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19-3539; Rev 1; 8/05
IT
TION K
VALUA
E
BLE
AVAILA
Dual Step-Down DC-DC Power-Management ICs
for Portable Devices
General Description
The MAX8621Y/MAX8621Z power-management inte-
grated circuits (PMICs) are designed for a variety of
portable devices including cellular handsets. These
PMICs include two high-efficiency step-down DC-DC
converters, four low-dropout linear regulators (LDOs)
with pin-programmable capability, one open-drain dri-
ver, a 60ms (typ) reset timer, and power-on/off control
logic. These devices offer high efficiency with a no-load
supply current of 160µA, and their small thin QFN 4mm
x 4mm package makes them ideal for portable devices.
The step-down DC-DC converters utilize a proprietary
4MHz hysteretic-PWM control scheme that allows for
ultra-small external components. Internal synchronous
rectification improves efficiency and eliminates the
external Schottky diode that is required in conventional
step-down converters. The output voltage is adjustable
from 0.6V to 3.3V. The output current is guaranteed up
to 500mA.
The four LDOs offer low 45µV
RMS
output noise and low
dropout of only 100mV at 100mA. OUT1 and OUT2
deliver 300mA (min) of continuous output current.
OUT3 and OUT4 deliver 150mA (min) of continuous
output current. The output voltages are pin selectable
by SEL1 and SEL2 for flexibility. The MAX8621Y/
MAX8621Z offer different sets of LDO output voltages.
A microprocessor reset output (RESET) monitors OUT1
and warns the system of impending power loss, allow-
ing safe shutdown.
RESET
asserts during power-up,
power-down, shutdown, and fault conditions where
V
OUT1
is below its regulation voltage.
A 200mA driver output is provided to control LED back-
lighting or provide an open-drain connection for resis-
tors such as in feedback networks.
Features
♦
Two 500mA Step-Down Converters
Up to 4MHz Switching Frequency
Adjustable Output from 0.6V to 3.3V
♦
Four Low-Noise LDOs with Pin-Programmable
Output Voltages
♦
One Open-Drain Driver
♦
60ms (typ) Reset Timer
♦
Power-On/Off Control Logic and Sequencing
♦
4mm x 4mm x 0.8mm 24-Pin Thin QFN
MAX8621Y/MAX8621Z
Ordering Information
PART
MAX8621YETG
MAX8621YETG+
MAX8621ZETG
MAX8621ZETG+
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
24 Thin QFN
4mm x 4mm (T2444-4)
24 Thin QFN
4mm x 4mm (T2444-4)
24 Thin QFN
4mm x 4mm (T2444-4)
24 Thin QFN
4mm x 4mm (T2444-4)
+ Denotes lead-free package.
Typical Operating Circuit
INPUT
2.6V TO 5.5V
IN1
LX1
BUCK1
1.375V, 500mA
MAX8621Y
MAX8621Z
IN2
FB1
Applications
Cellular Handsets
Smart Phones, PDAs
Digital Cameras
MP3 Players
Wireless LAN
Pin Configuration appears at end of data sheet.
IN3
PGND1
LX2
BUCK2
1.8V, 500mA
PWRON
FB2
SEL1
SEL2
PGND2
OUT1
OUT1
2.6V, 300mA
RESET
OUT2
2.6V, 300mA
OUT3
1.8V, 150mA
OUT4
3V, 150mA
INPUT
GND
DR
EN2
EN3
RESET
OUT2
EN4
OUT3
ENDR
REFBP
OUT4
________________________________________________________________
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.
Dual Step-Down DC-DC Power-Management ICs
for Portable Devices
MAX8621Y/MAX8621Z
ABSOLUTE MAXIMUM RATINGS
PWRON, IN1, IN2, IN3,
RESET,
FB1, FB2,
ENDR, REFBP, SEL1, SEL2 to GND..................-0.3V to +6.0V
EN2,
EN3, EN4, DR to GND.......................-0.3V to (V
IN3
+ 0.3V)
OUT1, OUT2, OUT3, OUT4 to GND...........-0.3V to (V
IN2
+ 0.3V)
PGND1, PGND2 to GND ......................................-0.3V to + 0.3V
LX1, LX2 Current..........................................................±1.5A
RMS
LX1, LX2 to GND (Note 1) ..........................-0.3V to (V
IN1
+ 0.3V)
DR Current......................................................................0.5A
RMS
Continuous Power Dissipation (T
A
= +70°C)
24-Pin 4mm x 4mm Thin QFN
(derate 27.8mW/°C above +70°C) ..........................2222.2mW
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 1:
LX_ has internal clamp diodes to GND and IN1. Applications that forward-bias these diodes should take care not to exceed
the IC’s package dissipation limits.
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
IN
= 3.7V, C
IN1
= 10µF, C
IN2
= C
IN3
= 4.7µF, C
OUT1
= C
OUT2
= 4.7µF, C
OUT3
= C
OUT4
= 2.2µF, C
REFBP
= 0.01µF, T
A
= -40°C to
+85°C, unless otherwise noted. Typical values are at T
A
= +25°C.) (Notes 1, 2)
PARAMETER
Input Supply Range
Shutdown Supply Current
No-Load Supply Current
After startup
V
IN
= 4.2V (Note 3)
V
IN
= 3.7V; BUCK1, BUCK2, OUT1, OUT2 on; other
circuits off
VIN = 3.7V, BUCK1 and BUCK2 on, all LDOs on
Light-Load Supply Current
UNDERVOLTAGE LOCKOUT
Undervoltage Lockout (Note 4)
THERMAL SHUTDOWN
Threshold
Hysteresis
REFERENCE
Reference Bypass Output
Voltage
REF Supply Rejection
LOGIC AND CONTROL INPUTS
Input Low Level
Input High Level
Logic Input Current
Tristate Low Input Threshold
Tristate Low Input Threshold
Hysteresis
Tristate High Input Threshold
PWRON,
EN2,
EN3, EN4; 2.6V
≤
V
IN
≤
5.5V
PWRON,
EN2,
EN3, EN4; 2.6V
≤
V
IN
≤
4.2V
PWRON,
EN2,
EN3, EN4; 2.6V
≤
V
IN
≤
5.5V
EN3, EN4; 0V < V
IN
< 5.5V
SEL_
SEL_
SEL_
V
IN
-
1.2V
-1
0.3
0.7
50
V
IN
-
0.8V
V
IN
-
0.4V
1.44
1.12
1.25
+1
1.0
0.4
V
V
µA
V
mV
V
T
A
= 0°C to +85°C
2.6V
≤
V
IN
≤
5.5V
1.235
1.250
0.2
1.265
V
mV/V
T
A
rising
+160
15
°C
°C
V
IN
rising
V
IN
falling
2.70
2.85
2.35
3.05
2.55
V
V
IN
= 3.7V, BUCK1 and BUCK2 with 500µA load each,
OUT1 and OUT2 on, other circuits off
CONDITIONS
MIN
2.6
2
160
275
710
µA
TYP
MAX
5.5
15
300
UNIT
V
µA
µA
2
_______________________________________________________________________________________
Dual Step-Down DC-DC Power-Management ICs
for Portable Devices
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= 3.7V, C
IN1
= 10µF, C
IN2
= C
IN3
= 4.7µF, C
OUT1
= C
OUT2
= 4.7µF, C
OUT3
= C
OUT4
= 2.2µF, C
REFBP
= 0.01µF, T
A
= -40°C to
+85°C, unless otherwise noted. Typical values are at T
A
= +25°C.) (Notes 1, 2)
PARAMETER
Tristate High Input Threshold
Hysteresis
PWRON,
EN2
Pulldown Resistor
to GND
STEP-DOWN DC-DC CONVERTER 1 (BUCK1)
Supply Current
Output Voltage Range
FB1 Threshold Voltage
FB1 Threshold Line Regulation
FB1 Threshold Voltage Hysteresis
(% of V
FB1
)
FB1 Bias Current
Current Limit
On-Resistance
Rectifier Off-Current Threshold
Minimum On- and Off-Times
Shutdown
V
FB1
= 0.5V
p-MOSFET switch (I
LIMP
)
n-MOSFET rectifier (I
LIMN
)
p-MOSFET switch, I
LX1
= -40mA
n-MOSFET rectifier, I
LX1
= 40mA
I
LXOFF
t
ON
t
OFF
I
LOAD
= 0A, no switching
0.6
V
FB2
falling
2.6V
≤
V
IN
≤
5.5V
I
LOAD
= 0A
-2.5
1
Shutdown
V
FB
= 0.5V
p-MOSFET switch
n-MOSFET rectifier
p-MOSFET switch, I
LX2
= -40mA
n-MOSFET rectifier, I
LX2
= 40mA
I
LXOFF
t
ON
t
OFF
670
750
0.01
0.01
1000
1000
0.65
0.35
45
107
95
1500
1330
1.5
0.8
70
0.603
0.3
+2.5
670
750
V
FB1
falling
2.6V
≤
V
IN
≤
5.5V
I
LOAD
= 0A, no switching
0.6
0.603
0.3
1
0.01
0.01
1000
1000
0.65
0.35
45
107
95
40
3.3
1500
1330
1.5
0.8
70
40
3.3
µA
V
V
%/V
%
µA
mA
Ω
mA
ns
SEL_
400
CONDITIONS
MIN
TYP
50
800
1600
MAX
UNIT
mV
kΩ
MAX8621Y/MAX8621Z
STEP-DOWN DC-DC CONVERTER 2 (BUCK2)
Supply Current
Output Voltage Range
FB2 Threshold Voltage
FB2 Threshold Line Regulation
FB2 Threshold Voltage Accuracy
(Falling) (% of VFB2)
FB2 Threshold Voltage Hysteresis
(% of VFB2)
FB2 Bias Current
Current Limit
On-Resistance
Rectifier Off-Current Threshold
Minimum On- and Off-Times
µA
V
V
%/V
%
%
µA
mA
Ω
mA
ns
_______________________________________________________________________________________
3
Dual Step-Down DC-DC Power-Management ICs
for Portable Devices
MAX8621Y/MAX8621Z
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= 3.7V, C
IN1
= 10µF, C
IN2
= C
IN3
= 4.7µF, C
OUT1
= C
OUT2
= 4.7µF, C
OUT3
= C
OUT4
= 2.2µF, C
REFBP
= 0.01µF, T
A
= -40°C to
+85°C, unless otherwise noted. Typical values are at T
A
= +25°C.) (Notes 1, 2)
PARAMETER
OUT1 (LDO1)
Output Voltage Accuracy
Output Current
Current Limit
Dropout Voltage
Load Regulation
Power-Supply Rejection
ΔV
OUT1
/ΔV
IN2
Output Noise Voltage (RMS)
Output Capacitor for Stable
Operation
Ground Current
OUT2 (LDO2)
Output Voltage Accuracy
Output Current
Current Limit
Dropout Voltage
Load Regulation
Power-Supply Rejection
ΔV
OUT2
/ΔV
IN2
Output Noise Voltage (RMS)
Output Capacitor for Stable
Operation
Ground Current
OUT3 (LDO3)
Output Voltage Accuracy
Output Current
Current Limit
Dropout Voltage
Load Regulation
V
OUT3
= 0V
I
LOAD
= 100mA , T
A
= +85°C
1mA < I
LOAD
< 150mA, V
SEL1
= V
SEL2
= 0V
165
360
100
0.6
I
LOAD
= 1mA, 3.7V
≤
V
IN_
≤
5.5V,
relative to V
OUT(NOM)
T
A
= 0°C to +85°C
T
A
= -40°C to +85°C
-1.3
-2.3
0
150
650
210
mA
mA
mV
%
+0.3
+2.0
+2.5
%
V
OUT2
= 0V
I
LOAD
= 200mA , T
A
= +85°C
1mA < I
LOAD
< 300mA, V
SEL1
= V
SEL2
= 0V
10Hz to 10kHz, C
OUT2
= 4.7µF, I
LOAD
= 30mA
100Hz to 100kHz, C
OUT2
= 4.7µF, I
LOAD
= 30mA
0 < I
LOAD
< 300mA
0 < I
LOAD
< 150mA
I
LOAD
= 500µA
310
550
200
1.2
60
45
4.7
2.2
21
I
LOAD
= 1mA, 3.7V
≤
V
IN_
≤
5.5V,
relative to V
OUT(NOM)
T
A
= 0°C to +85°C
T
A
= -40°C to +85°C
-1.3
-2.3
0
300
940
420
mA
mA
mV
%
dB
µV
RMS
µF
µA
+0.6
+2.0
+2.5
%
V
OUT1
= 0V
I
LOAD
= 200mA, T
A
= +85°C
V
IN
= greater of 3.7V or (V
OUT(NOM)
+ 0.7V),
1mA < I
LOAD
< 300mA, V
SEL1
= V
SEL2
= 0V
10Hz to 10kHz, C
OUT1
= 4.7µF, I
LOAD
= 30mA
100Hz to 100kHz, C
OUT1
= 4.7µF, I
LOAD
= 30mA
0 < I
LOAD
< 300mA
0 < I
LOAD
< 150mA
I
LOAD
= 500µA
310
550
200
1.2
60
45
4.7
2.2
21
I
LOAD
= 1mA, 3.7V
≤
V
IN
≤
5.5V,
relative to V
OUT(NOM)
T
A
= 0°C to +85°C
T
A
= -40°C to +85°C
-1.3
-2.3
0
300
940
420
mA
mA
mV
%
dB
µV
RMS
µF
µA
+0.6
+2.0
+2.5
%
CONDITIONS
MIN
TYP
MAX
UNIT
I
LOAD
= 150mA, relative to V
OUT(NOM)
I
LOAD
= 150mA, relative to V
OUT(NOM)
I
LOAD
= 75mA, relative to V
OUT(NOM)
4
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