ACTIVE-SEMI ACT8712 Four channel integrated power management ic for handheld portable equipment Datasheet

ACT8712
Rev0, 25-Feb-08
Advanced Product Information―All Information Subject to Change
Four Channel Integrated Power Management IC
for Handheld Portable Equipment
FEATURES
GENERAL DESCRIPTION
• Multiple Patents Pending
• Li+ Battery Charger with Integrated MOSFET
The patent-pending ACT8712 is a complete, cost
effective, highly efficient ActivePMUTM power management solution that is ideal for a wide range of
portable handheld equipment. This device integrates two PWM step-down DC/DC converters, one
PWM step-up DC/DC converter with over-voltage
protection (OVP) and a full-featured linear-mode
Li+ battery charger into a single, thin, space-saving
package. An I2C Serial Interface provides programmability for the DC/DC converters and battery
charger.
− Programmable Charge Current up to 1A
− ON/OFF Control and Status Indication
• Three Integrated Regulators
− 550mA Step-Down DC/DC
− 750mA Step-Down DC/DC
− Step-Up DC/DC with OVP for WLED Bias
• I2CTM Compatible Serial Interface
− Programmable Output Voltages
− Configurable Operating Modes
REG1 and REG2 are fixed-frequency, current-mode
PWM step-down DC/DC converters that are optimized for high efficiency and are capable of supplying up to 550mA and 750mA, respectively. REG3 is
a fixed-frequency PWM step-up converter that
safely and efficiently biases a string of up to seven
white-LEDs for backlighting. The battery charger
incorporates an internal power MOSFET for constant-current/constant-voltage, thermally regulated
charging of a single-cell Li+ battery. All DC/DC converters’ output voltage are programmable and controllable via the I2C interface.
• Minimal External Components
• 4x4mm, Thin-QFN (TQFN44-24) Package
− Only 0.75mm Height
− RoHS Compliant
APPLICATIONS
• Portable Devices and PDAs
• Digital Media Players
The ACT8712 is available in a tiny 4mm x 4mm
24-pin Thin-QFN package that is just 0.75mm thin.
• Battery Operated Devices
• GPS Receivers, etc.
SYSTEM BLOCK DIAGRAM
VIN
CHGLEV
nSTAT
nMSTR
nIRQ
nRSTO
SCL
SDA
ON1
ON2
Battery
Programmable
Up to 1A
Single-Cell Li+
Battery Charger
REG1
Step-Down
DC/DC
System Control
REG2
Step-Down
DC/DC
REG3
ACT8712
PMU
Active
Innovative Products. Active Solutions.
ActivePMUTM is a trademark of Active-Semi.
I2CTM is a trademark of Philips Electronics.
OUT1
1.1V to 4.4V
Up to 550mA
Step-Up
DC/DC
TM
-1-
OUT2
1.1V to 4.4V
Up to 750mA
Pb-free
OUT3
WLED Bias
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Copyright © 2008 Active-Semi, Inc.
ACT8712
Rev0, 25-Feb-08
TABLE OF CONTENTS
GENERAL INFORMATION ...................................................................................... P. 01
Functional Block Diagram .................................................................................................. p. 03
Ordering Information .......................................................................................................... p. 04
Pin Configuration ............................................................................................................... p. 04
Pin Descriptions ................................................................................................................. p. 05
Absolute Maximum Ratings ............................................................................................... p. 07
SYSTEM MANAGEMENT ....................................................................................... P. 08
Register Descriptions ......................................................................................................... p. 08
Electrical Characteristics .................................................................................................... p. 09
I2C Interface Electrical Characteristics ............................................................................... p. 10
Typical Performance Characteristics ................................................................................. p. 11
Functional Description ....................................................................................................... p. 12
STEP-DOWN DC/DC CONVERTERS ...................................................................... P. 14
Electrical Characteristics ................................................................................................... p. 14
Register Descriptions ......................................................................................................... p. 15
Typical Performance Characteristics ................................................................................. p. 20
Functional Description ....................................................................................................... p. 21
WLED BIAS DC/DC CONVERTER ......................................................................... P. 23
Electrical Characteristics .................................................................................................... p. 23
Register Descriptions ......................................................................................................... p. 24
Typical Performance Characteristics ................................................................................. p. 26
Functional Description ....................................................................................................... p. 27
SINGLE-CELL Li+ BATTERY CHARGER ............................................................... P. 29
Electrical Characteristics .................................................................................................... p. 29
Register Descriptions ......................................................................................................... p. 30
Typical Performance Characteristics ................................................................................. p. 32
Functional Description ....................................................................................................... p. 33
PACKAGE INFORMATION ...................................................................................... P. 36
Innovative Products. Active Solutions.
ActivePMUTM is a trademark of Active-Semi.
I2CTM is a trademark of Philips Electronics.
-2-
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Copyright © 2008 Active-Semi, Inc.
ACT8712
Rev0, 25-Feb-08
FUNCTIONAL BLOCK DIAGRAM
VSYS
BODY AND
VSYS
CONTROL
AC Adaptor
or USB
ACT8712
VIN
4.3V to 6V
BAT
Li+ Battery
+
CURRENT
SENSE
VINUVLO
nSTAT
4.0V
VOLTAGE
SENSE
CHARGE STATUS
OUT2
Charge
Control
CHGLEV
FLOAT
PRECONDITION
2.9V
THERMAL
REGULATION
110°C
VP1
To Battery
SCL
Serial
Interface
SDA
REG1
OUT2
nRSTO
SW1
OUT1
OUT1
GP12
VP2
To Battery
VSYS
REG2
nMSTR
PUSH
BUTTON
OUT2
SW2
OUT2
OUT2
GP12
nIRQ
System
Control
SW3
ON1
OVP3
REG3
ON2
GA
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ActivePMUTM is a trademark of Active-Semi.
I2CTM is a trademark of Philips Electronics.
To Battery
OUT3
-3-
FB3
GP3
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Copyright © 2008 Active-Semi, Inc.
ACT8712
Rev0, 25-Feb-08
ORDERING INFORMATIONcd
PART
NUMBER
VOUT1
VOUT2
PACKAGE
PINS
TEMPERATURE
RANGE
ACT8712QLCHA-T
1.2V
3.3V
TQFN44-24
24
-40°C to +85°C
ACT8712QLEHA-T
1.8V
3.3V
TQFN44-24
24
-40°C to +85°C
OUTPUT VOLTAGE CODES
C
D
E
F
G
H
1.2V
1.5V
1.8V
2.5V
3.0V
3.3V
c: Output voltage options detailed in this table represent standard voltage options, and are available for samples or production orders.
Additional output voltage options, as detailed in the Output Voltage Codes table, are available for production subject to minimum order
quantities. Contact Active-Semi for more information regarding semi-custom output voltage combinations.
d: All Active-Semi components are RoHS Compliant and with Pb-free plating unless specified differently. The term Pb-free means
semiconductor products that are in compliance with current RoHS (Restriction of Hazardous Substances) standards.
PIN CONFIGURATION
TOP VIEW
BAT
CHGLEV
nSTAT
SW3
GP3
OVP3
24
23
22
21
20
19
VIN
1
18 FB3
SCL
2
17 GA
SDA
3
16 VSYS
nIRQ
4
nMSTR
5
nRSTO
6
15 ON1
ACT8712
14 ON2
EP
10
11
12
GP12
SW2
VP2
9
SW1
OUT1
8
VP1
7
13 OUT2
Thin - QFN (TQFN44-24)
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ActivePMUTM is a trademark of Active-Semi.
I2CTM is a trademark of Philips Electronics.
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Copyright © 2008 Active-Semi, Inc.
ACT8712
Rev0, 25-Feb-08
PIN DESCRIPTIONS
PIN
NAME
DESCRIPTION
1
VIN
Power Input for the Battery Charger. Bypass VIN to GA with a capacitor placed as close to
the IC as possible. The battery charger and both step-down DC/DCs (REG1 and REG2)
are automatically enabled when a valid voltage is present on VIN.
2
SCL
Clock Input for I2C Serial Interface. Data is read on the rising edge of the clock.
3
SDA
Data Input for I2C Serial Interface. Data is read on the rising edge of the clock.
4
nIRQ
Open-Drain Push-Button Status Output. nIRQ is an open-drain output which sinks current
when nMSTR is asserted.
5
nMSTR
Master Enable Input. Drive nMSTR to GA or to a logic low to enable IC.
6
nRSTO
Open-Drain Reset Output. nRSTO asserts low for the reset timeout period of 300ms whenever the IC is enabled.
7
OUT1
Output Feedback Sense for REG1. Connect this pin directly to the output node to connect
the internal feedback network to the output voltage.
8
VP1
Power Input for REG1. Bypass to GP12 with a high quality ceramic capacitor placed as
close as possible to the IC.
9
SW1
Switching Node Output for REG1. Connect this pin to the switching end of the inductor.
10
GP12
Power Ground for REG1 and REG2. Connect GA, GP12, and GP3 together at a single
point as close to the IC as possible.
11
SW2
Switching Node Output for REG2. Connect this pin to the switching end of the inductor.
12
VP2
Power Input for REG2. Bypass to GP12 with a high quality ceramic capacitor placed as
close as possible to the IC.
13
OUT2
Output Feedback Sense for REG2. Connect this pin directly to the output node to connect
the internal feedback network to the output voltage.
14
ON2
Enable Control Input for REG3. ON2 is functional only when ON1 is driven high, nMSTR is
driven low, or when a valid supply voltage is present on VIN. Drive ON2 to VSYS or to a
logic high for normal operation, drive to GA or a logic low to disable REG3.
15
ON1
Enable Control Input for REG1 and REG2. Drive ON1 to VSYS or to a logic high for normal
operation, drive to GA or to a logic low to disable REG1 and REG2.
16
VSYS
Power Bypass for System Management Circuitry. Bypass to GA with a high quality ceramic
capacitor placed as close as possible to the IC. VSYS is internally connected to the higher
voltage of either VVIN or VBAT. Do not load VSYS with more than 100µA.
Innovative Products. Active Solutions.
ActivePMUTM is a trademark of Active-Semi.
I2CTM is a trademark of Philips Electronics.
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Copyright © 2008 Active-Semi, Inc.
ACT8712
Rev0, 25-Feb-08
PIN DESCRIPTIONS CONT’D
PIN
NAME
DESCRIPTION
17
GA
Analog Ground. Connect GA directly to a quiet ground node. Connect GA, GP12, and GP3
together at a single point as close to the IC as possible.
18
FB3
Feedback Sense for REG3. Connect this pin to the LED string current sense resistor to
sense the LED current.
19
OVP3
Over-Voltage Protection Input for REG3. Connect this pin directly to the output node to
sense and prevent over-voltage conditions.
20
GP3
Power Ground for REG3. Connect GP3 directly to a power ground plane. Connect GA,
GP12, and GP3 together at a single point as close to the IC as possible.
21
SW3
Switching Node Output for REG3. Connect this pin to the switching end of the inductor.
22
nSTAT
Active-Low Open-Drain Charger Status Output. nSTAT sinks current whenever the charger
is charging the battery, and is high-Z otherwise. nSTAT has a 6mA (typ) current limit, allowing it to directly drive an indicator LED without additional external components. To generate
a logic-level output, connect nSTAT to an appropriate supply voltage (typically OUT2)
through a 10kΩ or greater pull-up resistor.
23
CHGLEV
Tri-State Charging State Select Input. When ISET1[ ] = [0000], drive CHGLEV to VSYS or
to a logic high for high-current charging mode (maximum charge current of 500mA), and
drive to GA or a logic low for low-current charging mode (maximum charge current of
100mA). Allow CHGLEV to float (|ICHGLEV| < 2µA) to disable the charger.
24
BAT
Battery Charger Output. Connect this pin directly to the battery anode (+ terminal) to sense
the battery voltage.
EP
EP
Exposed Pad. Must be soldered to ground on PCB.
Innovative Products. Active Solutions.
ActivePMUTM is a trademark of Active-Semi.
I2CTM is a trademark of Philips Electronics.
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Copyright © 2008 Active-Semi, Inc.
ACT8712
Rev0, 25-Feb-08
ABSOLUTE MAXIMUM RATINGSc
PARAMETER
VALUE
UNIT
VP1, SW1, VP2, SW2 to GP12,
VSYS, OUT1, OUT2, FB3, BAT, CHGLEV, nSTAT, ON1, ON2, nRSTO, nMSTR, nIRQ,
SCL, SDA to GA
-0.3 to +6
V
OVP3, SW3 to GP3
-0.3 to +30
V
SW1 to VP1, SW2 to VP2
-6 to +0.3
V
VIN to GA
t <1ms and duty cycle <1%
Steady State
-0.3 to +7
-0.3 to +6
V
V
-0.3 to +0.3
V
1.8
W
-40 to 85
°C
Junction Temperature
125
°C
Storage Temperature
-55 to 150
°C
300
°C
GP12, GP3 to GA
RMS Power Dissipation (TA = 70°C)
Operating Temperature Range
Lead Temperature (Soldering, 10 sec)
c: Do not exceed these limits to prevent damage to the device. Exposure to absolute maximum rating conditions for long periods may
affect device reliability.
Innovative Products. Active Solutions.
ActivePMUTM is a trademark of Active-Semi.
I2CTM is a trademark of Philips Electronics.
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Copyright © 2008 Active-Semi, Inc.
ACT8712
Rev0, 25-Feb-08
SYSTEM MANAGEMENT
REGISTER DESCRIPTIONS
Table 1:
Global Register Map
OUTPUT
ADDRESS
DATA (DEFAULT VALUE)
HEX
A7
A6
A5
A4
A3
A2
A1
A0
D7
D6
D5 D4 D3 D2
D1
D0
CHGR
08h
0
0
0
0
1
0
0
0
0
0
0
0
R
R
R
R
CHGR
09h
0
0
0
0
1
0
0
1
0
1
R
R
R
R
R
R
CHGR
0Ah
0
0
0
0
1
0
1
0
0
0
0
0
R
R
R
R
CHGR
0Bh
0
0
0
0
1
0
1
1
R
R
R
R
0
0
R
0
REG1
10h
0
0
0
1
0
0
0
0
R
V
V
V
V
V
V
V
REG1
11h
0
0
0
1
0
0
0
1
R
R
R
R
R
R
R
0
REG1
12h
0
0
0
1
0
0
1
0
0
0
R
R
R
R
R
R
REG1
13h
0
0
0
1
0
0
1
1
R
R
R
0
R
0
R
1
REG2
20h
0
0
1
0
0
0
0
0
R
V
V
V
V
V
V
V
REG2
21h
0
0
1
0
0
0
0
1
R
R
R
R
R
R
R
0
REG2
22h
0
0
1
0
0
0
1
0
0
1
R
R
R
R
R
R
REG2
23h
0
0
1
0
0
0
1
1
R
R
R
0
R
0
R
1
REG3
30h
0
0
1
1
0
0
0
0
R
R
1
1
1
1
1
1
REG3
31h
0
0
1
1
0
0
0
1
R
R
R
R
R
R
R
0
REG3
32h
0
0
1
1
0
0
1
0
0
0
0
0
0
0
0
0
REG3
33h
0
0
1
1
0
0
1
1
0
0
0
R
R
0
R
0
KEY:
R: Read-Only bit. No Default Assigned.
V: Default Values Depend on Voltage Option. Default Values May Vary.
Note: Addresses other than those specified in Table 1 may be used for factory settings. Do not access any registers other than those
specified in Table 1.
Innovative Products. Active Solutions.
ActivePMUTM is a trademark of Active-Semi.
I2CTM is a trademark of Philips Electronics.
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Copyright © 2008 Active-Semi, Inc.
ACT8712
Rev0, 25-Feb-08
SYSTEM MANAGEMENT
ELECTRICAL CHARACTERISTICS
(VVSYS = 3.6V, TA = 25°C, unless otherwise specified.)
PARAMETER
TEST CONDITIONS
VSYS Operating Voltage Range
MIN
2.6
VSYS UVLO Threshold
VSYS Voltage Rising
VSYS UVLO Hysteresis
VSYS Voltage Falling
2.25
VSYS Output Resistance
Oscillator Frequency
VSYS Supply Current
TYP
1.35
ON1 = ON2 = GA, CHGLEV = floating
nMSTR Internal Pull-Up Resistance
250
2.4
MAX
UNIT
5.5
V
2.55
V
80
mV
10
Ω
1.6
1.85
MHz
1.5
µA
500
kΩ
Logic High Input Voltage
ON1, ON2, nMSTR
Logic Low Input Voltage
ON1, ON2, nMSTR
0.4
V
Logic Low Output Voltage
nIRQ, nRSTO, ISINK = 5mA
0.3
V
Leakage Current
nIRQ, nRSTO, VnIRQ = VnRSTO = 4.2V
1
µA
360
ms
nRSTO Delay
1.4
240
V
300
Thermal Shutdown Temperature
Temperature Rising
160
°C
Thermal Shutdown Hysteresis
Temperature Falling
20
°C
Innovative Products. Active Solutions.
ActivePMUTM is a trademark of Active-Semi.
I2CTM is a trademark of Philips Electronics.
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Copyright © 2008 Active-Semi, Inc.
ACT8712
Rev0, 25-Feb-08
SYSTEM MANAGEMENT
I2C INTERFACE ELECTRICAL CHARACTERISTICS
(VVSYS = 3.6V, TA = 25°C, unless otherwise specified.)
PARAMETER
TEST CONDITIONS
MIN
SCL, SDA Low Input Voltage
SCL, SDA High Input Voltage
TYP
MAX
UNIT
0.4
V
1.4
SCL, SDA Leakage Current
SDA Low Output Voltage
IOL = 5mA
SCL Clock Period, tSCL
fSCL clock freq = 400kHz
V
1
µA
0.3
V
2.5
µs
SDA Data In Setup Time to SCL High, tSU
100
ns
SDA Data Out Hold Time after SCL Low, tHD
300
ns
Start Condition
100
ns
SDA Data High Hold Time after Clock High, tSP Stop Condition
100
ns
SDA Data Low Setup Time to SCL Low, tST
Figure 1:
I2C Serial Bus Timing
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ActivePMUTM is a trademark of Active-Semi.
I2CTM is a trademark of Philips Electronics.
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Copyright © 2008 Active-Semi, Inc.
ACT8712
Rev0, 25-Feb-08
SYSTEM MANAGEMENT
TYPICAL PERFORMANCE CHARACTERISTICS
(VVSYS = 3.6V, TA = 25°C, unless otherwise specified.)
Oscillator Frequency vs. Temperature
ON1 = ON2 = GA
Supply Current (µA)
1.65
ACT8712-002
1.68
Frequency (MHz)
VSYS Current vs. Temperature
3
ACT8712-001
1.71
1.62
1.59
1.56
VVSYS = 4.2V
2
VVSYS = 3.6V
VVSYS = 3.2V
1
1.53
1.50
-40
-20
0
20
40
60
0
-40
85
Temperature (°C)
20
40
60
85
Shutdown Sequence
ACT8712-004
ACT8712-003
CH2
0
Temperature (°C)
Startup Sequence
CH1
-20
CH1
CH2
CH3
CH3
CH4
CH4
CH1: VnMSTR, 5V/div
CH2: VnRSTO, 2V/div
CH3: VON1, 5V/div
CH4: VOUT1, 2V/div
CH1: VnMSTR, 5V/div
CH2: VnRSTO, 2V/div
CH3: VON1, 5V/div
CH4: VOUT1, 2V/div
TIME: 100ms/div
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ActivePMUTM is a trademark of Active-Semi.
I2CTM is a trademark of Philips Electronics.
- 11 -
TIME: 100ms/div
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Copyright © 2008 Active-Semi, Inc.
ACT8712
Rev0, 25-Feb-08
SYSTEM MANAGEMENT
FUNCTIONAL DESCRIPTION
General Description
The ACT8712 offers an array of system management functions that allow it to provide optimal performance in a wide range of applications.
I2C Serial Interface
At the core of the ACT8712’s flexible architecture is
an I2C interface that permits optional programming
capability to enhance overall system performance.
To ensure compatibility with a wide range of system
processors, the ACT8712 uses standard I2C commands; I2C write-byte commands are used to program the ACT8712, and I2C read-byte commands
are used to read the ACT8712’s internal registers.
The ACT8712 always operates as a slave device,
and is addressed using a 7-bit slave address followed by an eighth bit, which indicates whether the
transaction is a read-operation or a write-operation,
[1010 011x].
SDA is a bi-directional data line and SCL is a clock
input. The master initiates a transaction by issuing a
START condition, defined by SDA transitioning from
high to low while SCL is high. Data is transferred in
8-bit packets, beginning with the MSB, and is
clocked-in on the rising edge of SCL. Each packet
of data is followed by an “Acknowledge” (ACK) bit,
used to confirm that the data was transmitted successfully.
For more information regarding the I2C 2-wire serial
interface, go to the NXP website: http://www.nxp.com
Automatic Enable Due to Valid VIN Supply
The ACT8712 battery charger and step-down
DC/DC converters (REG1 and REG2) are automatically enabled when a valid input supply is applied to
VIN. Automatically enabling these functions simplifies system design and eliminates the need for external input supply-detection circuitry.
Manual Enable Due to Asserting nMSTR Low
System startup is initiated when the user presses
the push-button, asserting nMSTR low. When this
occurs, both REG1 and REG2 are enabled and
nRSTO is asserted low to hold the microprocessor
in RESET for 260ms. nRSTO goes high-Z upon
expiration of the reset timer, de-asserting the processor’s reset input and allowing the microprocessor
to initiate its power up sequence. Once the powerup routine is successfully completed, the microprocessor must assert ON1 so that the ACT8712 remains enabled after the push-button is released by
the user. Upon completion of the start-up sequence
the processor assumes control of the power system
and all further operation is software-controlled.
Manual Enable Due to Asserting ON1 High
The ACT8712 is compatible with applications that
do not utilize it’s push-button control function, and
may be enabled by simply driving ON1 to a logichigh. In this case, the signal driving ON1 controls
enable/disable timing, although software-controlled
enable/disable sequences are still supported if the
processor assumes control of the power system
once the startup sequence is completed.
System Startup and Shutdown
The ACT8712 features a flexible control architecture that supports a variety of software-controlled
enable/disable functions that make it a simple yet
flexible and highly configurable solution.
The ACT8712 is automatically enabled when any of
the following conditions exists:
1) A valid supply voltage is present at VIN,
2) nMSTR is asserted low, or
3) ON1 is asserted high.
If any of these conditions is true, the ACT8712 enables REG1 and REG2, powering up the system
processor so that the startup and shutdown sequences may be controlled via software. Each of
these startup conditions are described in detail below.
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Shutdown Sequence
Once a successful power-up routine is completed,
the system processor controls the operation of the
power system, including the system shutdown timing and sequence. The ACT8712 asserts nIRQ low
when nMSTR is asserted low, providing a simple
means of alerting the system processor when the
user wishes to shut the system down. Asserting
nIRQ interrupts the system processor, initiating an
interrupt service routine in the processor which will
reveal that the user pressed the push-button. The
microprocessor may validate the input, such as by
ensuring that the push-button is asserted for a minimum amount of time, then initiates a softwarecontrolled power-down routine, the final step of
which is to de-assert the ON1 input, disabling
REG1 and REG2 and shutting the system down.
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ACT8712
Rev0, 25-Feb-08
SYSTEM MANAGEMENT
nMSTR Enable Input
In most applications, connect nMSTR to an active
low, momentary push-button switch to utilize the
ACT8712’s closed-loop enable/disable functionality.
If a momentary-on switch is not used, drive nMSTR
to GA or to a logic low to initiate a startup sequence.
Enable/Disable Inputs (ON1 and ON2)
The ACT8712 provides two manual enable/disable
inputs, ON1 and ON2. ON1 is the master enable
input. When driven high, ON1 enables REG1 and
REG2. ON2 is the enable input for REG3. ON2 is
used to enable REG3 when any of the following
conditions exists:
1) A valid supply voltage is present at VIN,
2) nMSTR is asserted low, or
3) ON1 is asserted high.
Power-On Reset Output
The ACT8712 integrates a 260ms power-on reset
generator, reducing system size and cost. nRSTO
is an open-drain output. Connect a 10kΩ or greater
pull-up resistor from nRSTO to an appropriate voltage supply, typically OUT2. nRSTO asserts low
upon startup and remains low until the reset-timeout
period expires, at which point nRSTO goes high-Z.
nIRQ Output
The ACT8712 provides an active-low, open-drain
push-button status output that sinks current when
nMSTR is driven to a logic-low. Connect a pull-up
resistor from nIRQ to an appropriate voltage supply.
nIRQ is typically used to drive the interrupt input of
the system processor, and is useful in a variety of
software-controlled enable/disable control routines.
Thermal Shutdown
The ACT8712 integrates thermal shutdown protection circuitry to prevent damage resulting from excessive thermal stress, as may be encountered under fault conditions. This circuitry disables all regulators if the ACT8712 die temperature exceeds
160°C, and prevents the regulators from being enabled until the IC temperature drops by 20°C (typ).
Innovative Products. Active Solutions.
ActivePMUTM is a trademark of Active-Semi.
I2CTM is a trademark of Philips Electronics.
- 13 -
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Copyright © 2008 Active-Semi, Inc.
ACT8712
Rev0, 25-Feb-08
STEP-DOWN DC/DC CONVERTERS
ELECTRICAL CHARACTERISTICS
(VVP1 = 3.6V, TA = 25°C, unless otherwise specified.)
PARAMETER
TEST CONDITIONS
VP1 Operating Voltage Range
MIN
3.1
VP1 UVLO Threshold
Input Voltage Rising
VP1 UVLO Hysteresis
Input Voltage Falling
2.9
Output Voltage Regulation Accuracy
ON1 = GA, VVP1 = 4.2V
0.1
c
VNOM1 < 1.3V, IOUT1 = 10mA
-2.4%
VNOM1
VNOM1 ≥ 1.3V, IOUT1 = 10mA
-1.2%
VNOM1
VVP1 = Max(VNOM1 + 1V, 3.2V) to 5.5V
Load Regulation
IOUT1 = 10mA to 550mA
Current Limit
VOUT1 ≥ 20% of VNOM1
UNIT
5.5
V
3.1
V
mV
130
Line Regulation
Oscillator Frequency
3
MAX
80
Standby Supply Current
Shutdown Supply Current
TYP
200
µA
1
µA
+1.8%
+1.8%
V
0.15
%/V
0.0017
%/mA
0.65
0.85
A
1.35
1.6
1.85
MHz
VOUT1 = 0V
530
kHz
PMOS On-Resistance
ISW1 = -100mA
0.35
0.60
Ω
NMOS On-Resistance
ISW1 = 100mA
0.23
0.40
Ω
SW1 Leakage Current
VVP1 = 5.5V, VSW1 = 5.5V or 0V
1
µA
Power Good Threshold
94
%VNOM1
Minimum On-Time
70
ns
c: VNOM1 refers to the nominal output voltage level for VOUT1 as defined by the Ordering Information section.
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- 14 -
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Copyright © 2008 Active-Semi, Inc.
ACT8712
Rev0, 25-Feb-08
STEP-DOWN DC/DC CONVERTERS
REGISTER DESCRIPTIONS
Note: See Table 1 for default register settings.
Table 2:
REG1 Control Register Map
ADDRESS
DATA
D7
D6
D5
D4
10h
R
VRANGE
11h
R
R
R
R
12h
W/E
W/E
R
13h
R
R
R
D3
D2
D1
D0
R
R
R
MODE
R
R
R
R
R
W/E
R
W/E
OK
W/E
VSET
R: Read-Only bits. Default Values May Vary.
W/E: Write-Exact bits. Read/Write bits which must be written exactly as specified in Table 1.
Table 3:
REG1 Control Register Bit Descriptions
ADDRESS
NAME
BIT
ACCESS
FUNCTION
DESCRIPTION
10h
VSET
[5:0]
R/W
REG1 Output Voltage Selection
See Table 4
10h
VRANGE
[6]
R/W
REG1 Reference Voltage
Selection
[7]
R
[0]
R/W
11h
[7:1]
R
READ ONLY
12h
[5:0]
R
READ ONLY
12h
[7:6]
W/E
WRITE-EXACT
13h
[0]
W/E
WRITE-EXACT
[1]
R
13h
[2]
W/E
WRITE-EXACT
13h
[3]
R
READ ONLY
13h
[4]
W/E
WRITE-EXACT
13h
[7:5]
R
READ ONLY
10h
11h
13h
MODE
OK
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0
Min VOUT = 1.1V
1
Min VOUT = 1.25V
READ ONLY
Mode Selection
REG1 Power-OK
- 15 -
0
PFM/PWM
1
Forced PWM
0
Output is not OK
1
Output is OK
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ACT8712
Rev0, 25-Feb-08
STEP-DOWN DC/DC CONVERTERS
REGISTER DESCRIPTIONS CONT’D
Table 4:
REG1/VSET[ ] Output Voltage Setting
REG1/VSET[5:4]
REG1/VSET
[3:0]
REG1/VRANGE = [0]
REG1/VRANGE = [1]
00
01
10
11
00
01
10
11
0000
N/A
N/A
1.455
1.860
1.250
2.050
2.850
3.650
0001
N/A
N/A
1.480
1.890
1.300
2.100
2.900
3.700
0010
N/A
1.100
1.505
1.915
1.350
2.150
2.950
3.750
0011
N/A
1.125
1.530
1.940
1.400
2.200
3.000
3.800
0100
N/A
1.150
1.555
1.965
1.450
2.250
3.050
3.850
0101
N/A
1.175
1.585
1.990
1.500
2.300
3.100
3.900
0110
N/A
1.200
1.610
2.015
1.550
2.350
3.150
3.950
0111
N/A
1.225
1.635
2.040
1.600
2.400
3.200
4.000
1000
N/A
1.255
1.660
2.065
1.650
2.450
3.250
4.050
1001
N/A
1.280
1.685
2.090
1.700
2.500
3.300
4.100
1010
N/A
1.305
1.710
2.115
1.750
2.550
3.350
4.150
1011
N/A
1.330
1.735
2.140
1.800
2.600
3.400
4.200
1100
N/A
1.355
1.760
2.165
1.850
2.650
3.450
4.250
1101
N/A
1.380
1.785
2.190
1.900
2.700
3.500
4.300
1110
N/A
1.405
1.810
2.200
1.950
2.750
3.550
4.350
1111
N/A
1.430
1.835
2.245
2.000
2.800
3.600
4.400
(N/A): Not Available
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- 16 -
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Copyright © 2008 Active-Semi, Inc.
ACT8712
Rev0, 25-Feb-08
STEP-DOWN DC/DC CONVERTERS
ELECTRICAL CHARACTERISTICS
(VVP2 = 3.6V, TA = 25°C, unless otherwise specified.)
PARAMETER
TEST CONDITIONS
VP2 Operating Voltage Range
MIN
3.1
VP2 UVLO Threshold
Input Voltage Rising
VP2 UVLO Hysteresis
Input Voltage Falling
2.9
Output Voltage Regulation Accuracy
ON1 = GA, VVP2 = 4.2V
UNIT
5.5
V
3.1
V
mV
130
200
µA
0.1
1
µA
VNOM2 < 1.3V, IOUT2 = 10mA
-2.4%
VNOM2c
+1.8%
VNOM2 ≥ 1.3V, IOUT2 = 10mA
-1.2%
VNOM2
+1.8%
Line Regulation
VVP2 = Max(VNOM2 + 1V, 3.2V) to 5.5V
Load Regulation
IOUT2 = 10mA to 750mA
Current Limit
Oscillator Frequency
3
MAX
80
Standby Supply Current
Shutdown Supply Current
TYP
VOUT2 ≥ 20% of VNOM2
V
0.15
%/V
0.0017
%/mA
0.85
1.1
A
1.35
1.6
1.85
MHz
VOUT2 = 0V
530
kHz
PMOS On-Resistance
ISW2 = -100mA
0.28
0.50
Ω
NMOS On-Resistance
ISW2 = 100mA
0.20
0.35
Ω
SW2 Leakage Current
VVP2 = 5.5V, VSW2 = 5.5V or 0V
1
µA
Power Good Threshold
94
%VNOM2
Minimum On-Time
70
ns
c: VNOM2 refers to the nominal output voltage level for VOUT2 as defined by the Ordering Information section.
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- 17 -
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Copyright © 2008 Active-Semi, Inc.
ACT8712
Rev0, 25-Feb-08
STEP-DOWN DC/DC CONVERTERS
REGISTER DESCRIPTIONS
Note: See Table 1 for default register settings.
Table 5:
REG2 Control Register Map
ADDRESS
DATA
D7
D6
D5
D4
20h
R
VRANGE
21h
R
R
R
R
22h
W/E
W/E
R
23h
R
R
R
D3
D2
D1
D0
R
R
R
MODE
R
R
R
R
R
W/E
R
W/E
OK
W/E
VSET
R: Read-Only bits. Default Values May Vary.
W/E: Write-Exact bits. Read/Write bits which must be written exactly as specified in Table 1.
Table 6:
REG2 Control Register Bit Descriptions
ADDRESS
NAME
BIT
ACCESS
FUNCTION
DESCRIPTION
20h
VSET
[5:0]
R/W
REG2 Output Voltage Selection
See Table 7
20h
VRANGE
[6]
R/W
REG2 Reference Voltage
Selection
[7]
R
[0]
R/W
21h
[7:1]
R
READ ONLY
22h
[5:0]
R
READ ONLY
22h
[7:6]
W/E
WRITE-EXACT
23h
[0]
W/E
WRITE-EXACT
[1]
R
23h
[2]
W/E
WRITE-EXACT
23h
[3]
R
READ ONLY
23h
[4]
W/E
WRITE-EXACT
23h
[7:5]
R
READ ONLY
20h
21h
23h
MODE
OK
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0
Min VOUT = 1.1V
1
Min VOUT = 1.25V
READ ONLY
Mode Selection
REG2 Power-OK
- 18 -
0
PFM/PWM
1
Forced PWM
0
Output is not OK
1
Output is OK
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ACT8712
Rev0, 25-Feb-08
STEP-DOWN DC/DC CONVERTERS
REGISTER DESCRIPTIONS CONT’D
Table 7:
REG2/VSET[ ] Output Voltage Setting
REG2/VSET[5:4]
REG2/VSET
[3:0]
REG2/VRANGE = [0]
REG2/VRANGE = [1]
00
01
10
11
00
01
10
11
0000
N/A
N/A
1.455
1.860
1.250
2.050
2.850
3.650
0001
N/A
N/A
1.480
1.890
1.300
2.100
2.900
3.700
0010
N/A
1.100
1.505
1.915
1.350
2.150
2.950
3.750
0011
N/A
1.125
1.530
1.940
1.400
2.200
3.000
3.800
0100
N/A
1.150
1.555
1.965
1.450
2.250
3.050
3.850
0101
N/A
1.175
1.585
1.990
1.500
2.300
3.100
3.900
0110
N/A
1.200
1.610
2.015
1.550
2.350
3.150
3.950
0111
N/A
1.225
1.635
2.040
1.600
2.400
3.200
4.000
1000
N/A
1.255
1.660
2.065
1.650
2.450
3.250
4.050
1001
N/A
1.280
1.685
2.090
1.700
2.500
3.300
4.100
1010
N/A
1.305
1.710
2.115
1.750
2.550
3.350
4.150
1011
N/A
1.330
1.735
2.140
1.800
2.600
3.400
4.200
1100
N/A
1.355
1.760
2.165
1.850
2.650
3.450
4.250
1101
N/A
1.380
1.785
2.190
1.900
2.700
3.500
4.300
1110
N/A
1.405
1.810
2.200
1.950
2.750
3.550
4.350
1111
N/A
1.430
1.835
2.245
2.000
2.800
3.600
4.400
(N/A): Not Available
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I2CTM is a trademark of Philips Electronics.
- 19 -
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Copyright © 2008 Active-Semi, Inc.
ACT8712
Rev0, 25-Feb-08
STEP-DOWN DC/DC CONVERTERS
TYPICAL PERFORMANCE CHARACTERISTICS
(ACT8712QLEHA, VVP1 = VVP2 = 3.6V, L = 3.3µH, CVP1 = CVP2 = 2.2µF, COUT1 = COUT2 = 10µF, TA = 25°C, unless otherwise specified.)
REG1 Efficiency vs. Load Current
Efficiency (%)
85
4.2V
80
VOUT2 = 3.0V
90
Efficiency (%)
3.6V
90
ACT8712-006
VOUT1 = 1.8V
REG2 Efficiency vs. Load Current
100
ACT8712-005
95
75
70
65
60
4.2V
3.6V
80
70
60
55
50
50
1
10
1
1000
100
10
Output Current (mA)
OUT1 Regulation Voltage
OUT2 Voltage Accuracy (%)
OUT1 Voltage Accuracy (%)
0.222
0.0
-0.222
-0.444
IOUT2 = 35mA
0.363
0.181
0.0
-0.181
-0.363
-0.545
-20
0
20
40
60
-40
85
-20
Temperature (°C)
REG1 MOSFET Resistance
450
400
PMOS
350
RDSON (mΩ)
RDSON (mΩ)
60
85
REG2 MOSFET Resistance
NMOS
250
200
40
150
100
ACT8712-010
PMOS
350
300
20
500
ACT8712-009
550
500
450
400
0
Temperature (°C)
600
300
250
NMOS
200
150
100
50
50
0
3.0
ACT8712-008
IOUT1 = 35mA
0.444
-0.666
-40
1000
OUT2 Regulation Voltage
0.545
ACT8712-007
0.666
100
Output Current (mA)
0
3.5
4.0
4.5
5.0
5.5
3
VP1 Voltage (V)
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3.5
4.0
4.5
5.0
5.5
VP2 Voltage (V)
- 20 -
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Copyright © 2008 Active-Semi, Inc.
ACT8712
Rev0, 25-Feb-08
STEP-DOWN DC/DC CONVERTERS
FUNCTIONAL DESCRIPTION
General Description
Programming the Output Voltage
REG1 and REG2 are fixed-frequency, currentmode, synchronous PWM step down converters
that achieve peak efficiencies of up to 97%. REG1
is capable of supplying up to 550mA of output current, while REG2 supports up to 750mA. These
regulators operate with a fixed frequency of
1.6MHz, minimizing noise in sensitive applications
and allowing the use of small external components.
REG1 and REG2 are available with a variety of
standard and custom output voltages, as described
in the Ordering Information section of this datasheet. REG1 and REG2 also take advantage of the
I2C interface, and may be software-controlled in
systems that require advanced power management
functions.
By default, REG1 and REG2 each power up and
regulate to their default output voltage. Once the
system is enabled, each regulator’s output voltage
may be independently programmed to a different
value, typically in order to reduce the power consumption of a microprocessor in standby mode.
Program the output voltages via the I2C serial interface by writing to the REGx/VSETx[ ] and
REGx/VRANGE[ ] registers.
100% Duty Cycle Operation
Both REG1 and REG2 are capable of operating at
up to 100% duty cycle. During 100% duty-cycle operation, the high-side power MOSFET is held on
continuously, providing a direct connection from the
input to the output (through the inductor), ensuring
the lowest possible dropout voltage in batterypowered applications.
Synchronous Rectification
REG1 and REG2 both feature integrated n-channel
synchronous rectifiers, maximizing efficiency and
minimizing the total solution size and cost by eliminating the need for external rectifiers.
Enabling and Disabling REG1 and REG2
Enable/disable functionality is typically implemented
as part of a controlled enable/disable scheme utilizing nMSTR and other system control features of the
ACT8712. REG1 and REG2 are automatically enabled whenever any of the following conditions are
met:
1) A valid input voltage is present at VIN,
2) nMSTR is driven low, or
3) ON1 is asserted high.
When none of these conditions are true, REG1 and
REG2 are disabled, and each regulator's quiescent
supply current drops to less than 1µA.
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Programmable Operating Mode
By default, REG1 and REG2 operate in fixedfrequency PWM mode at medium to heavy loads,
then transition to a proprietary power-saving mode
at light loads in order to save power. In applications
where low noise is critical, force fixed-frequency
PWM operation across the entire load current
range, at the expense of light-load efficiency, by
setting the REGx/MODE[ ] bit to [1].
Power-OK
REG1 and REG2 each feature a variety of status
bits that can be read by the system microprocessor.
If either output voltage is lower than the power-OK
threshold, typically 6% below the programmed
regulation voltage, REGx/OK[ ] will clear to 0.
Soft-Start
REG1 and REG2 each include matched soft-start
circuitry. When enabled, the output voltages track
the internal 80µs soft-start ramp and both power up
in a monotonic manner that is independent of loading on either output. This circuitry ensures that both
outputs power up in a controlled manner, greatly
simplifying power sequencing design considerations.
Compensation
REG1 and REG2 utilize current-mode control and a
proprietary internal compensation scheme to simultaneously simplify external component selection
and optimize transient performance over their full
operating range. No compensation design is required; simply follow a few simple guidelines described below when choosing external components.
- 21 -
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Copyright © 2008 Active-Semi, Inc.
ACT8712
Rev0, 25-Feb-08
STEP-DOWN DC/DC CONVERTERS
Input Capacitor Selection
PCB Layout Considerations
The input capacitor reduces peak currents and
noise induced upon the voltage source. A 2.2µF
ceramic capacitor for each of REG1 and REG2 is
recommended for most applications.
High switching frequencies and large peak currents
make PC board layout an important part of stepdown DC/DC converter design. A good design minimizes excessive EMI on the feedback paths and
voltage gradients in the ground plane, both of which
can result in instability or regulation errors. Stepdown DC/DCs exhibit discontinuous input current,
so the input capacitors should be placed as close
as possible to the IC, and avoiding the use of vias if
possible. The inductor, input filter capacitor, and
output filter capacitor should be connected as close
together as possible, with short, direct, and wide
traces. The ground nodes for each regulator’s
power loop should be connected at a single point in
a star-ground configuration, and this point should
be connected to the backside ground plane with
multiple vias. The output node for each regulator
should be connected to its corresponding OUTx pin
through the shortest possible route, while keeping
sufficient distance from switching nodes to prevent
noise injection. Finally, the exposed pad should be
directly connected to the backside ground plane
using multiple vias to achieve low electrical and
thermal resistance.
Output Capacitor Selection
For most applications, 10µF ceramic output capacitors are recommended for both REG1 and REG2.
Although the these regulators were designed to
take advantage of the benefits of ceramic capacitors, namely small size and very-low ESR, low-ESR
tantalum capacitors can provide acceptable results
as well.
Inductor Selection
REG1 and REG2 utilize current-mode control and a
proprietary internal compensation scheme to simultaneously simplify external component selection
and optimize transient performance over their full
operating range. These devices were optimized for
operation with 3.3µH inductors, although inductors
in the 2.2µH to 4.7µH range can be used. Choose
an inductor with a low DC-resistance, and avoid
inductor saturation by choosing inductors with DC
ratings that exceed the maximum output current of
the application by at least 30%.
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- 22 -
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Copyright © 2008 Active-Semi, Inc.
ACT8712
Rev0, 25-Feb-08
WLED BIAS DC/DC CONVERTER
ELECTRICAL CHARACTERISTICS
(VVSYS = 3.6V, TA = 25°C, unless otherwise specified.)
PARAMETER
TEST CONDITIONS
c
Input Voltage Range
MIN
TYP
2
5.5
V
3.1
V
VSYS Voltage Rising
UVLO Voltage Hysteresis
VSYS Voltage Falling
80
ON2 = VIN, VFB3 = 0.3V
75
150
µA
ON2 = GA, ILOAD = 0mA
0.1
1
µA
255
275
mV
FB3 Feedback Voltage
235
FB3 Input Current
3
UNIT
UVLO Voltage Threshold
Supply Current
2.9
MAX
mV
50
Oscillator Frequency
1.35
Minimum On-Time
Maximum Duty Cycle
Switch Current Limit
Duty = 83%, L = 22µH, COUT3 = 4.7µF
Switch On-Resistance
ISW3 = 100mA
Switch Leakage Current
VSW3 = 30V, ON2 = GA
Over-Voltage Threshold
REG3/VSET[ ] = [111111]
1.6
nA
1.85
MHz
100
ns
87
92
%
500
750
mA
0.67
27.5
28.5
1.1
Ω
10
µA
29.5
V
c: As long as VSYS is within the VSYS operating range, this spec refers to the voltage range of the input that the inductor is connected
to.
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- 23 -
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Copyright © 2008 Active-Semi, Inc.
ACT8712
Rev0, 25-Feb-08
WLED BIAS DC/DC CONVERTER
REGISTER DESCRIPTIONS
Note: See Table 1 for default register settings.
Table 8:
REG3 Control Register Map
ADDRESS
DATA
D7
D6
D5
D4
30h
R
R
31h
R
R
R
R
32h
W/E
W/E
W/E
33h
W/E
W/E
W/E
D3
D2
D1
D0
R
R
R
W/E
W/E
W/E
W/E
W/E
W/E
R
R
W/E
OK
ON
VSET
R: Read-Only bits. Default Values May Vary.
W/E: Write-Exact bits. Read/Write bits which must be written exactly as specified in Table 1.
Table 9:
REG3 Control Register Bit Descriptions
ADDRESS
NAME
BIT
ACCESS
FUNCTION
DESCRIPTION
30h
VSET
[5:0]
R/W
REG3 Over Voltage Threshold
Selection
See Table 10
30h
[7:6]
R
READ ONLY
31h
[0]
W/E
WRITE-EXACT
31h
[7:1]
R
READ ONLY
32h
[7:0]
W/E
WRITE-EXACT
0
REG3 Disable
1
REG3 Enable
0
Output is not OK
1
Output is OK
33h
ON
[0]
R/W
REG3 Enable
33h
OK
[1]
R
REG3 Power-OK
33h
[2]
W/E
WRITE-EXACT
33h
[4:3]
R
READ ONLY
33h
[7:5]
W/E
WRITE-EXACT
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- 24 -
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Copyright © 2008 Active-Semi, Inc.
ACT8712
Rev0, 25-Feb-08
WLED BIAS DC/DC CONVERTER
REGISTER DESCRIPTIONS CONT’D
Table 10:
REG3/VSET[ ] Output Voltage Setting
REG3/VSET[4:3]
REG3/VSET
[2:0]
REG3/VSET[5] = [0]
REG3/VSET[5] = [1]
00
01
10
11
00
01
10
11
000
5.00
7.00
9.00
11.00
13.00
17.00
21.00
25.00
001
5.25
7.25
9.25
11.25
13.50
17.50
21.50
25.50
010
5.50
7.50
9.50
11.50
14.00
18.00
22.00
26.00
011
5.75
7.75
9.75
11.75
14.50
18.50
22.50
26.50
100
6.00
8.00
10.00
12.00
15.00
19.00
23.00
27.00
101
6.25
8.25
10.25
12.25
15.50
19.50
23.50
27.50
110
6.50
8.50
10.50
12.50
16.00
20.00
24.00
28.00
111
6.75
8.75
10.75
12.75
16.50
20.50
24.50
28.50
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- 25 -
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Copyright © 2008 Active-Semi, Inc.
ACT8712
Rev0, 25-Feb-08
WLED BIAS DC/DC CONVERTER
TYPICAL PERFORMANCE CHARACTERISTICS
(ACT8712QLEHA, VVSYS = 3.6V, L = 22µH, CVP1 = CVP2 = 2.2µF, COUT = 2.2µF, TA = 25°C, unless otherwise specified.)
REG3 Efficiency vs. Output Current
PWM Output Current Adjustment
Efficiency (%)
90
6 LEDs
Normalized Output Current (%)
4 LEDs
80
70
60
50
1
5
9
13
17
21
25
ON2 PWM Frequency = 1kHz
90
80
70
60
50
40
30
20
10
0
0
31
10
20
30
40
50
60
70
80
Output Current (mA)
ON2 Duty Cycle (%)
REG3 RDSON
REG3 Over-Voltage Protection
800
700
90
100
ACT8712-014
ACT8712-013
900
RDSON (mΩ)
100
ACT8712-012
ACT8712-011
100
CH1
600
500
400
CH2
300
0V
200
2.5
3.0
3.5
4.0
4.5
5.0
5.5
CH1: VOUT3, 10V/div
CH2: VFB3, 200mV/div
TIME: 2ms/div
VSYS Voltage (V)
REG3 Startup Waveform
ACT8712-015
CH1
0V
CH2
0V
CH1: VOUT3, 10V/div
CH2: VON2, 1V/div
TIME: 100µs/div
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I2CTM is a trademark of Philips Electronics.
- 26 -
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Copyright © 2008 Active-Semi, Inc.
ACT8712
Rev0, 25-Feb-08
WLED BIAS DC/DC CONVERTER
FUNCTIONAL DESCRIPTION
General Description
Power-OK Bit
REG3 is a highly efficient step-up DC/DC converter
that employs a fixed frequency, current-mode,
PWM architecture. This regulator is optimized for
white-LED bias applications consisting of up to
seven white-LEDs.
REG3 feature a variety of status bits that can be
read by the system microprocessor. If the voltage at
OV is greater than the OVP threshold, REG3/OK[ ]
will clear to 0.
Enabling and Disabling REG3
REG3 utilizes current-mode control and an internal
compensation network to optimize transient performance, ease compensation, and improve stability over a wide range of operating conditions. REG3
is a flexible regulator, and its external components
can be chosen to achieve the smallest possible
footprint or to achieve the highest possible efficiency.
Enable/disable control of REG3 is done through a
combination of the ACT8712’s system control circuitry, the ON2 pin, and the REG3/ON[ ] bit. REG3
may be enabled when at least one of the following
conditions exists:
1) A valid supply voltage is present at VIN
2) nMSTR is asserted low, or
3) ON1 is asserted high.
When any of these conditions exist, REG3 may be
enabled by either of the following conditions:
1) ON2 is asserted high, or
2) REG3/ON[ ] is set to [1].
When disabled, REG3's quiescent supply current
drops to just 1µA.
As with all non-synchronous step-up DC/DC converters, REG3's application circuit produces a DC
current path between the input and the output in
shutdown mode. Although the forward drop of the
WLEDs makes this leakage current very small in
most applications, it is important to consider the
effect that this may have in your application particularly when using fewer than three WLEDs.
Over-Voltage Protection
REG3 features internal over-voltage protection
(OVP) circuitry which protects the system from LED
open-circuit fault conditions. If the voltage at OV
ever reaches the over-voltage threshold, REG3 will
regulate the top of the LED strong to the OVP
threshold voltage. By default, the ACT8712's OVP
threshold is set at 28.5V, although it may be programmed to a lower value by writing to the
REG3/VSET[ ] register.
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I2CTM is a trademark of Philips Electronics.
Compensation and Stability
Inductor Selection
REG3 was designed to provide excellent performance across a wide range of applications, but was
optimized for operation with inductors in the 10µH
to 22µH range, although larger inductor values of
up to 68µH can be used to achieve the highest possible efficiency.
Optimizing for Smallest Footprint
REG3 is capable of operating with very low inductor
values in order to achieve the smallest possible
footprint. When solution size is of primary concern,
best results are achieved when using an inductor
that ensures discontinuous conduction mode (DCM)
operation over the full load current range.
Optimizing for Highest Efficiency
REG3 achieves excellent efficiency in applications
that demand the longest possible battery life. When
efficiency is the primary design consideration, best
results are achieved when using an inductor that
results in continuous conduction mode (CCM) operation and achieves very small inductor ripple current.
Output Capacitor Selection
REG3 was designed to operate with output capacitors ranging from 0.47µF to 10µF, providing design
flexibility. A 1µF output capacitor is suitable for most
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Copyright © 2008 Active-Semi, Inc.
ACT8712
Rev0, 25-Feb-08
WLED BIAS DC/DC CONVERTER
applications, although larger output capacitors may
be used to minimize output voltage ripple, if
needed. Ceramic capacitors are recommended for
most applications.
Rectifier Selection
REG3 requires a Schottky diode to rectify the inductor current. Select a low forward voltage drop
Schottky diode with a forward current (IF) rating that
is sufficient to support the maximum switch current
and a sufficient peak repetitive reverse voltage
(VRRM) to support the output voltage.
put filter capacitor should be connected as close
together as possible, with short, direct, and wide
traces. Connect the ground nodes together in a star
configuration, with a direct connection to the exposed pad. Finally, the exposed pad should be directly connected to the backside ground plane using multiple vias to achieve low electrical and thermal resistance. Note that since the LED string is a
low, DC-current path, it does not generally require
special layout consideration.
Setting the LED Bias Current
The LED bias current is set by a resistor connected
from FB3 and ground, and the regulator is satisfied
when the LED current is sufficient to generate
250mV across this resistor. Once the bias current is
programmed, the LED current can be adjusted using the ACT8712’s Direct-PWM feature. REG3 is
also compatible with a variety of well-known LED
dimming circuits, such as with a DC control voltage
and a filtered PWM signal.
PCB Layout Considerations
High switching frequencies and large peak currents
make PC board layout a very important part of the
design. Good design minimizes excessive EMI on
the feedback paths and voltage gradients in the
ground plane, both of which can result in instability
or regulation errors. Step-up DC/DCs exhibit continuous input current, so there is some amount of
flexibility in placing vias in the input capacitor circuit.
The inductor, input filter capacitor, rectifier, and out-
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- 28 -
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Copyright © 2008 Active-Semi, Inc.
ACT8712
Rev0, 25-Feb-08
SINGLE-CELL Li+ BATTERY CHARGER (CHGR)
ELECTRICAL CHARACTERISTICS
(VVIN = 5V, VBAT = 3.6V, ISET[ ] = [0101], TA = 25°C, unless otherwise specified.)
PARAMETER
TEST CONDITIONS
VIN Operating Voltage Range
MIN
TYP
4.3
VIN UVLO Threshold
VVIN Voltage Rising
VIN UVLO Hysteresis
VVIN Voltage Falling
3.75
V
4.25
V
mV
300
500
TA = 25°C
4.179
4.200
4.221
VVIN = 4.5V to 5.5V, TA = 0°C to 85°C
4.158
4.200
4.242
Line Regulation
VVIN = 4.5V to 5.5V, IBAT = 10mA
Load Regulation
IBAT = 50mA to 500mA
VBAT = 4V, CHGLEV = GA
Charge Current
6
500
On-Resistance
Battery Termination Voltage
4
MAX UNIT
mΩ
V
0.2
%/V
0.001
%/mA
90
100
mA
VBAT = 4V, CHGLEV = VSYS
400
450
500
mA
Precondition Charge Current
VBAT = 2.7V, CHGLEV = VSYS or GA
30
45
60
mA
Precondition Threshold Voltage
VBAT Voltage Rising
2.75
2.9
3.05
V
Precondition Threshold Hysteresis
VBAT Voltage Falling
End-of-Charge Current Threshold
VBAT = 4.2V, CHGLEV = VSYS
150
31
End-of-Charge Delay
Charge Restart Threshold
VSET[ ] -VBAT, VBAT falling
Thermal Regulation Threshold
BAT Reverse Leakage Current
47
200
mV
110
°C
VVIN < UVLO Voltage
50
SLEEP, SUSPEND, or TIMER-FAULT state
200
PRECONDITION, FAST-CHARGE, or TOPOFF state
700
Precondition Timeout Period
TIMOSET[ ] = [01]
90
nSTAT Sink current
VnSTAT = 2V
nSTAT Output Low Voltage
nSTAT Leakage Current
CHGLEV Logic Low Input Voltage
µA
µA
min
mA
InSTAT = 1mA
0.4
V
VnSTAT = 6V
1
µA
0.4
V
2
µA
ICHGLEV ≤ -15µA
CHGLEV Tri-state Current Threshold
-2
ICHGLEV ≥ 15µA
1.4
8
2
12
c
CHGLEV Logic High Input Voltage
mA
min
0.4
4
63
4
VBAT = 4.2V, VIN = GA or BAT
VIN Supply Current
mV
V
c: Charger is suspended when CHGLEV pin current is within this range
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I2CTM is a trademark of Philips Electronics.
- 29 -
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Copyright © 2008 Active-Semi, Inc.
ACT8712
Rev0, 25-Feb-08
SINGLE-CELL Li+ BATTERY CHARGER (CHGR)
REGISTER DESCRIPTIONS
Note: See Table 1 for default register settings.
Table 11:
Battery Charger (CHGR) Control Register Map
ADDRESS
DATA
D7
D6
08h
D4
D3
D2
D1
D0
R
R
R
R
TIMOFLT
TEMPFLT
CHGRSTAT
VINPOK
R
R
R
R
W/E
ICHGSET
CHGROK
SUSCHG
ISET1
09h
TIMOSET
R
0Ah
0Bh
D5
BATFLT
ISET2
R
R
R
R
R: Read-Only bits. Default Values May Vary.
W/E: Write-Exact bits. Read/Write bits which must be written exactly as specified in Table 1.
Table 12:
Battery Charger (CHGR) Control Register Bit Descriptions
ADDRESS
NAME
08h
BIT
ACCESS
[3:0]
R
FUNCTION
READ ONLY
08h
ISET1
[7:4]
R/W
ISET1 Charger Current Selection
09h
VINPOK
[0]
R
Input Supply Power-OK
09h
CHGRSTAT
[1]
R
Charging Status
09h
TEMPFLT
[2]
R
Temperature Status
09h
TIMOFLT
[3]
R
Timeout Fault
09h
BATFLT
[4]
R
Battery Removed Fault
[5]
R
09h
09h
TIMOSET
0Ah
0Ah
ISET2
[7:6]
R/W
[3:0]
R
[7:4]
R/W
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I2CTM is a trademark of Philips Electronics.
DESCRIPTION
See Tables 13 and 14
0
Input Power is not OK
1
Input Power is OK
0
Not Charging
1
Charging
0
Temperature Fault
1
No Timeout Fault
0
No Timeout Fault
1
Timeout Fault
0
Battery Not Removed
1
Battery Removed
READ ONLY
Charge Timeout Select
00
60mins
01
90mins
10
120mins
11
No Timeout
READ ONLY
ISET2 Charger Current Selection
- 30 -
See Tables 13 and 14
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Copyright © 2008 Active-Semi, Inc.
ACT8712
Rev0, 25-Feb-08
SINGLE-CELL Li+ BATTERY CHARGER (CHGR)
REGISTER DESCRIPTIONS CONT’D
Table 12:
Battery Charger (CHGR) Control Register Bit Descriptions (Cont’d)
ADDRESS
NAME
BIT
ACCESS
FUNCTION
DESCRIPTION
0Bh
SUSCHG
[0]
R/W
Suspend Charging
0Bh
CHGROK
[1]
R
Charge Status
0Bh
ICHGSET
[2]
R/W
Charge Current Selectionc
0Bh
[3]
W/E
WRITE-EXACT
0Bh
[7:4]
R
READ ONLY
0
Charging Enable
1
Charging Disable
0
Charging Error Occurred
1
Charging OK
0
90mA
1
450mA
c: ICHGSET only has affect when CHGLEV = 0 and ISET2[3:0] = [0000]
Table 13:
Table 14:
Charge Current Setting for CHGLEV = 0
Charge Current Setting for CHGLEV = 1
CHGLEV = 0
ISET1[3:0]
ISET2[3:0]
CURRENT(mA)
ISET1[3:0]
90 if ICHGSET = 0
0000
450
450 if ICHGSET = 1
0001
300
0001
300
0010
350
0010
350
0011
400
0011
400
0100
450
0100
450
0101
500
0101
500
0110
550
0110
550
0111
0111
600
1000
1000
650
1001
700
1001
700
1010
750
1010
750
1011
800
1011
800
1100
850
1100
850
1101
900
1101
900
1110
950
1110
950
1111
1000
1111
1000
0000
Any Value
CHGLEV = 1
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- 31 -
ISET2[3:0]
Any Value
CURRENT(mA)
600
650
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Copyright © 2008 Active-Semi, Inc.
ACT8712
Rev0, 25-Feb-08
SINGLE-CELL Li+ BATTERY CHARGER (CHGR)
TYPICAL PERFORMANCE CHARACTERISTICS
(ACT8712QLEHA, VVIN = 5V, TA = 25°C, unless otherwise specified.)
Trickle-Charge Threshold
Charge Termination Voltage
4.206
4.204
Trickle-Charge Threshold (V)
VBAT Voltage Accuracy (V)
4.208
4.202
4.200
4.198
4.196
4.194
4.192
4.190
0
2.9
VBAT RISING
2.8
VBAT FALLING
2.7
2.6
2.5
10
20
30
40
50
60
70
0
10
20
SUSPEND Mode Battery Current
VIN FLOATING
VVIN = 5V
1
LOGIC HIGH INPUT
3
FLOATING INPUT
0
-3
LOGIC LOW INPUT
-6
0
20
30
40
50
60
70
-20
-40
0
Temperature (°C)
MOSFET Resistance
Max. Charge Current (mA)
RDSON (mΩ)
150
100
50
0
40
50
60
ActivePMUTM is a trademark of Active-Semi.
I2CTM is a trademark of Philips Electronics.
1000
CHGLEV = VSYS
800
CHARGE CURRENT LIMITED BY
THERMAL CONTROL CIRCUITRY
600
400
CHGLEV = GA
200
0
-40
70
Temperature (°C)
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85
ACT8712-021
200
30
60
1100
ACT8712-020
250
20
40
Maximum Charge Current
300
10
20
Temperature (°C)
350
0
70
CHGLEV Drive Current Threshold
CHGLEV Drive Current (µA)
BAT Current (µA)
VIN = GA
10
60
ACT8712-019
4
0
50
6
ACT8712-018
5
2
40
30
Temperature (°C)
Temperature (°C)
3
ACT8712-017
3.0
ACT8712-016
4.210
-25
5
35
65
95
125
Temperature (°C)
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Copyright © 2008 Active-Semi, Inc.
ACT8712
Rev0, 25-Feb-08
SINGLE-CELL Li+ BATTERY CHARGER (CHGR)
FUNCTIONAL DESCRIPTION
General Description
Charger Status
The ACT8712's internal battery charger is a fullfeatured, intelligent, linear-mode, single-cell charger
for Lithium-based cells. This charger provides a
complete selection of advanced functions and requires minimum system design effort.
During normal operation, the processor can read
the status of the input supply by reading
CHGR/VINPOK[ ], which is set to [1] when the following conditions are true:
The core of the charger is a CC/CV (Constant- Current/Constant-Voltage), linear-mode charge controller with a highly-accurate charge termination threshold. This controller incorporates current and voltage
sense circuitry, an internal power MOSFET, a fullfeatured state-machine that implements charge
control and safety features, and circuitry that eliminates the reverse-blocking diode required by conventional charger designs. The ACT8712’s charger
also features thermal-regulation circuitry that protects it against excessive junction temperature, allowing the fastest possible charging times, as well
as proprietary input protection circuitry that makes
the charger robust against input voltage transients
that can damage other chargers.
CC/CV Regulation Loop
At the core of the ACT8712's battery charger is a
CC/CV regulation loop, which regulates either current or voltage as necessary to ensure fast and safe
charging of the battery. In a normal charge cycle,
this loop regulates the charge current to the programmed charge current level and continues charging at this current until the battery cell voltage
reaches the charge termination voltage. Once the
cell reaches the Charge-Termination Threshold
Voltage, the CV loop takes over and charge current
is allowed to decrease as necessary to keep the
cell voltage at the charge termination voltage.
Charger Enable/Disable
1) The voltage at VIN is greater than the voltage at
BAT, and
2) The voltage at VIN is greater than the VIN
UVLO threshold.
Alternatively, the processor can read the status of
the charger by reading the CHGR/CHGROK[ ] bit,
which is set to [1] when the following conditions are
true:
1) The voltage at VIN is greater than the voltage at
BAT, and
2) The voltage at VIN is greater than the VIN
UVLO threshold, and
3) No fault has occurred.
Finally, the status of a charge cycle can be determine by reading the CHGR/CHGSTAT[ ] bit or by
evaluating the state of the nSTAT output. nSTAT is
an open-drain output that has an internal 8mA current limit, and is capable of directly driving LEDs for
a visual charge-status indication without the need of
current-limiting resistors or other external circuitry.
To drive an LED, simply connect the LED between
an appropriate supply, typically VIN, and nSTAT.
When a logic-level charge status indicator is desired, simply connect a pull-up resistor of 10kΩ or
more from nSTAT to OUT2 or another suitable supply.
CHGR/CHGSTAT[ ] is set to [1] and nSTAT sinks
current when any of the following conditions are
true:
When a valid input voltage is applied to VIN, the
battery charger is automatically enabled in order to
simplify system design and eliminate the need for
external input supply detection circuitry.
1) The charger is operating in the PRECONDITION state, or
Once the charger is enabled, a charge cycle automatically begins unless CHGLEV is floating,
CHGR/SUSCHG[ ] is set to [1], or a fault condition
has occurred.
3) The charger is operating in the TOP-OFF state.
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2) The charger is operating in the FAST-CHARGE
state, or
When none of these conditions are true,
CHGR/CHGSTAT[ ] is cleared to [0] and nSTAT
goes into a high-Z state.
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ACT8712
Rev0, 25-Feb-08
SINGLE-CELL Li+ BATTERY CHARGER (CHGR)
Input Capacitor Selection
VIN is the power input pin for the ACT8712 battery
charger. The battery charger is automatically enabled whenever a valid voltage is present on VIN.
In most applications, VIN is connected to either a
wall adapter or a USB port. Under normal operation, the input of the charger will often be “hotplugged” directly to a powered USB or a wall
adapter cable, and supply voltage ringing and overshoot may appear at the VIN pin and can potentially
be large enough to damage the charger input. In
most applications, a capacitor connected from VIN
to GA, placed as close as possible to the IC, is sufficient to absorb the energy. The VIN pin is designed for enhanced robustness and has an absolute maximum transient voltage rating of +7V, and
attention must be given to bypass techniques to
ensure operation within this limit.
Charge Current Programming
Charge current programming is performed using a
combination of the ACT8712’s CHGR/ISET1[ ] and
CHGR/ISET2[e] registers and the multifunction
CHGLEV input. The multi-function CHGLEV input
provides charge-current selection between the current setting defined by CHGR/ISET1[ ] and the current setting programmed by CHGR/ISET2[ ], as well
as a charge suspend function. Drive CHGLEV to a
logic-low to select the current programmed by
CHGR/ISET1[ ]. In order to reduce the number of
GPIOs required to interface with the ACT8712, the
CHGR/ICHGSET[ ] bit may be used instead of the
CHGLEV pin to achieve identical functionality.
By default, the ACT8712’s CHGR/ISET1[ ] and
CHGR/ISET2[ ] registers are programmed to provide a charge current of 90mA when CHGLEV is
driven low, and 450mA when CHGLEV is driven
high, so that the ACT8712 is compatible with system that utilize lower-current input supplies, such as
a USB port. To achieve a different charge current,
program the CHGR/ISET1[ ] and/or CHGR/ISET2[ ]
registers accordingly.
Charge Safety Timer
The ACT8712 features a programmable charge
safety timer that is utilized during operation in the
PRECONDITION state. The safety timer has a default timeout period of 60 minutes, although it may
be programmed to either 90 minutes or 120 minutes
by writing to the CHGR/TIMOSET[ ] register. This
register also provides a timer-disable function, for
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I2CTM is a trademark of Philips Electronics.
applications that do not require a charge safety
timer function.
Thermal Regulation
The ACT8712 features an internal thermal feedback
loop that reduces the charging current as necessary
to ensure that the die temperature does not exceed
the thermal regulation threshold of 110°C. This feature protects the ACT8712 against excessive junction temperature and makes the ACT8712 more
accommodating of aggressive thermal designs without risk of damage. Note, however, that attention to
good thermal design is required to achieve the
shortest possible charge time.
Charge Status Bits
The ACT8712 charger provides a variety of readonly charge status bits that can be read by the host
processor as needed to make intelligent power
management decisions. Five charge status bits are
available:
Input Voltage Status
The CHGR/VINPOK[ ] bit is set to [1] when a valid
input supply is connected to VIN. A valid input supply is defined as one that :
1) is greater than the voltage at BAT, and
2) is greater than the VIN UVLO threshold.
Charger Status
There are two bits available that describe the current status of the charger itself.
The CHGR/CHGSTAT[ ] bit is set to [1] when the
charger is actively charging the battery, and is
cleared to [0] when a charge cycle terminates or is
suspended.
The CHGR/CHGROK[ ] bit is set to [1] when TBD,
and is cleared otherwise.
Timeout Fault
The CHGR/TIMOFLT[ ] bit is set to [1] when a timeout fault occurs, and remains cleared otherwise.
Once set to [1], it is automatically cleared to [0]
when TBD.
Battery Removed Fault
The CHGR/BATFLT[ ] bit is set to [1] when there is
no battery connected, and remains cleared otherwise.
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ACT8712
Rev0, 25-Feb-08
SINGLE-CELL Li+ BATTERY CHARGER (CHGR)
SLEEP State
Reverse Leakage Current
The ACT8712 includes internal circuitry that eliminates the need for series blocking diodes, reducing
solution size and cost as well as dropout voltage
relative to conventional battery chargers. When the
input supply is removed, when VVIN goes below its
under-voltage-lockout (UVLO) voltage, or when VVIN
drops below VBAT, the ACT8712 automatically goes
into SUSPEND mode and reconfigures its power
switch to minimize current drain from the battery.
Charger State Machine
PRECONDITION State
A new charging cycle begins in the PRECONDITION state. In this state, the cell is charged at a
reduced current of either 45mA or 10% of the selected maximum fast-charge current, whichever is
greater. During a normal charge cycle, charging
continues at this rate until VBAT reaches the Precondition Threshold Voltage, at which point the state
machine jumps to the FAST-CHARGE state. If VBAT
does not reach the Precondition Threshold Voltage
before the Precondition Charge Timeout period expires, then a damaged cell is detected and the state
machine jumps to the TIMEOUT-FAULT state.
FAST-CHARGE State
In the FAST-CHARGE state the charger operates in
Constant-Current (CC) mode and charges the cell
at the programmed charge current. During a normal
charge cycle, constant-current charging continues
until VBAT reaches the charge termination voltage, at
which point the state machine jumps to the TOPOFF state.
TOP-OFF State
In the TOP-OFF state the cell is charged in Constant-Voltage (CV) mode with the charge current
limited by the internal chemistry of the cell, decreasing as the cell charges. A normal charging cycle
continues until the charge current decreases to below the End-Of-Charge (EOC) threshold. In order to
improve immunity to conditions that can result in
false-EOC detection, the charging continues until
the EOC condition persists for 4 consecutive minutes. Once this condition is met, the charge cycle is
terminated and the state machine jumps to the
SLEEP state.
Innovative Products. Active Solutions.
ActivePMUTM is a trademark of Active-Semi.
I2CTM is a trademark of Philips Electronics.
In the SLEEP state the ACT8712 presents a highimpedance to the battery, allowing the cell to “relax”
and minimizing battery leakage current. The
ACT8712 continues to monitor the cell voltage,
however, so that it can reinitiate a charging cycle as
necessary to ensure that the cell remains fully
charged.
Charge Restart
After a charge cycle successfully terminates, the
ACT8712 jumps to its SLEEP state to minimize battery drain, but continues to actively monitor the cell
voltage. A new charging cycle begins when the cell
voltage has dropped by 200mV (typ), keeping the
cell fully charged. This charge restart process minimizes cycle-life degradation of the cell by allowing it
to “relax” between charges, while ensuring that the
cell remains fully-charged while connected to a
power source.
SUSPEND State
When in the SUSPEND state, the charger is disabled and the charger presents a high-impedance
to the battery, but the charge-control circuitry remains functional. When exiting the SUSPEND
state, the charge timer is reset and the state machine jumps to the PRECONDITION state.
TIMEOUT-FAULT State
When a TIMEOUT-FAULT occurs, charging is suspended, CHGR/TIMOFLT[ ] is set to [1], and the
charger presents a high-impedance to the battery.
To maximize safety, there is no direct path to resume charging from the TIMEOUT-FAULT state. A
new charging cycle may only be initiated if the state
machine first jumps to the SUSPEND state then
each of the conditions necessary to enter the PRECONDITION state are satisfied.
- 35 -
www.active-semi.com
Copyright © 2008 Active-Semi, Inc.
ACT8712
Rev0, 25-Feb-08
PACKAGE INFORMATION
PACKAGE OUTLINE
TQFN44-24 PACKAGE OUTLINE AND DIMENSIONS
D
D/2
SYMBOL
E/2
E
PIN #1 INDEX AREA
DIMENSION IN
MILLIMETERS
DIMENSION IN
INCHES
MIN
MAX
MIN
MAX
A
0.700
0.800
0.028
0.031
A1
0.000
0.050
0.000
0.002
A3
0.200 REF
0.008 REF
D/2 x E/2
A
A3
A1
0.180
0.300
0.007
0.012
D
3.850
4.150
0.152
0.163
E
3.850
4.150
0.152
0.163
D2
2.500
2.800
0.098
0.110
E2
2.500
2.800
0.098
0.110
e
D2
L
b
b
L
R
e
K
0.500 BSC
0.350
0.450
0.200 TYP
0.200
---
0.020 BSC
0.014
0.018
0.008 TYP
0.008
---
E2
PIN #1 INDEX AREA
D/2 x E/2
K
R
Active-Semi, Inc. reserves the right to modify the circuitry or specifications without notice. Users should evaluate each product to make
sure that it is suitable for their applications. Active-Semi products are not intended or authorized for use as critical components in lifesupport devices or systems. Active-Semi, Inc. does not assume any liability arising out of the use of any product or circuit described in
this datasheet, nor does it convey any patent license.
Active-Semi and its logo are trademarks of Active-Semi, Inc. For more information on this and other products, contact [email protected] or visit http://www.active-semi.com. For other inquiries, please send to:
1270 Oakmead Parkway, Suite 310, Sunnyvale, California 94085-4044, USA
Innovative Products. Active Solutions.
ActivePMUTM is a trademark of Active-Semi.
I2CTM is a trademark of Philips Electronics.
- 36 -
www.active-semi.com
Copyright © 2008 Active-Semi, Inc.