
1000
A. VIN = 3.5V to 4.0V, 200mV/div
B. VOUT_ = 2.8V, 2mV/div
IOUT = 100mA
A. IOUT_ = 1mA to 100mA, 50mA/div
B. VOUT_ = 2.8V, 20mV/div
VIN = 2.9V (VOUT_ + 100mV)
CROSSTALK VOLTAGE
CROSSTALK (µVp-p)
40µs/div
20µs/div
A. IOUT_ = 1mA to 100mA, 50mA/div
B. VOUT_ = 2.8V, 20mV/div
VIN = 3.3V (VOUT_ +500mV)
B
2.8V
STARTUP WAVEFORM
(CBP = 0.1µF)
MAX8890 toc14
MAX8890 toc15
A
A
B
B
C
C
100
10
1
0.1
1
10
100
FREQUENCY (kHz)
1000
20µs/div
A. VIN = 0 to 3.3V, 5V/div
B. VOUT_ = 2.8V, 2V/div
C. VBP = 1.25V, 1V/div
ROUT_ = 28Ω (100mA)
5ms/div
A. VIN = 0 to 3.3V, 5V/div
B. VOUT_ = 2.8V, 2V/div
C. VBP = 1.25V, 1V/div
ROUT_ = 28Ω (100mA)
_______________________________________________________________________________________
5
MAX8890
Typical Operating Characteristics (continued)
(Circuit of Figure 1, MAX8890EGCGGG, VIN = 3.3V, EN_ = IN_, TA = +25°C, unless otherwise noted.)
MAX8890
Integrated Cellular RF-Section
Power-Management IC
Typical Operating Characteristics (continued)
(Circuit of Figure 1, MAX8890EGCGGG, VIN = 3.3V, EN_ = IN_, TA = +25°C, unless otherwise noted.)
ENABLE WAVEFORM
(1ST OUTPUT)
ENABLE WAVEFORM
(2ND OUTPUT)
MAX8890 toc16
MAX8890 toc17
A
A
B
B
C
C
D
D
20µs/div
A. VEN1 = 0 to 3.3V, 5V/div
B. VOUT1 = 2.8V, ROUT1 = 28Ω (100mA), 2V/div
C. VBP = 1.25V, 1V/div
D. IIN, 200mA/div
VIN = 3.3V, EN2 = EN3 = GND, CBP = 0.01µF
20µs/div
A. VEN2 = 0 to 3.3V, 5V/div
B. VOUT2 = 2.8V, ROUT2 = 28Ω (100mA), 2V/div
C. VBP = 1.25V, 1V/div
D. IIN, 200mA/div
VIN = 3.3V, EN1 = IN, EN3 = GND, CBP = 0.01µF
Pin Description
6
PIN
NAME
FUNCTION
1
IN1
Regulator 1 Input. Supply voltage can range from 2.5V to 5.5V. Bypass with a capacitor to GND (see
Capacitor Selection and Regulator Stability).
2
IN2
Regulator 2 Input. Supply voltage can range from 2.5V to VIN1. Bypass with a capacitor to GND (see
Capacitor Selection and Regulator Stability).
3
OUT2
Regulator 2 Output. Sources up to 100mA. Bypass with a 2.2µF ceramic capacitor to GND.
4
EN1
Active-High Enable Input for Regulator 1. A logic low shuts down the first linear regulator. In shutdown,
OUT1 is pulled low through an internal 5kΩ resistor. Connect to IN1 for normal operation.
5
EN2
Active-High Enable Input for Regulator 2. A logic low shuts down the second linear regulator. In
shutdown, OUT2 is pulled low through an internal 5kΩ resistor. Connect to IN2 for normal operation.
6
EN3
Active-High Enable Input for Regulator 3. A logic low shuts down the third linear regulator. In
shutdown, OUT3 is pulled low through an internal 5kΩ resistor. Connect to IN3 for normal operation.
7
BP
8
GND
1.25V Voltage Reference Bypass Pin. Connect a 0.01µF ceramic bypass capacitor from BP to GND to
minimize the output noise. Make no other connection to this pin.
Ground. Connect both ground pins together externally, as close to the IC as possible.
Regulator 3 Input. Supply voltage can range from 2.5V to VIN1. Bypass with a capacitor to GND (see
Capacitor Selection and Regulator Stability).
9
IN3
10
OUT3
11
GND
Ground. Connect both ground pins together externally, as close to the IC as possible.
12
OUT1
Regulator 1 Output. Sources up to 100mA. Bypass with a 2.2µF ceramic capacitor to GND.
EXPOSED
PAD
GND
Ground. THE EXPOSED PAD AND ALL FOUR CORNER TABS ON THE QFN PACKAGE ARE
INTERNALLY CONNECTED TO GROUND. The exposed pad functions as a heatsink. Solder to a large pad
or to the circuit board ground plane to maximize power dissipation. Do not use as device ground.
Regulator 3 Output. Sources up to 100mA. Bypass with a 2.2µF ceramic capacitor to GND.
_______________________________________________________________________________________
Integrated Cellular RF-Section
Power-Management IC
IN1
OUT1
IN2
OUT2
CIN
4.7µF
OUTPUT #1
(1.8V TO 3.3V)*
COUT1
2.2µF
COUT2
2.2µF
MAX8890
IN3
OUT3
EN1
BP
MAX8890
INPUT
2.5V TO 5.5V
OUTPUT #2
(1.8V TO 3.3V)*
OUTPUT #3
(1.8V TO 3.3V)*
COUT3
2.2µF
ON
OFF
CBP
0.01µF
EN2
EN3
GND
*SEE THE Ordering Information AND
Preset Output Voltage Suffixes SECTIONS
Figure 1. Typical Application Circuit
Detailed Description
The MAX8890 is an RF power-management IC for a
cellular phone. The MAX8890 contains three low-noise,
low quiescent current, low-dropout, linear regulators for
powering the transmitter, receiver, synthesizer, TCXO,
and voltage controlled oscillators (VCOs). Each lowdropout linear regulator (LDO) supplies loads up to
100mA and is available with preset output voltages
from 1.8V to 3.3V in 50mV increments. Furthermore, the
MAX8890’s input voltage range of 2.5V to 5.5V is perfect for single-cell Li+ battery or 3-cell NiMH battery
applications.
As illustrated in Figure 2, each regulator consists of an
error amplifier, internal feedback resistive-divider, and
P-channel MOSFET pass transistor. The output voltage
feeds back through the internal resistive-divider connected to OUT_. This feedback voltage connects to the
error amplifier, which compares the feedback voltage
with the internal 1.25V reference voltage and amplifies
the difference. If the feedback voltage is lower than the
reference voltage, the pass-transistor gate is pulled
lower, which allows more current to flow to the output
and increases the output voltage. If the feedback voltage is too high, the pass-transistor gate is pulled up,
allowing less current to flow to the output.
Clear transmission and reception in a cellular phone
can only be achieved with a low-noise power supply.
Therefore, all three LDOs on the MAX8890 feature low
output voltage noise, high power-supply rejection
ratios, and excellent load and line regulation characteristics. Designed for single-cell Li+ battery applications
where a pulsed current demand is required from the
battery, each LDO is designed with 45µVRMS noise
from 10Hz to 100kHz and PSRR of 67dB.
The MAX8890 also features output current limiting
(short-circuit protection), a low-power shutdown mode,
and thermal overload protection.
Internal P-Channel Pass MOSFET
Each linear regulator features a 0.5Ω P-channel MOSFET pass transistor. Unlike similar designs using PNP
pass transistors, P-channel MOSFETs require no base
drive, which reduces the quiescent current. PNP based
regulators also waste considerable current in dropout
when the pass transistor saturates and use high basedrive currents under large loads. The MAX8890 does
not suffer from these problems and consumes only
180µA of quiescent current (all 3 regulators enabled).
Current Limit (Short-Circuit Protection)
The MAX8890 contains separate current-limit circuitry
for each linear regulator. The device monitors and controls the gate voltage of each pass transistor, limiting
the regulator’s output current to 250mA (typ). The output can be shorted to ground for an indefinite period of
time without damage to the part as long as the maximum continuous power dissipation rating is not
exceeded.
Output Voltage Selection
The MAX8890 is supplied with factory-set output voltages from 1.8V to 3.3V in 50mV increments. The threeletter part number suffix identifies the output voltage for
each regulator. For example, the MAX8890EGCAKM’s
output voltages are preset to 3.3V (V OUT1 ), 2.5V
(VOUT2), and 1.8V (VOUT3).
_______________________________________________________________________________________
7
MAX8890
Integrated Cellular RF-Section
Power-Management IC
LINEAR REGULATOR #1
IN1
RSENSE
OUT1
THERMAL
SHDN
ERROR
AMPLIFIER
CURRENT
LIMIT
CONTROL
LOCIC
IN1
EN1
BP
REF
1.25V
STARTUP
CIRCUITRY
GND
IN2
LINEAR REGULATOR #2
OUT2
EN2
IN3
LINEAR REGULATOR #3
OUT3
EN3
Figure 2. Functional Diagram
Enable
If any one of the three low-dropout linear regulators
(LDOs) is enabled, the internal 1.25V reference powers
up. Therefore, all three LDOs must be disabled to shut
down the internal reference, reducing the supply current to 0.01µA.
Pull EN_ low to enter shutdown. When any one of the
linear regulators is shutdown, the corresponding
MAX8890 output disconnects from the corresponding
input, and the output discharges through an internal
8
5kΩ resistor. The capacitance and load determine the
rate at which VOUT_ decays. Do not leave EN_ floating.
Connect EN_ to IN_ for normal operation. EN_ can be
pulled as high as 6V, regardless of the input and output
voltages.
Thermal Overload Protection
Thermal overload protection limits the MAX8890’s total
power dissipation in the event of fault conditions. Each
linear regulator has its own thermal shutdown circuitry.
_______________________________________________________________________________________
Integrated Cellular RF-Section
Power-Management IC
Applications Information
Capacitor Selection and Regulator
Stability
Capacitors are required at each input and each output
of the MAX8890 for stable operation over the full load
range and full temperature range. Connect a minimum
2.2µF ceramic capacitor between OUT_ and ground to
ensure stability and optimum transient response. Use
larger 10µF ceramic output capacitors for lower noise
requirements.
The input capacitor (CIN_) lowers the source impedance of the input supply, thereby reducing the input
noise and improving transient response. Connect a
minimum 1µF ceramic capacitance between each IN_
and ground. Place all input and output capacitors as
close to the MAX8890 as possible to minimize the
impact of PC board trace impedance. Because IN1
and IN2 are next to each other, they may easily share a
single 2.2µF or larger ceramic capacitor.
Surface-mount ceramic capacitors have very low ESR
and are commonly available in values up to 10µF.
However, note that some ceramic dielectrics exhibit
large capacitance and ESR variation with temperature.
Z5U and Y5V dielectrics may require a minimum 3.3µF
nominal output capacitance, especially with low temperature operation.
Noise, PSRR, and Transient Response
The MAX8890 is designed to operate with low dropout
voltages and low quiescent currents in battery-powered
systems while providing low noise, fast transient
response, and high AC rejection. See the Typical
Operating Characteristics for a plot of Power-Supply
Rejection Ratio (PSRR) vs. Frequency. When operating
from noisy sources, improved supply-noise rejection
and transient response can be achieved by increasing
the values of the input and output bypass capacitors
and through passive filtering techniques.
The MAX8890 load-transient response graphs (see
Typical Operating Characteristics) show two components of the output response: a DC shift from the output
impedance due to the load current change and the
transient response. Increasing the output capacitor’s
value and decreasing the ESR reduces the transient
under/overshoot.
Input-Output (Dropout) Voltage
A regulator’s minimum input-to-output voltage differential (dropout voltage) determines the lowest useable
input supply voltage. Once the linear regulator reaches
dropout, the series pass transistor is fully on and regulation ceases. The output voltage tracks the input voltage as the input voltage drops lower. Because the
MAX8890 uses P-channel MOSFET pass transistors, its
dropout voltage is a function of the MOSFET’s drain-tosource on-resistance (RDS(ON)) multiplied by the load
current (see Typical Operating Characteristics):
VDROPOUT = VIN_ - VOUT_ = RDS(ON) ✕ IOUT_
Reference Bypass Capacitor
An external bypass capacitor is connected to BP to
reduce the inherent reference noise. The capacitor
forms a lowpass filter in conjunction with an internal
network. Use a 0.01µF or greater ceramic capacitor
connected as close to BP as possible. Capacitance
values greater than 0.01µF will increase the startup
time. (See Typical Operating Characteristics for startup
waveforms.) For the lowest noise, increase the bypass
capacitor to 0.1µF. Values above 0.1µF provide no performance improvement and are therefore not recommended. Do not place any additional loading on this
reference bypass pin.
_______________________________________________________________________________________
9
MAX8890
When the junction temperature exceeds TJ = 160°C, a
thermal sensor activates the shutdown logic, disabling
the overheated regulator. The thermal sensor turns the
linear regulator on again after the regulator’s junction
temperature cools by 15°C, resulting in a pulsed output
during continuous thermal-overload conditions. For
continuous operation, do not exceed the absolute maximum junction-temperature rating of TJ = 150°C.
Integrated Cellular RF-Section
Power-Management IC
MAX8890
Pin Configuration
VERSION
TOP VIEW
IN1
IN2
TOP MARK
OUT1
GND
OUT3
MAX8890EGCAAA
AAAA
12
11
10
MAX8890EGCDDD
AAAC
MAX8890EGCGGG
AAAE
1
9
2
MAX8890
OUT2
Standard Versions
3
4
5
6
EN1
EN2
EN3
IN3
8
GND
7
BP
MAX8890EGCMMM
AAAJ
MAX8890EGCAKM
AAAK
Chip Information
TRANSISTOR COUNT: 1472
PROCESS: BiCMOS
4 ✕ 4 QFN
10
______________________________________________________________________________________
Integrated Cellular RF-Section
Power-Management IC
12, 16,20, 24L QFN.EPS
______________________________________________________________________________________
11
MAX8890
Package Information
Integrated Cellular RF-Section
Power-Management IC
MAX8890
Package Information (continued)
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.
12 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2001 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.