Fairchild FAN5631, FAN5632 service manual

October 2007

FAN5631 / FAN5632 Regulated Step-Down Charge Pump DC/DC Converter

FAN5631 / FAN5632 — Regulated Step Down Charge Pump DC/DC Converter

Features

 90% Peak Efficiency  Low EMI  Low Ripple  Selectable Output Voltage:1.2V/1.5V for FAN5631  Efficiency Optimizer Feature for FAN5632  Input Voltage Range: 2.2V to 5.5V  Output Current: Up to 250mA  ±5% Output Voltage Accuracy  30µA Operating Current  I

<1mA in Shutdown Mode

 1.5MHz Operating Frequency  Shutdown Isolates Output from Input  Soft-Start Limits Inrush Current  Short-Circuit and Over-Temperature Protection  Minimum External Component Count  10-Lead 3x3mm MLP Package

Applications

 Cell Phones  Handheld Computers  Portable Electronic Equipment  Core Supply to Next-Generation Processors  Low-Voltage DC Bus  Digital Cameras  DSP Supplies

Description

The FAN5631/FAN5632 is an advanced, thirdgeneration switched capacitor step-down DC/DC converter utilizing Fairchild's proprietary ScalarPump technology. This innovative architecture utilizes scalar switch re-configuration and fractional switching techniques to produce low output ripple, lower ESR spikes, and improve efficiency over a wide load range.

The FAN5631/FAN5632 produces a fixed regulated output voltage from an input voltage of 2.2V to 5V.

To maximize efficiency, the FAN5631/5632 achieves regulation by skipping pulses. Depending on load current, the size of the switches are scaled dynamically; consequently, current spikes and EMI are minimized. An internal soft-start circuitry prevents excessive current from the supply. The device is internally protected against short-circuit and over-temperature conditions.

The FAN5631 has a dual-output voltage feature. When V

is high, V

SEL

1.2V. The FAN5632 has an efficiency optimizer feature that,

when enabled, changes the switch mode configuration from 2:1 to 1:1 at the lower threshold of V efficiency is maintained at its peak level over a wider range of input voltages. In addition, V

1.2V to 1.5V as a result of this efficiency optimization. If the efficiency optimizer is not enabled, V to 1.5V.

Both the FAN5631 and FAN5632 are available in a 10lead 3x3mm MLP package.

is 1.5V; and when V

OUT

is low, V

SEL

varies from

OUT

is regulated

OUT

. The

Ordering Information

Part Number Package Packing Method

FAN5631MPX 10-Lead 3x3mm Molded Leadless Package (MLP) Tape and Reel FAN5632MPX 10-Lead 3x3mm Molded Leadless Package (MLP) Tape and Reel

All packages are lead free per JEDEC: J-STD-020B standard.

Typical Application

FAN5631 / FAN5632 — Regulated Step Down Charge Pump DC/DC Converter

SEL

9 8

OUT

10µF

OUT

OUT_max

= 2.7V to 5.5V

= 1.2V to 1.5V

= 250mA

OFF

GND

2 3

4 5

10µF

Figure 1. Typical Application

FAN5631 FAN5632 with optimization

Average Efficiency (over VIN=2.7V to 5V) = 66%, with optimization = 77% Average Efficiency (over V

=2.7V to 4.2V) = 67%, with optimization = 84%

Figure 2. Typical Efficiency Graph

Pin Configuration

FAN5631 / FAN5632 — Regulated Step Down Charge Pump DC/DC Converter

Top View

Pin Definitions

Pin # Name Description

Output Voltage Select Logic Input Pin. The V

connected to either a logic high or logic low level. FAN5631: If a logic low is applied to the V

1 V

2 EN

3 CB+ 4 GND 5 CB-

6 V 7 NC 8 NC 9 VIN

10 NC

SEL

OUT

applied, V FAN5632: If a logic low is applied to the V

and the output voltage accuracy is relaxed to meet optimum efficiency. If a logic high is applied, the device operates like a typical charge pump converter.

Enable Input Pin. If a logic high is applied to the EN pin, the device is enabled. If a logic low is applied, the device is disabled and the supply current is reduced to less than 1µA. The EN pin cannot be left floating and must be connected to a logic high or logic low level.

Bucket Capacitor Positive Pin. Ground Pin. This pin is connected to the internal MOSFET switches. This pin must be

externally connected to GND.

Bucket Capacitor Negative Pin. Output Voltage Pin. Not Connected. This pin is not internally connected. Not Connected. This pin is not internally connected. Supply Voltage Input. Not Connected. This pin is not internally connected.

OUT

SEL

GND

is 1.5V.

1 2 3 4 5

Figure 3. Pin Assignments

9 8 7 6

SEL

pin, V

SEL

pin, the efficiency optimization mode is enabled

SEL

NC V

NC NC V

pin cannot be left floating and must be

is 1.2V; if a logic high is

OUT

FAN5631 / FAN5632 — Regulated Step Down Charge Pump DC/DC Converter

Absolute Maximum Ratings

Stresses exceeding the absolute maximum ratings may damage the device. The device may not function or be operable above the recommended operating conditions and stressing the parts to these levels is not recommended. In addition, extended exposure to stresses above the recommended operating conditions may affect device reliability. The absolute maximum ratings are stress ratings only.

Symbol Parameter Min. Max. Unit

VCC

LOAD

TL Lead Temperature, Soldering 10 Seconds +260 °C TJ Junction Temperature -40 +150 °C

STG

(2)

ESD

Notes:

1. Junction-to-ambient thermal resistance, number of copper planes, number of via used, diameter of via used, available copper surface, and attached heat sink characteristics. The estimated value for zero air flow at 0.5W is 60°C/W.

2. Using Mil Std. 883E, method 3015.7 (Human Body Model) and EIA/JESD22C101-A (Charged Device Model).

VIN to GND -0.3 6.0 All other pins to GND -0.3 V

+ 0.3

Load Current 0.5 A

Thermal Resistance Junction-to-Tab

(1)

°C/W

Storage Temperature -65 +150 °C

Human Body Model, JESD22-A114 2.5 Charged Device Model, JESD22-C101 0.2

, is a strong function of PCB material, board thickness, thickness and

Recommended Operating Conditions

The Recommended Operating Conditions table defines the conditions for actual device operation. Recommended operating conditions are specified to ensure optimal performance to the datasheet specifications. Fairchild does not recommend exceeding them or designing to Absolute Maximum Ratings.

Symbol Parameter Min. Typ. Max. Unit

VCC Supply Voltage Range 2.2 5.5 V I

Output Current (VIN > 2.V) 250 mA

OUT

TA Operating Ambient Temperature Range -40 +25 +85 °C

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