MAX8890EGCAGF [MAXIM]
Analog Circuit;
| 型号： | MAX8890EGCAGF |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Analog Circuit |
| 文件： | 总12页 (文件大小：419K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-2075; Rev 0; 7/01
Integrated Cellular RF-Section
Power-Management IC
General Description
Features
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.
ꢀ Three 100mA Low-Dropout Linear Regulators
ꢀ Low 50mV Dropout Voltage at 100mA
1ꢀ ꢁutput Voltage Aꢂꢂuraꢂc ꢁOer Temperature
ꢀ
ꢀ Preset 1.8V to 3.3V ꢁutput Voltages
(in 50mV Inꢂrements)
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.
ꢀ Low 45µV
ꢁutput Voltage Noise
RMS
ꢀ Low 180µA ꢁperating Supplc Current
ꢀ 2.5V to 5.5V Input Voltage Range
ꢀ 67dB PSRR
Each LDO has its own individual enable (ON/OFF) con-
trol to maximize design flexibility. The reference is pow-
ered 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 sup-
plying 100mA with a low 50mV dropout and is opti-
mized for low noise and high crosstalk-isolation.
Designed with internal P-channel MOSFET pass transis-
tors, the MAX8890’s low 180µA operating supply cur-
rent is independent of load.
ꢀ 10µVp-p Channel-to-Channel Crosstalk
ꢀ Short-Cirꢂuit Proteꢂtion
ꢀ Thermal ꢁOerload Proteꢂtion
ꢀ 0.01µA Shutdown Current
ꢀ Tinc 12-Pin 4mm x 4mm QFN Paꢂkage
Ordering Information
PART
TEMP. RANGE
PIN-PACKAGE
Other features include short-circuit and thermal over-
load protection. The MAX8890 is available in a com-
MAX8890EGCxyz*
-40°C to +85°C
12 (4 x 4) QFN
✕
pact, high-power, 12-pin 4mm 4mm QFN package
*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” =
with a metal pad on the underside.
Applications
Cellular Handsets
V
OUT1
, “y” = V
, and “z” = V
.
OUT2
OUT3
Single-Cell Li+ Systems
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.
3-Cell NiMH, NiCD, or Alkaline Systems
Personal Digital Assistants (PDAs)
Standard Preset Output
Voltage Suffixes
Typical Operating Circuit
ꢁUTPUT
VꢁLTAGE (V)
ꢁUTPUT
VꢁLTAGE (V)
INPUT
SUFFIX
SUFFIX
OUTPUT #1
IN1
OUT1
A
B
D
F
3.30
3.00
2.90
2.85
2.80
H
J
2.75
2.70
2.50
2.00
1.80
OUTPUT #2
OUTPUT #3
IN2
IN3
EN1
OUT2
OUT3
BP
K
L
MAX8890
G
M
ON
OFF
*Nonstandard output voltages between 1.80V and 3.30V are
available in 50mV increments.
EN2
EN3
GND
Standard Versions table and Pin Configuration appear at
end of data sheet.
________________________________________________________________ Maxim Integrated Products
1
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.
Integrated Cellular RF-Section
Power-Management IC
ABSꢁLUTE MAXIMUM RATINGS
IN_, EN_ to GND.......................................................-0.3V to +6V
Operating Temperature Range ...........................-40°C to +85°C
OUT_, BP to GND ......................................-0.3V to (V _ + 0.3V)
Output Short-Circuit Protection (Note A) .......................indefinite
Junction Temperature......................................................+150°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
IN
Continuous Power Dissipation (T = +70°C)
A
12-Pin 4 x 4 QFN (derate 16.9mW/°C above +70°C).......1349mW
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
(V _ = 3.6V, EN_ = IN_, C = 6.8µF, C
_ = 2.2µF, C = 0.01µF, all ceramic capacitors T = 0°C to +85°C, unless otherwise
OUT BP A
IN
IN
noted. Typical values are at T = +25°C.)
A
PARAMETER
GENERAL
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Input Voltage
V
_
2.5
5.5
V
V
IN
Input Undervoltage Lockout
Threshold
V
Rising and falling edge
2.10
2.25
45
2.45
UVLO
Input Undervoltage Hysteresis
SUPPLY CURRENT
mV
Quiescent Supply Current
Shutdown Supply Current
LINEAR REGULATORS
I
I
_ = 0
180
330
10
µA
µA
Q
OUT
EN_ = OUT_ = GND
0.01
V
_ = 0.5V + the
IN
T
T
= +85°C
-1
-2
+1
+2
A
highest of
(V , V
, or
OUT1 OUT2
Output Voltage Accuracy
V
R
_
_
%
OUT
V
I
),
OUT3
_ = 1mA to
= 0°C +85°C
OUT
A
100mA
Current Limit
I
OUT_ = GND
EN_ = GND
120
3
250
5
500
8
mA
LIM
Output Pulldown Resistance
kΩ
OUT
I
I
I
_ = 1mA
1
OUT
OUT
OUT
V
_ -
_
IN
Dropout Voltage (Note 1)
Line Regulation
_ = 50mA
_ = 100mA
25
50
mV
V
OUT
100
V
_ = (V
_+ 0.1V) to 5.5V for V
_ ≥
_ <
IN
OUT
OUT
2.4V, or V _ = 2.5V to 5.5V for V
-0.15
+0.15
%/V
IN
OUT
2.4V, I
= 1mA
OUT
10Hz to 100kHz, C
_ = 10µF ceramic,
_ = 10mA
OUT
Output Voltage Noise
45
67
64
µV
RMS
V
_ = 2.8V, I
OUT
OUT
100Hz, C
_ = 2.2µF ceramic,
OUT
Output Voltage PSRR
dB
dB
I
_ = 10mA
OUT
10kHz, C
_ = 2.2µF ceramic,
OUT
Channel-to-Channel Isolation
I
_ = 10mA
OUT
2
_______________________________________________________________________________________
Integrated Cellular RF-Section
Power-Management IC
ELECTRICAL CHARACTERISTICS (continued)
(V _ = 3.6V, EN_ = IN_, C = 6.8µF, C
_ = 2.2µF, C = 0.01µF, all ceramic capacitors T = 0°C to +85°C, unless otherwise
OUT BP A
IN
IN
noted. Typical values are at T = +25°C.)
A
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
ENABLE LOGIC CONTROL
EN_ Input Threshold
V
_
2.5V ≤ V _ ≤ 5.5V
0.4
-1
1.6
+1
V
EN
IN
EN_ Input Bias Current
I
_
V
_ = 5.5V or 0, T = +85°C
EN
µA
EN
A
THERMAL PROTECTION
Thermal Shutdown Temperature
Thermal Shutdown Hysteresis
T
Rising temperature
160
15
°C
°C
SHDN
∆T
SHDN
ELECTRICAL CHARACTERISTICS
(V _ = 3.6V, EN_ = IN_, C = 6.8µF, C
_ = 2.2µF, C = 0.01µF, all ceramic capacitors T = -40°C to +85°C, unless otherwise
OUT BP A
IN
IN
noted.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
MAX
UNITS
GENERAL
Input Voltage
V
_
2.5
5.5
V
V
IN
Input Undervoltage Lockout
Threshold
V
Rising and Falling edge
2.10
2.45
UVLO
SUPPLY CURRENT
Quiescent Supply Current
Shutdown Supply Current
LINEAR REGULATORS
I
I
_ = 0
330
10
µA
µA
Q
OUT
EN_ = OUT_ = GND
V
or V
_ = 0.5V + the highest of (V
, V
,
IN
OUT1 OUT2
Output Voltage Accuracy
V
R
_
_
-2
+2
%
OUT
), I
_ = 1mA to 100mA
OUT3 OUT
Current Limit
I
OUT_ = GND
EN_ = GND
110
3
500
8
mA
LIM
Output Pulldown Resistance
kΩ
OUT
V
_ -
_
IN
Dropout Voltage (Note 1)
Line Regulation
I
_ = 100mA
100
mV
OUT
V
OUT
V
_ = (V
_+ 0.1V) to 5.5V for V
_ ≥
_ <
IN
OUT
OUT
2.4V, or V _ = 2.5V to 5.5V for V
-0.15
+0.15
%/V
IN
OUT
2.4V, I
= 1mA
OUT
ENABLE LOGIC CONTROL
EN_ Input Threshold
V
_
2.5V ≤ V _ ≤ 5.5V
0.4
-1
1.6
1
V
EN
IN
EN_ Input Bias Current
I
_
V
_ = 5.5V or 0, T = +85°C
EN
µA
EN
A
Note 1: The Dropout Voltage is defined as V _ - V
_, when V
_ is 100mV below the set output voltage (the value of V
_ for
OUT
IN
OUT
OUT
V _ = V
IN
_ + 500mV). Since the minimum input voltage range is 2.5V, this specification is only meaningful when the set
OUT
output voltage exceeds 2.7V (V
≥ 2.7V).
OUT_(NOM)
Note 2: Specifications to -40°C are guaranteed by design, not production tested.
_______________________________________________________________________________________
3
Integrated Cellular RF-Section
Power-Management IC
Typical Operating Characteristics
(Circuit of Figure 1, MAX8890EGCGGG, V = 3.3V, EN_ = IN_, T = +25°C, unless otherwise noted.)
IN
A
OUTPUT VOLTAGE
vs. INPUT VOLTAGE
OUTPUT VOLTAGE
vs. LOAD CURRENT
OUTPUT VOLTAGE
vs. TEMPERATURE
3.0
2.5
2.0
1.5
1.0
0.5
0
2.83
2.82
2.81
2.80
2.79
2.78
2.77
2.83
2.82
2.81
2.80
2.79
2.78
2.77
I
= 100mA
60
I
= NO LOAD
OUT
OUT
0
1
2
3
4
5
6
0
20
40
60
80
100
-40
-15
10
35
85
INPUT VOLTAGE (V)
LOAD CURRENT (mA)
TEMPERATURE (°C)
DROPOUT VOLTAGE
vs. LOAD CURRENT
GROUND-PIN CURRENT
vs. INPUT VOLTAGE
GROUND-PIN CURRENT
vs. LOAD CURRENT
200
180
160
140
120
100
80
100
95
90
85
80
75
70
65
60
55
50
70
60
50
40
30
20
10
0
ONLY ONE OUTPUT ENABLED
(EN1 = IN, EN2 = EN3 = GND)
T
A
= +25°C
I
= 100mA
OUT1
T
A
= +85°C
60
T
A
= -40°C
I
= NO LOAD
OUT
40
ONLY ONE OUTPUT ENABLED
(EN1 = IN, EN2 = EN3 = GND)
20
0
0
20
40
60
80
100
0
1
2
3
4
5
6
0
20
40
60
80
100
LOAD CURRENT (mA)
INPUT VOLTAGE (V)
LOAD CURRENT (mA)
GROUND-PIN CURRENT
vs. TEMPERATURE
POWER-SUPPLY REJECTION RATIO
CHANNEL-TO-CHANNEL ISOLATION
80
70
60
50
40
30
20
10
0
80
70
60
50
40
30
20
10
0
120
110
100
90
80
70
LOW-IMPEDANCE INPUT
I
= 100mA
OUT1
C
OUT
= 1µF + 0.1µF
60
IN
I
I
= 100mA SINUSOIDAL LOAD
= 10mA
ONLY ONE OUTPUT ENABLED
(EN1 = IN, EN2 = EN3 = GND)
OUT1
OUT3
I
= 10mA
50
1000
-40
-15
10
35
60
85
0.01
0.1
1
10
100
0.1
1
10
100
1000
TEMPERATURE (°C)
FREQUENCY (kHz)
FREQUENCY (kHz)
4
_______________________________________________________________________________________
Integrated Cellular RF-Section
Power-Management IC
Typical Operating Characteristics (continued)
(Circuit of Figure 1, MAX8890EGCGGG, V = 3.3V, EN_ = IN_, T = +25°C, unless otherwise noted.)
IN
A
LINE TRANSIENT RESPONSE
LOAD TRANSIENT
LOAD TRANSIENT NEAR DROPOUT
MAX8890 toc12
MAX8890 toc10
MAX8890 toc11
4.0V
3.5V
A
A
B
A
B
B
2.8V
40µs/div
20µs/div
20µs/div
A. V = 3.5V to 4.0V, 200mV/div
IN
A. I _ = 1mA to 100mA, 50mA/div
OUT
A. I _ = 1mA to 100mA, 50mA/div
OUT
OUT
V = 2.9V (V _ + 100mV)
IN OUT
B. V
= 2.8V, 2mV/div
B. V _ = 2.8V, 20mV/div
B. V _ = 2.8V, 20mV/div
OUT_
OUT
I
= 100mA
V
IN
= 3.3V (V _ +500mV)
OUT
OUT
STARTUP WAVEFORM
STARTUP WAVEFORM
(C = 0.01µF)
BP
(C = 0.1µF)
BP
CROSSTALK VOLTAGE
MAX8890 toc14
MAX8890 toc15
1000
LOW-IMPEDANCE INPUT
I
I
= 100mA SINUSOIDAL LOAD
= 10mA
OUT1
OUT3
A
B
A
B
100
10
C
C
1
1000
0.1
1
10
100
20µs/div
5ms/div
FREQUENCY (kHz)
A. V = 0 to 3.3V, 5V/div
A. V = 0 to 3.3V, 5V/div
IN
IN
B. V
= 2.8V, 2V/div
B. V _ = 2.8V, 2V/div
OUT_
OUT
C. V = 1.25V, 1V/div
C. V = 1.25V, 1V/div
BP
BP
OUT
R
_ = 28Ω (100mA)
R
_ = 28Ω (100mA)
OUT
_______________________________________________________________________________________
5
Integrated Cellular RF-Section
Power-Management IC
Typical Operating Characteristics (continued)
(Circuit of Figure 1, MAX8890EGCGGG, V = 3.3V, EN_ = IN_, T = +25°C, unless otherwise noted.)
IN
A
ENABLE WAVEFORM
(1ST OUTPUT)
ENABLE WAVEFORM
(2ND OUTPUT)
MAX8890 toc16
MAX8890 toc17
A
A
B
B
C
D
C
D
20µs/div
20µs/div
A. V = 0 to 3.3V, 5V/div
A. V = 0 to 3.3V, 5V/div
EN1
B. V
EN2
B. V
= 2.8V, R
= 28Ω (100mA), 2V/div
= 2.8V, R
= 28Ω (100mA), 2V/div
OUT1
OUT1
OUT2
OUT2
C. V = 1.25V, 1V/div
C. V = 1.25V, 1V/div
BP
BP
D. I , 200mA/div
IN
D. I , 200mA/div
IN
V
IN
= 3.3V, EN2 = EN3 = GND, C = 0.01µF
V
IN
= 3.3V, EN1 = IN, EN3 = GND, C = 0.01µF
BP
BP
Pin Description
PIN
NAME
FUNCTION
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).
1
IN1
Regulator 2 Input. Supply voltage can range from 2.5V to V . Bypass with a capacitor to GND (see
IN1
Capacitor Selection and Regulator Stability).
2
3
4
IN2
OUT2
EN1
Regulator 2 Output. Sources up to 100mA. Bypass with a 2.2µF ceramic capacitor to GND.
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.
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.
5
6
EN2
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.
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.
7
8
9
BP
GND
IN3
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 V . Bypass with a capacitor to GND (see
IN1
Capacitor Selection and Regulator Stability).
10
11
12
OUT3
GND
Regulator 3 Output. Sources up to 100mA. Bypass with a 2.2µF ceramic capacitor to GND.
Ground. Connect both ground pins together externally, as close to the IC as possible.
Regulator 1 Output. Sources up to 100mA. Bypass with a 2.2µF ceramic capacitor to GND.
OUT1
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.
EXPOSED
PAD
GND
6
_______________________________________________________________________________________
Integrated Cellular RF-Section
Power-Management IC
INPUT
2.5V TO 5.5V
OUTPUT #1
(1.8V TO 3.3V)*
IN1
OUT1
C
OUT1
C
IN
2.2µF
4.7µF
OUTPUT #2
IN2
IN3
EN1
OUT2
OUT3
BP
(1.8V TO 3.3V)*
C
2.2µF
OUT2
OUTPUT #3
(1.8V TO 3.3V)*
OUT3
2.2µF
MAX8890
C
ON
OFF
C
BP
EN2
EN3
0.01µF
GND
*SEE THE Ordering Information AND
Preset Output Voltage Suffixes SECTIONS
Figure 1. Typical Application Circuit
battery, each LDO is designed with 45µV
from 10Hz to 100kHz and PSRR of 67dB.
noise
RMS
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 low-
dropout 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 per-
fect for single-cell Li+ battery or 3-cell NiMH battery
applications.
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 MOS-
FET 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 base-
drive currents under large loads. The MAX8890 does
not suffer from these problems and consumes only
180µA of quiescent current (all 3 regulators enabled).
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 con-
nected 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 volt-
age is too high, the pass-transistor gate is pulled up,
allowing less current to flow to the output.
Current Limit (Short-Circuit Protection)
The MAX8890 contains separate current-limit circuitry
for each linear regulator. The device monitors and con-
trols the gate voltage of each pass transistor, limiting
the regulator’s output current to 250mA (typ). The out-
put can be shorted to ground for an indefinite period of
time without damage to the part as long as the maxi-
mum continuous power dissipation rating is not
exceeded.
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 character-
istics. Designed for single-cell Li+ battery applications
where a pulsed current demand is required from the
Output Voltage Selection
The MAX8890 is supplied with factory-set output volt-
ages from 1.8V to 3.3V in 50mV increments. The three-
letter part number suffix identifies the output voltage for
each regulator. For example, the MAX8890EGCAKM’s
output voltages are preset to 3.3V (V
), 2.5V
OUT1
(V
), and 1.8V (V
).
OUT3
OUT2
_______________________________________________________________________________________
7
Integrated Cellular RF-Section
Power-Management IC
LINEAR REGULATOR #1
R
SENSE
IN1
OUT1
THERMAL
SHDN
ERROR
AMPLIFIER
CURRENT
LIMIT
CONTROL
LOCIC
IN1
BP
REF
1.25V
STARTUP
CIRCUITRY
EN1
IN2
GND
LINEAR REGULATOR #2
LINEAR REGULATOR #3
OUT2
OUT3
EN2
IN3
EN3
Figure 2. Functional Diagram
5kΩ resistor. The capacitance and load determine the
rate at which V _ 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.
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 cur-
rent to 0.01µA.
OUT
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.
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
_______________________________________________________________________________________
Integrated Cellular RF-Section
Power-Management IC
When the junction temperature exceeds T = 160°C, a
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.
J
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 maxi-
mum junction-temperature rating of T = 150°C.
J
Applications Information
The MAX8890 load-transient response graphs (see
Typical Operating Characteristics) show two compo-
nents 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.
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.
Input-Output (Dropout) Voltage
A regulator’s minimum input-to-output voltage differen-
tial (dropout voltage) determines the lowest useable
input supply voltage. Once the linear regulator reaches
dropout, the series pass transistor is fully on and regu-
lation ceases. The output voltage tracks the input volt-
age 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-to-
The input capacitor (C _) lowers the source imped-
IN
ance 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.
source on-resistance (R
) multiplied by the load
DS(ON)
current (see Typical Operating Characteristics):
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 tem-
perature operation.
V
= V _ - V
_ = R
DS(ON)
✕ I _
OUT
DROPOUT
IN
OUT
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 per-
formance improvement and are therefore not recom-
mended. Do not place any additional loading on this
reference bypass pin.
_______________________________________________________________________________________
9
Integrated Cellular RF-Section
Power-Management IC
Pin Configuration
Standard Versions
VERSION
TOP MARK
AAAA
TOP VIEW
OUT1 GND OUT3
MAX8890EGCAAA
MAX8890EGCDDD
MAX8890EGCGGG
MAX8890EGCMMM
MAX8890EGCAKM
11
AAAC
12
10
AAAE
IN1
1
9
IN3
AAAJ
AAAK
IN2
2
3
8
7
GND
BP
MAX8890
OUT2
Chip Information
TRANSISTOR COUNT: 1472
4
5
EN2
✕
6
PROCESS: BiCMOS
EN1
EN3
4
4 QFN
10 ______________________________________________________________________________________
Integrated Cellular RF-Section
Power-Management IC
Package Information
______________________________________________________________________________________ 11
Integrated Cellular RF-Section
Power-Management IC
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.
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