Rainbow Electronics MAX8621Z User Manual

General Description

The MAX8621Y/MAX8621Z power-management inte­grated 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 dri­ver, 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, allow­ing 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 back­lighting or provide an open-drain connection for resis­tors such as in feedback networks.

Applications

Cellular Handsets

Smart Phones, PDAs

Digital Cameras

MP3 Players

Wireless LAN

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

Dual Step-Down DC-DC Power-Management ICs

for Portable Devices

________________________________________________________________ Maxim Integrated Products 1

Ordering Information

MAX8621Y
MAX8621Z

IN1

IN2

IN3

PWRON

EN3

EN4

SEL2

ENDR

REFBP

GND

OUT1

OUT2

OUT3

OUT4

DR

LX1

FB1

PGND1

LX2

FB2

PGND2

RESET

SEL1

EN2

INPUT

2.6V TO 5.5V

INPUT

OUT4
3V, 150mA

OUT3

1.8V, 150mA

OUT2

2.6V, 300mA

OUT1

2.6V, 300mA

BUCK1

1.375V, 500mA

BUCK2

1.8V, 500mA

RESET

Typical Operating Circuit

19-3539; Rev 0; 1/05

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.

Pin Configuration appears at end of data sheet.

EVALUATION KIT AVAILABLE

PART TEMP RANGE PIN-PACKAGE

MAX8621YETG -40°C to +85°C

MAX8621ZETG -40°C to +85°C

24 Thin QFN
4mm x 4mm (T2444-4)

24 Thin QFN
4mm x 4mm (T2444-4)

MAX8621Y/MAX8621Z

Dual Step-Down DC-DC Power-Management ICs
for Portable Devices

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VIN= 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, TA= -40°C to

+85°C, unless otherwise noted. Typical values are at T

A

= +25°C.) (Notes 1, 2)

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.

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.

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 (TA= +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

PARAMETER CONDITIONS

MIN

TYP

MAX

UNIT

Input Supply Range After startup 2.6 5.5 V

Shutdown Supply Current V

IN

= 4.2V (Note 3) 2 15 µA

VIN = 3.7V; BUCK1, BUCK2, OUT1, OUT2 on; other
circuits off

300

No-Load Supply Current

VIN = 3.7V, BUCK1 and BUCK2 on, all LDOs on

µA

Light-Load Supply Current

V

IN

= 3.7V, BUCK1 and BUCK2 with 500µA load each,

OUT1 and OUT2 on, other circuits off

µA

UNDERVOLTAGE LOCKOUT

VIN rising

Undervoltage Lockout (Note 4)

V

IN

falling

V

THERMAL SHUTDOWN

Threshold TA rising

°C

Hysteresis 15 °C

REFERENCE

Reference Bypass Output
Voltage

T

A

= 0°C to +85°C

V

REF Supply Rejection 2.6V ≤ VIN ≤ 5.5V 0.2

mV/V

LOGIC AND CONTROL INPUTS

Input Low Level PWRON, EN2, EN3, EN4; 2.6V ≤ VIN ≤ 5.5V 0.4 V

PWRON, EN2, EN3, EN4; 2.6V ≤ VIN ≤ 4.2V

Input High Level

PWRON, EN2, EN3, EN4; 2.6V ≤ V

IN

≤ 5.5V

V

Logic Input Current EN3, EN4; 0V < VIN < 5.5V -1 +1 µA

Tristate Low Input Threshold SEL_ 0.3 0.7 1.0 V

Tristate Low Input Threshold
Hysteresis

SEL_ 50 mV

Tristate High Input Threshold SEL_

V

IN

-

VIN -

VIN -

V

160

2.35 2.55

+160

1.25

0.8V

275

710

2.70 2.85 3.05

1.235 1.250 1.265

1.44 1.12

1.2V

0.4V

MAX8621Y/MAX8621Z

Dual Step-Down DC-DC Power-Management ICs

for Portable Devices

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(VIN= 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, TA= -40°C to

+85°C, unless otherwise noted. Typical values are at T

A

= +25°C.) (Notes 1, 2)

PARAMETER CONDITIONS

UNIT

Tristate High Input Threshold
Hysteresis

SEL_ 50 mV

PWRON, EN2 Pulldown Resistor
to GND

kΩ

STEP-DOWN DC-DC CONVERTER 1 (BUCK1)

Supply Current I

LOAD

= 0A, no switching 40 µA

Output Voltage Range 0.6 3.3 V

FB1 Threshold Voltage V

FB1

falling

V

FB1 Threshold Line Regulation 2.6V ≤ VIN ≤ 5.5V 0.3 %/V

FB1 Threshold Voltage Hysteresis
(% of V

FB1

)

1%

Shutdown

FB1 Bias Current

V

FB1

= 0.5V

µA

p-MOSFET switch (I

LIMP

)

Current Limit

n-MOSFET rectifier (I

LIMN

)

mA

p-MOSFET switch, I

LX1

= -40mA

1.5

On-Resistance

n-MOSFET rectifier, I

LX1

= 40mA

0.8

Ω

Rectifier Off-Current Threshold I

LXOFF

45 70 mA

t

ON

Minimum On- and Off-Times

t

OFF

95

ns

STEP-DOWN DC-DC CONVERTER 2 (BUCK2)

Supply Current I

LOAD

= 0A, no switching 40 µA

Output Voltage Range 0.6 3.3 V

FB2 Threshold Voltage V

FB2

falling

V

FB2 Threshold Line Regulation 2.6V ≤ VIN ≤ 5.5V 0.3 %/V

FB2 Threshold Voltage Accuracy
(Falling) (% of VFB2)

I

LOAD

= 0A

%

FB2 Threshold Voltage Hysteresis
(% of VFB2)

1%

Shutdown

FB2 Bias Current

V

FB

= 0.5V

µA

p-MOSFET switch

Current Limit

n-MOSFET rectifier

mA

p-MOSFET switch, I

LX2

= -40mA

1.5

On-Resistance

n-MOSFET rectifier, I

LX2

= 40mA

0.8

Ω

Rectifier Off-Current Threshold I

LXOFF

45 70 mA

t

ON

Minimum On- and Off-Times

t

OFF

95

ns

MIN TYP MAX

400 800 1600

670 1000 1500

750 1000 1330

-2.5 +2.5

670 1000 1500

750 1000 1330

0.603

0.01

0.01

0.65

0.35

107

0.603

0.01

0.01

0.65

0.35

107

MAX8621Y/MAX8621Z

Dual Step-Down DC-DC Power-Management ICs
for Portable Devices

4 _______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS (continued)

(VIN= 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, TA= -40°C to

+85°C, unless otherwise noted. Typical values are at T

A

= +25°C.) (Notes 1, 2)

PARAMETER CONDITIONS

UNIT

OUT1 (LDO1)

TA = 0°C to +85°C

I

LOAD

= 1mA, 3.7V ≤ VIN ≤ 5.5V,

relative to V

OUT(NOM)

Output Voltage Accuracy

I

LOAD

= 150mA, relative to V

OUT(NOM)

0

%

Output Current 300 mA

Current Limit V

OUT1

= 0V

940 mA

Dropout Voltage I

LOAD

= 200mA, TA = +85°C

420 mV

Load Regulation

V

IN

= greater of 3.7V or (V

OUT(NOM)

+ 0.7V),

1mA < I

LOAD

< 300mA, V

SEL1

= V

SEL2

= 0V

1.2 %

Power-Supply Rejection
∆V

OUT1

/∆V

IN2

10Hz to 10kHz, C

OUT1

= 4.7µF, I

LOAD

= 30mA 60 dB

Output Noise Voltage (RMS) 100Hz to 100kHz, C

OUT1

= 4.7µF, I

LOAD

= 30mA 45

µV

RMS

0 < I

LOAD

< 300mA 4.7

Output Capacitor for Stable
Operation

0 < I

LOAD

< 150mA 2.2

µF

Ground Current I

LOAD

= 500µA 21 µA

OUT2 (LDO2)

TA = 0°C to +85°C

I

LOAD

= 1mA, 3.7V ≤ V

IN_

≤ 5.5V,

relative to V

OUT(NOM)

Output Voltage Accuracy

I

LOAD

= 150mA, relative to V

OUT(NOM)

0

%

Output Current 300 mA

Current Limit V

OUT2

= 0V

940 mA

Dropout Voltage I

LOAD

= 200mA , T

A

= +85°C

420 mV

Load Regulation 1mA < I

LOAD

< 300mA, V

SEL1

= V

SEL2

= 0V 1.2 %

Power-Supply Rejection
∆V

OUT2

/∆V

IN2

10Hz to 10kHz, C

OUT2

= 4.7µF, I

LOAD

= 30mA 60 dB

Output Noise Voltage (RMS) 100Hz to 100kHz, C

OUT2

= 4.7µF, I

LOAD

= 30mA 45

µV

RMS

0 < I

LOAD

< 300mA 4.7

Output Capacitor for Stable
Operation

0 < I

LOAD

< 150mA 2.2

µF

Ground Current I

LOAD

= 500µA 21 µA

OUT3 (LDO3)

TA = 0°C to +85°C

I

LOAD

= 1mA, 3.7V ≤ V

IN_

≤ 5.5V,

relative to V

OUT(NOM)

Output Voltage Accuracy

I

LOAD

= 75mA, relative to V

OUT(NOM)

0

%

Output Current 150 mA

Current Limit V

OUT3

= 0V

650 mA

Dropout Voltage I

LOAD

= 100mA , TA = +85°C

210 mV

Load Regulation 1mA < I

LOAD

< 150mA, V

SEL1

= V

SEL2

= 0V 0.6 %

MIN TYP MAX

-1.3 +0.6 +2.0

TA = -40°C to +85°C -2.3 +2.5

310 550

TA = -40°C to +85°C -2.3 +2.5

TA = -40°C to +85°C -2.3 +2.5

-1.3 +0.6 +2.0

310 550

-1.3 +0.3 +2.0

165 360

200

200

100

MAX8621Y/MAX8621Z

Dual Step-Down DC-DC Power-Management ICs

for Portable Devices

_______________________________________________________________________________________ 5

ELECTRICAL CHARACTERISTICS (continued)

(VIN= 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, TA= -40°C to

+85°C, unless otherwise noted. Typical values are at T

A

= +25°C.) (Notes 1, 2)

PARAMETER CONDITIONS

UNIT

Power-Supply Rejection
∆V

OUT3

/∆V

IN2

10Hz to 10kHz, C

OUT3

= 2.2µF, I

LOAD

= 30mA 60 dB

Output Noise Voltage (RMS) 100Hz to 100kHz, C

OUT3

= 2.2µF, I

LOAD

= 30mA 45

µV

RMS

Output Capacitor for Stable
Operation

0 < I

LOAD

< 150mA 2.2 µF

OUT4 (LDO4)

)

TA = 0°C to
+85°C

)

I

LOAD

= 1mA, 3.7V ≤

V

IN_

≤ 5.5V, relative to

V

OUT(NOM)

TA = -40°C to +85°C

Output Voltage Accuracy

I

LOAD

= 75mA, relative to V

OUT(NOM)

0

%

Output Current 150 mA

Current Limit V

OUT4

= 0V

650 mA

Dropout Voltage I

LOAD

= 100mA, T

A

= +85°C

210 mV

Load Regulation 1mA < I

LOAD

< 150mA, V

SEL1

= V

SEL2

= 0 0.6 %

Power-Supply Rejection
∆V

OUT4

/∆V

IN2

10Hz to 10kHz, C

OUT4

= 2.2µF, I

LOAD

= 30mA 60 dB

Output Noise Voltage (RMS) 100Hz to 100kHz, C

OUT4

= 2.2µF, I

LOAD

= 30mA 45

µV

RMS

Output Capacitor for Stable
Operation

0 < I

LOAD

< 150mA 2.2 µF

DRIVER (DR)

ENDR Turn-On Threshold IDR = 1mA

V

ENDR Input Current V

ENDR

= 0V and 5.5V -1 +1 µA

DR Output Low Voltage IDR = 150mA, V

ENDR

= 3.7V 0.2 0.4 V

DR Off-Current (Leakage) VDR = VIN = 5.5V, V

ENDR

= 0V -1 +1 µA

RESET

Output High Voltage

V

OUT1

V

Output Low Voltage I

SINK

= 1mA 0.3 V

RESET Threshold Percentage of nominal OUT1 rising when RESET falls 84 87 90 %
RESET Active Timeout Period From OUT1 ≥ 87% until RESET = HIGH 60 ms

Pullup Resistance to OUT1 81420kΩ

Note 1: V

IN1

, V

IN2

, and V

IN3

are shorted together and single input is referred to as VIN.

Note 2: All units are 100% production tested at T

A

= +85°C. Limits over the operating range are guaranteed by design.

Note 3: OUT1, OUT2, OUT3, OUT4, LX1, and LX2 to ground.
Note 4: When the input voltage is greater than 2.85V (typ), the UVLO comparator trips and the threshold is reduced to 2.35V (typ).

This allows the system to start normally until the input voltage decays to 2.35V.

MIN TYP MAX

V

OUT(NOM

V

OUT(NOM

≥ 1.8V -1.3 +0.3 +2.0

= 1.5V -1.30 +0.3 +2.35

-2.3 +2.5

165 360

100

0.65

- 0.3V

MAX8621Y/MAX8621Z

Dual Step-Down DC-DC Power-Management ICs
for Portable Devices

6 _______________________________________________________________________________________

Typical Operating Characteristics

(Circuit of Figure 3, V

IN1

= V

IN2

= V

IN3

= 3.6V, PWRON = IN, V

BUCK1

= 1.375V, V

BUCK2

= 1.8V, V

OUT1

= 2.6V, V

OUT2

= 2.6V, V

OUT3

= 1.8V, V

OUT4

= 3.0V, SEL1 = SEL2 = open, LX1 = LX2 = Murata LQH32CN2R2M53, TA= +25°C, unless otherwise noted.)

SUPPLY CURRENT

vs. INPUT VOLTAGE

MAX8621 toc01

INPUT VOLTAGE (V)

SUPPLY CURRENT (µA)

5.04.54.03.53.0

120

140

160

180

200

220

240

260

280

300

100

2.5 5.5

NO LOAD
BUCK1, BUCK2, OUT1, OUT2: ON

STARTUP WAVEFORMS

MAX8621 toc02

50µs/div

5V/div
0

PWRON

BUCK1

BUCK2

OUT1

OUT2

2V/div
0
2V/div
0

5V/div
0

5V/div
0

SHUTDOWN WAVEFORMS

MAX8621 toc03

100µs/div

5V/div
0

PWRON

BUCK1

BUCK2

OUT1

OUT2

2V/div
0

2V/div
0

5V/div
0

5V/div
0

10mA LOAD ON ALL FOUR OUTPUTS

RESET WAVEFORMS

MAX8621 toc04

20ms/div

2V/div
0

PWRON

OUT1

RESET

2V/div

0

2V/div
0

LOAD = 1mA